okay fine

.venv/lib/python3.12/site-packages/automat/__init__.py

@@ -0,0 +1,16 @@
+# -*- test-case-name: automat -*-
+"""
+State-machines.
+"""
+from ._typed import TypeMachineBuilder, pep614, AlreadyBuiltError, TypeMachine
+from ._core import NoTransition
+from ._methodical import MethodicalMachine
+
+__all__ = [
+    "TypeMachineBuilder",
+    "TypeMachine",
+    "NoTransition",
+    "AlreadyBuiltError",
+    "pep614",
+    "MethodicalMachine",
+]

.venv/lib/python3.12/site-packages/automat/_core.py

@@ -0,0 +1,203 @@
+# -*- test-case-name: automat._test.test_core -*-
+
+"""
+A core state-machine abstraction.
+
+Perhaps something that could be replaced with or integrated into machinist.
+"""
+from __future__ import annotations
+
+import sys
+from itertools import chain
+from typing import Callable, Generic, Optional, Sequence, TypeVar, Hashable
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+_NO_STATE = "<no state>"
+State = TypeVar("State", bound=Hashable)
+Input = TypeVar("Input", bound=Hashable)
+Output = TypeVar("Output", bound=Hashable)
+
+
+class NoTransition(Exception, Generic[State, Input]):
+    """
+    A finite state machine in C{state} has no transition for C{symbol}.
+
+    @ivar state: See C{state} init parameter.
+
+    @ivar symbol: See C{symbol} init parameter.
+    """
+
+    def __init__(self, state: State, symbol: Input):
+        """
+        Construct a L{NoTransition}.
+
+        @param state: the finite state machine's state at the time of the
+            illegal transition.
+
+        @param symbol: the input symbol for which no transition exists.
+        """
+        self.state = state
+        self.symbol = symbol
+        super(Exception, self).__init__(
+            "no transition for {} in {}".format(symbol, state)
+        )
+
+
+class Automaton(Generic[State, Input, Output]):
+    """
+    A declaration of a finite state machine.
+
+    Note that this is not the machine itself; it is immutable.
+    """
+
+    def __init__(self, initial: State | None = None) -> None:
+        """
+        Initialize the set of transitions and the initial state.
+        """
+        if initial is None:
+            initial = _NO_STATE  # type:ignore[assignment]
+        assert initial is not None
+        self._initialState: State = initial
+        self._transitions: set[tuple[State, Input, State, Sequence[Output]]] = set()
+        self._unhandledTransition: Optional[tuple[State, Sequence[Output]]] = None
+
+    @property
+    def initialState(self) -> State:
+        """
+        Return this automaton's initial state.
+        """
+        return self._initialState
+
+    @initialState.setter
+    def initialState(self, state: State) -> None:
+        """
+        Set this automaton's initial state.  Raises a ValueError if
+        this automaton already has an initial state.
+        """
+
+        if self._initialState is not _NO_STATE:
+            raise ValueError(
+                "initial state already set to {}".format(self._initialState)
+            )
+
+        self._initialState = state
+
+    def addTransition(
+        self,
+        inState: State,
+        inputSymbol: Input,
+        outState: State,
+        outputSymbols: tuple[Output, ...],
+    ):
+        """
+        Add the given transition to the outputSymbol. Raise ValueError if
+        there is already a transition with the same inState and inputSymbol.
+        """
+        # keeping self._transitions in a flat list makes addTransition
+        # O(n^2), but state machines don't tend to have hundreds of
+        # transitions.
+        for anInState, anInputSymbol, anOutState, _ in self._transitions:
+            if anInState == inState and anInputSymbol == inputSymbol:
+                raise ValueError(
+                    "already have transition from {} to {} via {}".format(
+                        inState, anOutState, inputSymbol
+                    )
+                )
+        self._transitions.add((inState, inputSymbol, outState, tuple(outputSymbols)))
+
+    def unhandledTransition(
+        self, outState: State, outputSymbols: Sequence[Output]
+    ) -> None:
+        """
+        All unhandled transitions will be handled by transitioning to the given
+        error state and error-handling output symbols.
+        """
+        self._unhandledTransition = (outState, tuple(outputSymbols))
+
+    def allTransitions(self) -> frozenset[tuple[State, Input, State, Sequence[Output]]]:
+        """
+        All transitions.
+        """
+        return frozenset(self._transitions)
+
+    def inputAlphabet(self) -> set[Input]:
+        """
+        The full set of symbols acceptable to this automaton.
+        """
+        return {
+            inputSymbol
+            for (inState, inputSymbol, outState, outputSymbol) in self._transitions
+        }
+
+    def outputAlphabet(self) -> set[Output]:
+        """
+        The full set of symbols which can be produced by this automaton.
+        """
+        return set(
+            chain.from_iterable(
+                outputSymbols
+                for (inState, inputSymbol, outState, outputSymbols) in self._transitions
+            )
+        )
+
+    def states(self) -> frozenset[State]:
+        """
+        All valid states; "Q" in the mathematical description of a state
+        machine.
+        """
+        return frozenset(
+            chain.from_iterable(
+                (inState, outState)
+                for (inState, inputSymbol, outState, outputSymbol) in self._transitions
+            )
+        )
+
+    def outputForInput(
+        self, inState: State, inputSymbol: Input
+    ) -> tuple[State, Sequence[Output]]:
+        """
+        A 2-tuple of (outState, outputSymbols) for inputSymbol.
+        """
+        for anInState, anInputSymbol, outState, outputSymbols in self._transitions:
+            if (inState, inputSymbol) == (anInState, anInputSymbol):
+                return (outState, list(outputSymbols))
+        if self._unhandledTransition is None:
+            raise NoTransition(state=inState, symbol=inputSymbol)
+        return self._unhandledTransition
+
+
+OutputTracer = Callable[[Output], None]
+Tracer: TypeAlias = "Callable[[State, Input, State], OutputTracer[Output] | None]"
+
+
+class Transitioner(Generic[State, Input, Output]):
+    """
+    The combination of a current state and an L{Automaton}.
+    """
+
+    def __init__(self, automaton: Automaton[State, Input, Output], initialState: State):
+        self._automaton: Automaton[State, Input, Output] = automaton
+        self._state: State = initialState
+        self._tracer: Tracer[State, Input, Output] | None = None
+
+    def setTrace(self, tracer: Tracer[State, Input, Output] | None) -> None:
+        self._tracer = tracer
+
+    def transition(
+        self, inputSymbol: Input
+    ) -> tuple[Sequence[Output], OutputTracer[Output] | None]:
+        """
+        Transition between states, returning any outputs.
+        """
+        outState, outputSymbols = self._automaton.outputForInput(
+            self._state, inputSymbol
+        )
+        outTracer = None
+        if self._tracer:
+            outTracer = self._tracer(self._state, inputSymbol, outState)
+        self._state = outState
+        return (outputSymbols, outTracer)

.venv/lib/python3.12/site-packages/automat/_discover.py

@@ -0,0 +1,168 @@
+from __future__ import annotations
+
+import collections
+import inspect
+from typing import Any, Iterator
+
+from twisted.python.modules import PythonAttribute, PythonModule, getModule
+
+from automat import MethodicalMachine
+
+from ._typed import TypeMachine, InputProtocol, Core
+
+
+def isOriginalLocation(attr: PythonAttribute | PythonModule) -> bool:
+    """
+    Attempt to discover if this appearance of a PythonAttribute
+    representing a class refers to the module where that class was
+    defined.
+    """
+    sourceModule = inspect.getmodule(attr.load())
+    if sourceModule is None:
+        return False
+
+    currentModule = attr
+    while not isinstance(currentModule, PythonModule):
+        currentModule = currentModule.onObject
+
+    return currentModule.name == sourceModule.__name__
+
+
+def findMachinesViaWrapper(
+    within: PythonModule | PythonAttribute,
+) -> Iterator[tuple[str, MethodicalMachine | TypeMachine[InputProtocol, Core]]]:
+    """
+    Recursively yield L{MethodicalMachine}s and their FQPNs within a
+    L{PythonModule} or a L{twisted.python.modules.PythonAttribute}
+    wrapper object.
+
+    Note that L{PythonModule}s may refer to packages, as well.
+
+    The discovery heuristic considers L{MethodicalMachine} instances
+    that are module-level attributes or class-level attributes
+    accessible from module scope.  Machines inside nested classes will
+    be discovered, but those returned from functions or methods will not be.
+
+    @type within: L{PythonModule} or L{twisted.python.modules.PythonAttribute}
+    @param within: Where to start the search.
+
+    @return: a generator which yields FQPN, L{MethodicalMachine} pairs.
+    """
+    queue = collections.deque([within])
+    visited: set[
+        PythonModule
+        | PythonAttribute
+        | MethodicalMachine
+        | TypeMachine[InputProtocol, Core]
+        | type[Any]
+    ] = set()
+
+    while queue:
+        attr = queue.pop()
+        value = attr.load()
+        if (
+            isinstance(value, MethodicalMachine) or isinstance(value, TypeMachine)
+        ) and value not in visited:
+            visited.add(value)
+            yield attr.name, value
+        elif (
+            inspect.isclass(value) and isOriginalLocation(attr) and value not in visited
+        ):
+            visited.add(value)
+            queue.extendleft(attr.iterAttributes())
+        elif isinstance(attr, PythonModule) and value not in visited:
+            visited.add(value)
+            queue.extendleft(attr.iterAttributes())
+            queue.extendleft(attr.iterModules())
+
+
+class InvalidFQPN(Exception):
+    """
+    The given FQPN was not a dot-separated list of Python objects.
+    """
+
+
+class NoModule(InvalidFQPN):
+    """
+    A prefix of the FQPN was not an importable module or package.
+    """
+
+
+class NoObject(InvalidFQPN):
+    """
+    A suffix of the FQPN was not an accessible object
+    """
+
+
+def wrapFQPN(fqpn: str) -> PythonModule | PythonAttribute:
+    """
+    Given an FQPN, retrieve the object via the global Python module
+    namespace and wrap it with a L{PythonModule} or a
+    L{twisted.python.modules.PythonAttribute}.
+    """
+    # largely cribbed from t.p.reflect.namedAny
+
+    if not fqpn:
+        raise InvalidFQPN("FQPN was empty")
+
+    components = collections.deque(fqpn.split("."))
+
+    if "" in components:
+        raise InvalidFQPN(
+            "name must be a string giving a '.'-separated list of Python "
+            "identifiers, not %r" % (fqpn,)
+        )
+
+    component = components.popleft()
+    try:
+        module = getModule(component)
+    except KeyError:
+        raise NoModule(component)
+
+    # find the bottom-most module
+    while components:
+        component = components.popleft()
+        try:
+            module = module[component]
+        except KeyError:
+            components.appendleft(component)
+            break
+        else:
+            module.load()
+    else:
+        return module
+
+    # find the bottom-most attribute
+    attribute = module
+    for component in components:
+        try:
+            attribute = next(
+                child
+                for child in attribute.iterAttributes()
+                if child.name.rsplit(".", 1)[-1] == component
+            )
+        except StopIteration:
+            raise NoObject("{}.{}".format(attribute.name, component))
+
+    return attribute
+
+
+def findMachines(
+    fqpn: str,
+) -> Iterator[tuple[str, MethodicalMachine | TypeMachine[InputProtocol, Core]]]:
+    """
+    Recursively yield L{MethodicalMachine}s and their FQPNs in and under the a
+    Python object specified by an FQPN.
+
+    The discovery heuristic considers L{MethodicalMachine} instances that are
+    module-level attributes or class-level attributes accessible from module
+    scope.  Machines inside nested classes will be discovered, but those
+    returned from functions or methods will not be.
+
+    @param fqpn: a fully-qualified Python identifier (i.e. the dotted
+        identifier of an object defined at module or class scope, including the
+        package and modele names); where to start the search.
+
+    @return: a generator which yields (C{FQPN}, L{MethodicalMachine}) pairs.
+    """
+    return findMachinesViaWrapper(wrapFQPN(fqpn))

.venv/lib/python3.12/site-packages/automat/_introspection.py

@@ -0,0 +1,57 @@
+"""
+Python introspection helpers.
+"""
+
+from types import CodeType as code, FunctionType as function
+
+
+def copycode(template, changes):
+    if hasattr(code, "replace"):
+        return template.replace(**{"co_" + k: v for k, v in changes.items()})
+    names = [
+        "argcount",
+        "nlocals",
+        "stacksize",
+        "flags",
+        "code",
+        "consts",
+        "names",
+        "varnames",
+        "filename",
+        "name",
+        "firstlineno",
+        "lnotab",
+        "freevars",
+        "cellvars",
+    ]
+    if hasattr(code, "co_kwonlyargcount"):
+        names.insert(1, "kwonlyargcount")
+    if hasattr(code, "co_posonlyargcount"):
+        # PEP 570 added "positional only arguments"
+        names.insert(1, "posonlyargcount")
+    values = [changes.get(name, getattr(template, "co_" + name)) for name in names]
+    return code(*values)
+
+
+def copyfunction(template, funcchanges, codechanges):
+    names = [
+        "globals",
+        "name",
+        "defaults",
+        "closure",
+    ]
+    values = [
+        funcchanges.get(name, getattr(template, "__" + name + "__")) for name in names
+    ]
+    return function(copycode(template.__code__, codechanges), *values)
+
+
+def preserveName(f):
+    """
+    Preserve the name of the given function on the decorated function.
+    """
+
+    def decorator(decorated):
+        return copyfunction(decorated, dict(name=f.__name__), dict(name=f.__name__))
+
+    return decorator

.venv/lib/python3.12/site-packages/automat/_methodical.py

@@ -0,0 +1,545 @@
+# -*- test-case-name: automat._test.test_methodical -*-
+from __future__ import annotations
+
+import collections
+import sys
+from dataclasses import dataclass, field
+from functools import wraps
+from inspect import getfullargspec as getArgsSpec
+from itertools import count
+from typing import Any, Callable, Hashable, Iterable, TypeVar
+
+if sys.version_info < (3, 10):
+    from typing_extensions import TypeAlias
+else:
+    from typing import TypeAlias
+
+from ._core import Automaton, OutputTracer, Tracer, Transitioner
+from ._introspection import preserveName
+
+ArgSpec = collections.namedtuple(
+    "ArgSpec",
+    [
+        "args",
+        "varargs",
+        "varkw",
+        "defaults",
+        "kwonlyargs",
+        "kwonlydefaults",
+        "annotations",
+    ],
+)
+
+
+def _getArgSpec(func):
+    """
+    Normalize inspect.ArgSpec across python versions
+    and convert mutable attributes to immutable types.
+
+    :param Callable func: A function.
+    :return: The function's ArgSpec.
+    :rtype: ArgSpec
+    """
+    spec = getArgsSpec(func)
+    return ArgSpec(
+        args=tuple(spec.args),
+        varargs=spec.varargs,
+        varkw=spec.varkw,
+        defaults=spec.defaults if spec.defaults else (),
+        kwonlyargs=tuple(spec.kwonlyargs),
+        kwonlydefaults=(
+            tuple(spec.kwonlydefaults.items()) if spec.kwonlydefaults else ()
+        ),
+        annotations=tuple(spec.annotations.items()),
+    )
+
+
+def _getArgNames(spec):
+    """
+    Get the name of all arguments defined in a function signature.
+
+    The name of * and ** arguments is normalized to "*args" and "**kwargs".
+
+    :param ArgSpec spec: A function to interrogate for a signature.
+    :return: The set of all argument names in `func`s signature.
+    :rtype: Set[str]
+    """
+    return set(
+        spec.args
+        + spec.kwonlyargs
+        + (("*args",) if spec.varargs else ())
+        + (("**kwargs",) if spec.varkw else ())
+        + spec.annotations
+    )
+
+
+def _keywords_only(f):
+    """
+    Decorate a function so all its arguments must be passed by keyword.
+
+    A useful utility for decorators that take arguments so that they don't
+    accidentally get passed the thing they're decorating as their first
+    argument.
+
+    Only works for methods right now.
+    """
+
+    @wraps(f)
+    def g(self, **kw):
+        return f(self, **kw)
+
+    return g
+
+
+@dataclass(frozen=True)
+class MethodicalState(object):
+    """
+    A state for a L{MethodicalMachine}.
+    """
+
+    machine: MethodicalMachine = field(repr=False)
+    method: Callable[..., Any] = field()
+    serialized: bool = field(repr=False)
+
+    def upon(
+        self,
+        input: MethodicalInput,
+        enter: MethodicalState | None = None,
+        outputs: Iterable[MethodicalOutput] | None = None,
+        collector: Callable[[Iterable[T]], object] = list,
+    ) -> None:
+        """
+        Declare a state transition within the L{MethodicalMachine} associated
+        with this L{MethodicalState}: upon the receipt of the `input`, enter
+        the `state`, emitting each output in `outputs`.
+
+        @param input: The input triggering a state transition.
+
+        @param enter: The resulting state.
+
+        @param outputs: The outputs to be triggered as a result of the declared
+            state transition.
+
+        @param collector: The function to be used when collecting output return
+            values.
+
+        @raises TypeError: if any of the `outputs` signatures do not match the
+            `inputs` signature.
+
+        @raises ValueError: if the state transition from `self` via `input` has
+            already been defined.
+        """
+        if enter is None:
+            enter = self
+        if outputs is None:
+            outputs = []
+        inputArgs = _getArgNames(input.argSpec)
+        for output in outputs:
+            outputArgs = _getArgNames(output.argSpec)
+            if not outputArgs.issubset(inputArgs):
+                raise TypeError(
+                    "method {input} signature {inputSignature} "
+                    "does not match output {output} "
+                    "signature {outputSignature}".format(
+                        input=input.method.__name__,
+                        output=output.method.__name__,
+                        inputSignature=getArgsSpec(input.method),
+                        outputSignature=getArgsSpec(output.method),
+                    )
+                )
+        self.machine._oneTransition(self, input, enter, outputs, collector)
+
+    def _name(self) -> str:
+        return self.method.__name__
+
+
+def _transitionerFromInstance(
+    oself: object,
+    symbol: str,
+    automaton: Automaton[MethodicalState, MethodicalInput, MethodicalOutput],
+) -> Transitioner[MethodicalState, MethodicalInput, MethodicalOutput]:
+    """
+    Get a L{Transitioner}
+    """
+    transitioner = getattr(oself, symbol, None)
+    if transitioner is None:
+        transitioner = Transitioner(
+            automaton,
+            automaton.initialState,
+        )
+        setattr(oself, symbol, transitioner)
+    return transitioner
+
+
+def _empty():
+    pass
+
+
+def _docstring():
+    """docstring"""
+
+
+def assertNoCode(f: Callable[..., Any]) -> None:
+    # The function body must be empty, i.e. "pass" or "return None", which
+    # both yield the same bytecode: LOAD_CONST (None), RETURN_VALUE. We also
+    # accept functions with only a docstring, which yields slightly different
+    # bytecode, because the "None" is put in a different constant slot.
+
+    # Unfortunately, this does not catch function bodies that return a
+    # constant value, e.g. "return 1", because their code is identical to a
+    # "return None". They differ in the contents of their constant table, but
+    # checking that would require us to parse the bytecode, find the index
+    # being returned, then making sure the table has a None at that index.
+
+    if f.__code__.co_code not in (_empty.__code__.co_code, _docstring.__code__.co_code):
+        raise ValueError("function body must be empty")
+
+
+def _filterArgs(args, kwargs, inputSpec, outputSpec):
+    """
+    Filter out arguments that were passed to input that output won't accept.
+
+    :param tuple args: The *args that input received.
+    :param dict kwargs: The **kwargs that input received.
+    :param ArgSpec inputSpec: The input's arg spec.
+    :param ArgSpec outputSpec: The output's arg spec.
+    :return: The args and kwargs that output will accept.
+    :rtype: Tuple[tuple, dict]
+    """
+    named_args = tuple(zip(inputSpec.args[1:], args))
+    if outputSpec.varargs:
+        # Only return all args if the output accepts *args.
+        return_args = args
+    else:
+        # Filter out arguments that don't appear
+        # in the output's method signature.
+        return_args = [v for n, v in named_args if n in outputSpec.args]
+
+    # Get any of input's default arguments that were not passed.
+    passed_arg_names = tuple(kwargs)
+    for name, value in named_args:
+        passed_arg_names += (name, value)
+    defaults = zip(inputSpec.args[::-1], inputSpec.defaults[::-1])
+    full_kwargs = {n: v for n, v in defaults if n not in passed_arg_names}
+    full_kwargs.update(kwargs)
+
+    if outputSpec.varkw:
+        # Only pass all kwargs if the output method accepts **kwargs.
+        return_kwargs = full_kwargs
+    else:
+        # Filter out names that the output method does not accept.
+        all_accepted_names = outputSpec.args[1:] + outputSpec.kwonlyargs
+        return_kwargs = {
+            n: v for n, v in full_kwargs.items() if n in all_accepted_names
+        }
+
+    return return_args, return_kwargs
+
+
+T = TypeVar("T")
+R = TypeVar("R")
+
+
+@dataclass(eq=False)
+class MethodicalInput(object):
+    """
+    An input for a L{MethodicalMachine}.
+    """
+
+    automaton: Automaton[MethodicalState, MethodicalInput, MethodicalOutput] = field(
+        repr=False
+    )
+    method: Callable[..., Any] = field()
+    symbol: str = field(repr=False)
+    collectors: dict[MethodicalState, Callable[[Iterable[T]], R]] = field(
+        default_factory=dict, repr=False
+    )
+
+    argSpec: ArgSpec = field(init=False, repr=False)
+
+    def __post_init__(self) -> None:
+        self.argSpec = _getArgSpec(self.method)
+        assertNoCode(self.method)
+
+    def __get__(self, oself: object, type: None = None) -> object:
+        """
+        Return a function that takes no arguments and returns values returned
+        by output functions produced by the given L{MethodicalInput} in
+        C{oself}'s current state.
+        """
+        transitioner = _transitionerFromInstance(oself, self.symbol, self.automaton)
+
+        @preserveName(self.method)
+        @wraps(self.method)
+        def doInput(*args: object, **kwargs: object) -> object:
+            self.method(oself, *args, **kwargs)
+            previousState = transitioner._state
+            (outputs, outTracer) = transitioner.transition(self)
+            collector = self.collectors[previousState]
+            values = []
+            for output in outputs:
+                if outTracer is not None:
+                    outTracer(output)
+                a, k = _filterArgs(args, kwargs, self.argSpec, output.argSpec)
+                value = output(oself, *a, **k)
+                values.append(value)
+            return collector(values)
+
+        return doInput
+
+    def _name(self) -> str:
+        return self.method.__name__
+
+
+@dataclass(frozen=True)
+class MethodicalOutput(object):
+    """
+    An output for a L{MethodicalMachine}.
+    """
+
+    machine: MethodicalMachine = field(repr=False)
+    method: Callable[..., Any]
+    argSpec: ArgSpec = field(init=False, repr=False, compare=False)
+
+    def __post_init__(self) -> None:
+        self.__dict__["argSpec"] = _getArgSpec(self.method)
+
+    def __get__(self, oself, type=None):
+        """
+        Outputs are private, so raise an exception when we attempt to get one.
+        """
+        raise AttributeError(
+            "{cls}.{method} is a state-machine output method; "
+            "to produce this output, call an input method instead.".format(
+                cls=type.__name__, method=self.method.__name__
+            )
+        )
+
+    def __call__(self, oself, *args, **kwargs):
+        """
+        Call the underlying method.
+        """
+        return self.method(oself, *args, **kwargs)
+
+    def _name(self) -> str:
+        return self.method.__name__
+
+
+StringOutputTracer = Callable[[str], None]
+StringTracer: TypeAlias = "Callable[[str, str, str], StringOutputTracer | None]"
+
+
+def wrapTracer(
+    wrapped: StringTracer | None,
+) -> Tracer[MethodicalState, MethodicalInput, MethodicalOutput] | None:
+    if wrapped is None:
+        return None
+
+    def tracer(
+        state: MethodicalState,
+        input: MethodicalInput,
+        output: MethodicalState,
+    ) -> OutputTracer[MethodicalOutput] | None:
+        result = wrapped(state._name(), input._name(), output._name())
+        if result is not None:
+            return lambda out: result(out._name())
+        return None
+
+    return tracer
+
+
+@dataclass(eq=False)
+class MethodicalTracer(object):
+    automaton: Automaton[MethodicalState, MethodicalInput, MethodicalOutput] = field(
+        repr=False
+    )
+    symbol: str = field(repr=False)
+
+    def __get__(
+        self, oself: object, type: object = None
+    ) -> Callable[[StringTracer], None]:
+        transitioner = _transitionerFromInstance(oself, self.symbol, self.automaton)
+
+        def setTrace(tracer: StringTracer | None) -> None:
+            transitioner.setTrace(wrapTracer(tracer))
+
+        return setTrace
+
+
+counter = count()
+
+
+def gensym():
+    """
+    Create a unique Python identifier.
+    """
+    return "_symbol_" + str(next(counter))
+
+
+class MethodicalMachine(object):
+    """
+    A L{MethodicalMachine} is an interface to an L{Automaton} that uses methods
+    on a class.
+    """
+
+    def __init__(self):
+        self._automaton = Automaton()
+        self._reducers = {}
+        self._symbol = gensym()
+
+    def __get__(self, oself, type=None):
+        """
+        L{MethodicalMachine} is an implementation detail for setting up
+        class-level state; applications should never need to access it on an
+        instance.
+        """
+        if oself is not None:
+            raise AttributeError("MethodicalMachine is an implementation detail.")
+        return self
+
+    @_keywords_only
+    def state(
+        self, initial: bool = False, terminal: bool = False, serialized: Hashable = None
+    ):
+        """
+        Declare a state, possibly an initial state or a terminal state.
+
+        This is a decorator for methods, but it will modify the method so as
+        not to be callable any more.
+
+        @param initial: is this state the initial state?  Only one state on
+            this L{automat.MethodicalMachine} may be an initial state; more
+            than one is an error.
+
+        @param terminal: Is this state a terminal state?  i.e. a state that the
+            machine can end up in?  (This is purely informational at this
+            point.)
+
+        @param serialized: a serializable value to be used to represent this
+            state to external systems.  This value should be hashable; L{str}
+            is a good type to use.
+        """
+
+        def decorator(stateMethod):
+            state = MethodicalState(
+                machine=self, method=stateMethod, serialized=serialized
+            )
+            if initial:
+                self._automaton.initialState = state
+            return state
+
+        return decorator
+
+    @_keywords_only
+    def input(self):
+        """
+        Declare an input.
+
+        This is a decorator for methods.
+        """
+
+        def decorator(inputMethod):
+            return MethodicalInput(
+                automaton=self._automaton, method=inputMethod, symbol=self._symbol
+            )
+
+        return decorator
+
+    @_keywords_only
+    def output(self):
+        """
+        Declare an output.
+
+        This is a decorator for methods.
+
+        This method will be called when the state machine transitions to this
+        state as specified in the decorated `output` method.
+        """
+
+        def decorator(outputMethod):
+            return MethodicalOutput(machine=self, method=outputMethod)
+
+        return decorator
+
+    def _oneTransition(self, startState, inputToken, endState, outputTokens, collector):
+        """
+        See L{MethodicalState.upon}.
+        """
+        # FIXME: tests for all of this (some of it is wrong)
+        # if not isinstance(startState, MethodicalState):
+        #     raise NotImplementedError("start state {} isn't a state"
+        #                               .format(startState))
+        # if not isinstance(inputToken, MethodicalInput):
+        #     raise NotImplementedError("start state {} isn't an input"
+        #                               .format(inputToken))
+        # if not isinstance(endState, MethodicalState):
+        #     raise NotImplementedError("end state {} isn't a state"
+        #                               .format(startState))
+        # for output in outputTokens:
+        #     if not isinstance(endState, MethodicalState):
+        #         raise NotImplementedError("output state {} isn't a state"
+        #                                   .format(endState))
+        self._automaton.addTransition(
+            startState, inputToken, endState, tuple(outputTokens)
+        )
+        inputToken.collectors[startState] = collector
+
+    @_keywords_only
+    def serializer(self):
+        """ """
+
+        def decorator(decoratee):
+            @wraps(decoratee)
+            def serialize(oself):
+                transitioner = _transitionerFromInstance(
+                    oself, self._symbol, self._automaton
+                )
+                return decoratee(oself, transitioner._state.serialized)
+
+            return serialize
+
+        return decorator
+
+    @_keywords_only
+    def unserializer(self):
+        """ """
+
+        def decorator(decoratee):
+            @wraps(decoratee)
+            def unserialize(oself, *args, **kwargs):
+                state = decoratee(oself, *args, **kwargs)
+                mapping = {}
+                for eachState in self._automaton.states():
+                    mapping[eachState.serialized] = eachState
+                transitioner = _transitionerFromInstance(
+                    oself, self._symbol, self._automaton
+                )
+                transitioner._state = mapping[state]
+                return None  # it's on purpose
+
+            return unserialize
+
+        return decorator
+
+    @property
+    def _setTrace(self) -> MethodicalTracer:
+        return MethodicalTracer(self._automaton, self._symbol)
+
+    def asDigraph(self):
+        """
+        Generate a L{graphviz.Digraph} that represents this machine's
+        states and transitions.
+
+        @return: L{graphviz.Digraph} object; for more information, please
+            see the documentation for
+            U{graphviz<https://graphviz.readthedocs.io/>}
+
+        """
+        from ._visualize import makeDigraph
+
+        return makeDigraph(
+            self._automaton,
+            stateAsString=lambda state: state.method.__name__,
+            inputAsString=lambda input: input.method.__name__,
+            outputAsString=lambda output: output.method.__name__,
+        )

.venv/lib/python3.12/site-packages/automat/_runtimeproto.py

@@ -0,0 +1,62 @@
+"""
+Workaround for U{the lack of TypeForm
+<https://github.com/python/mypy/issues/9773>}.
+"""
+
+from __future__ import annotations
+
+import sys
+
+from typing import TYPE_CHECKING, Callable, Protocol, TypeVar
+
+from inspect import signature, Signature
+
+T = TypeVar("T")
+
+ProtocolAtRuntime = Callable[[], T]
+
+
+def runtime_name(x: ProtocolAtRuntime[T]) -> str:
+    return x.__name__
+
+
+from inspect import getmembers, isfunction
+
+emptyProtocolMethods: frozenset[str]
+if not TYPE_CHECKING:
+    emptyProtocolMethods = frozenset(
+        name
+        for name, each in getmembers(type("Example", tuple([Protocol]), {}), isfunction)
+    )
+
+
+def actuallyDefinedProtocolMethods(protocol: object) -> frozenset[str]:
+    """
+    Attempt to ignore implementation details, and get all the methods that the
+    protocol actually defines.
+
+    that includes locally defined methods and also those defined in inherited
+    superclasses.
+    """
+    return (
+        frozenset(name for name, each in getmembers(protocol, isfunction))
+        - emptyProtocolMethods
+    )
+
+
+def _fixAnnotation(method: Callable[..., object], it: object, ann: str) -> None:
+    annotation = getattr(it, ann)
+    if isinstance(annotation, str):
+        setattr(it, ann, eval(annotation, method.__globals__))
+
+
+def _liveSignature(method: Callable[..., object]) -> Signature:
+    """
+    Get a signature with evaluated annotations.
+    """
+    # TODO: could this be replaced with get_type_hints?
+    result = signature(method)
+    for param in result.parameters.values():
+        _fixAnnotation(method, param, "_annotation")
+    _fixAnnotation(method, result, "_return_annotation")
+    return result

.venv/lib/python3.12/site-packages/automat/_test/test_core.py

@@ -0,0 +1,97 @@
+from unittest import TestCase
+
+from .._core import Automaton, NoTransition, Transitioner
+
+
+class CoreTests(TestCase):
+    """
+    Tests for Automat's (currently private, implementation detail) core.
+    """
+
+    def test_NoTransition(self):
+        """
+        A L{NoTransition} exception describes the state and input symbol
+        that caused it.
+        """
+        # NoTransition requires two arguments
+        with self.assertRaises(TypeError):
+            NoTransition()
+
+        state = "current-state"
+        symbol = "transitionless-symbol"
+        noTransitionException = NoTransition(state=state, symbol=symbol)
+
+        self.assertIs(noTransitionException.symbol, symbol)
+
+        self.assertIn(state, str(noTransitionException))
+        self.assertIn(symbol, str(noTransitionException))
+
+    def test_unhandledTransition(self) -> None:
+        """
+        Automaton.unhandledTransition sets the outputs and end-state to be used
+        for all unhandled transitions.
+        """
+        a: Automaton[str, str, str] = Automaton("start")
+        a.addTransition("oops-state", "check", "start", tuple(["checked"]))
+        a.unhandledTransition("oops-state", ["oops-out"])
+        t = Transitioner(a, "start")
+        self.assertEqual(t.transition("check"), (tuple(["oops-out"]), None))
+        self.assertEqual(t.transition("check"), (["checked"], None))
+        self.assertEqual(t.transition("check"), (tuple(["oops-out"]), None))
+
+    def test_noOutputForInput(self):
+        """
+        L{Automaton.outputForInput} raises L{NoTransition} if no
+        transition for that input is defined.
+        """
+        a = Automaton()
+        self.assertRaises(NoTransition, a.outputForInput, "no-state", "no-symbol")
+
+    def test_oneTransition(self):
+        """
+        L{Automaton.addTransition} adds its input symbol to
+        L{Automaton.inputAlphabet}, all its outputs to
+        L{Automaton.outputAlphabet}, and causes L{Automaton.outputForInput} to
+        start returning the new state and output symbols.
+        """
+        a = Automaton()
+        a.addTransition("beginning", "begin", "ending", ["end"])
+        self.assertEqual(a.inputAlphabet(), {"begin"})
+        self.assertEqual(a.outputAlphabet(), {"end"})
+        self.assertEqual(a.outputForInput("beginning", "begin"), ("ending", ["end"]))
+        self.assertEqual(a.states(), {"beginning", "ending"})
+
+    def test_oneTransition_nonIterableOutputs(self):
+        """
+        L{Automaton.addTransition} raises a TypeError when given outputs
+        that aren't iterable and doesn't add any transitions.
+        """
+        a = Automaton()
+        nonIterableOutputs = 1
+        self.assertRaises(
+            TypeError,
+            a.addTransition,
+            "fromState",
+            "viaSymbol",
+            "toState",
+            nonIterableOutputs,
+        )
+        self.assertFalse(a.inputAlphabet())
+        self.assertFalse(a.outputAlphabet())
+        self.assertFalse(a.states())
+        self.assertFalse(a.allTransitions())
+
+    def test_initialState(self):
+        """
+        L{Automaton.initialState} is a descriptor that sets the initial
+        state if it's not yet set, and raises L{ValueError} if it is.
+
+        """
+        a = Automaton()
+        a.initialState = "a state"
+        self.assertEqual(a.initialState, "a state")
+        with self.assertRaises(ValueError):
+            a.initialState = "another state"
+
+
+# FIXME: addTransition for transition that's been added before

.venv/lib/python3.12/site-packages/automat/_test/test_discover.py

@@ -0,0 +1,638 @@
+import operator
+import os
+import shutil
+import sys
+import textwrap
+import tempfile
+from unittest import skipIf, TestCase
+
+
+def isTwistedInstalled():
+    try:
+        __import__("twisted")
+    except ImportError:
+        return False
+    else:
+        return True
+
+
+class _WritesPythonModules(TestCase):
+    """
+    A helper that enables generating Python module test fixtures.
+    """
+
+    def setUp(self):
+        super(_WritesPythonModules, self).setUp()
+
+        from twisted.python.modules import getModule, PythonPath
+        from twisted.python.filepath import FilePath
+
+        self.getModule = getModule
+        self.PythonPath = PythonPath
+        self.FilePath = FilePath
+
+        self.originalSysModules = set(sys.modules.keys())
+        self.savedSysPath = sys.path[:]
+
+        self.pathDir = tempfile.mkdtemp()
+        self.makeImportable(self.pathDir)
+
+    def tearDown(self):
+        super(_WritesPythonModules, self).tearDown()
+
+        sys.path[:] = self.savedSysPath
+        modulesToDelete = sys.modules.keys() - self.originalSysModules
+        for module in modulesToDelete:
+            del sys.modules[module]
+
+        shutil.rmtree(self.pathDir)
+
+    def makeImportable(self, path):
+        sys.path.append(path)
+
+    def writeSourceInto(self, source, path, moduleName):
+        directory = self.FilePath(path)
+
+        module = directory.child(moduleName)
+        # FilePath always opens a file in binary mode - but that will
+        # break on Python 3
+        with open(module.path, "w") as f:
+            f.write(textwrap.dedent(source))
+
+        return self.PythonPath([directory.path])
+
+    def makeModule(self, source, path, moduleName):
+        pythonModuleName, _ = os.path.splitext(moduleName)
+        return self.writeSourceInto(source, path, moduleName)[pythonModuleName]
+
+    def attributesAsDict(self, hasIterAttributes):
+        return {attr.name: attr for attr in hasIterAttributes.iterAttributes()}
+
+    def loadModuleAsDict(self, module):
+        module.load()
+        return self.attributesAsDict(module)
+
+    def makeModuleAsDict(self, source, path, name):
+        return self.loadModuleAsDict(self.makeModule(source, path, name))
+
+
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class OriginalLocationTests(_WritesPythonModules):
+    """
+    Tests that L{isOriginalLocation} detects when a
+    L{PythonAttribute}'s FQPN refers to an object inside the module
+    where it was defined.
+
+    For example: A L{twisted.python.modules.PythonAttribute} with a
+    name of 'foo.bar' that refers to a 'bar' object defined in module
+    'baz' does *not* refer to bar's original location, while a
+    L{PythonAttribute} with a name of 'baz.bar' does.
+
+    """
+
+    def setUp(self):
+        super(OriginalLocationTests, self).setUp()
+        from .._discover import isOriginalLocation
+
+        self.isOriginalLocation = isOriginalLocation
+
+    def test_failsWithNoModule(self):
+        """
+        L{isOriginalLocation} returns False when the attribute refers to an
+        object whose source module cannot be determined.
+        """
+        source = """\
+        class Fake(object):
+            pass
+        hasEmptyModule = Fake()
+        hasEmptyModule.__module__ = None
+        """
+
+        moduleDict = self.makeModuleAsDict(source, self.pathDir, "empty_module_attr.py")
+
+        self.assertFalse(
+            self.isOriginalLocation(moduleDict["empty_module_attr.hasEmptyModule"])
+        )
+
+    def test_failsWithDifferentModule(self):
+        """
+        L{isOriginalLocation} returns False when the attribute refers to
+        an object outside of the module where that object was defined.
+        """
+        originalSource = """\
+        class ImportThisClass(object):
+            pass
+        importThisObject = ImportThisClass()
+        importThisNestingObject = ImportThisClass()
+        importThisNestingObject.nestedObject = ImportThisClass()
+        """
+
+        importingSource = """\
+        from original import (ImportThisClass,
+                              importThisObject,
+                              importThisNestingObject)
+        """
+
+        self.makeModule(originalSource, self.pathDir, "original.py")
+        importingDict = self.makeModuleAsDict(
+            importingSource, self.pathDir, "importing.py"
+        )
+        self.assertFalse(
+            self.isOriginalLocation(importingDict["importing.ImportThisClass"])
+        )
+        self.assertFalse(
+            self.isOriginalLocation(importingDict["importing.importThisObject"])
+        )
+
+        nestingObject = importingDict["importing.importThisNestingObject"]
+        nestingObjectDict = self.attributesAsDict(nestingObject)
+        nestedObject = nestingObjectDict[
+            "importing.importThisNestingObject.nestedObject"
+        ]
+
+        self.assertFalse(self.isOriginalLocation(nestedObject))
+
+    def test_succeedsWithSameModule(self):
+        """
+        L{isOriginalLocation} returns True when the attribute refers to an
+        object inside the module where that object was defined.
+        """
+        mSource = textwrap.dedent(
+            """
+        class ThisClassWasDefinedHere(object):
+            pass
+        anObject = ThisClassWasDefinedHere()
+        aNestingObject = ThisClassWasDefinedHere()
+        aNestingObject.nestedObject = ThisClassWasDefinedHere()
+        """
+        )
+        mDict = self.makeModuleAsDict(mSource, self.pathDir, "m.py")
+        self.assertTrue(self.isOriginalLocation(mDict["m.ThisClassWasDefinedHere"]))
+        self.assertTrue(self.isOriginalLocation(mDict["m.aNestingObject"]))
+
+        nestingObject = mDict["m.aNestingObject"]
+        nestingObjectDict = self.attributesAsDict(nestingObject)
+        nestedObject = nestingObjectDict["m.aNestingObject.nestedObject"]
+
+        self.assertTrue(self.isOriginalLocation(nestedObject))
+
+
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class FindMachinesViaWrapperTests(_WritesPythonModules):
+    """
+    L{findMachinesViaWrapper} recursively yields FQPN,
+    L{MethodicalMachine} pairs in and under a given
+    L{twisted.python.modules.PythonModule} or
+    L{twisted.python.modules.PythonAttribute}.
+    """
+
+    def setUp(self):
+        super(FindMachinesViaWrapperTests, self).setUp()
+        from .._discover import findMachinesViaWrapper
+
+        self.findMachinesViaWrapper = findMachinesViaWrapper
+
+    def test_yieldsMachine(self):
+        """
+        When given a L{twisted.python.modules.PythonAttribute} that refers
+        directly to a L{MethodicalMachine}, L{findMachinesViaWrapper}
+        yields that machine and its FQPN.
+        """
+        source = """\
+        from automat import MethodicalMachine
+
+        rootMachine = MethodicalMachine()
+        """
+
+        moduleDict = self.makeModuleAsDict(source, self.pathDir, "root.py")
+        rootMachine = moduleDict["root.rootMachine"]
+        self.assertIn(
+            ("root.rootMachine", rootMachine.load()),
+            list(self.findMachinesViaWrapper(rootMachine)),
+        )
+
+    def test_yieldsTypeMachine(self) -> None:
+        """
+        When given a L{twisted.python.modules.PythonAttribute} that refers
+        directly to a L{TypeMachine}, L{findMachinesViaWrapper} yields that
+        machine and its FQPN.
+        """
+        source = """\
+        from automat import TypeMachineBuilder
+        from typing import Protocol, Callable
+        class P(Protocol):
+            def method(self) -> None: ...
+        class C:...
+        def buildBuilder() -> Callable[[C], P]:
+            builder = TypeMachineBuilder(P, C)
+            return builder.build()
+        rootMachine = buildBuilder()
+        """
+
+        moduleDict = self.makeModuleAsDict(source, self.pathDir, "root.py")
+        rootMachine = moduleDict["root.rootMachine"]
+        self.assertIn(
+            ("root.rootMachine", rootMachine.load()),
+            list(self.findMachinesViaWrapper(rootMachine)),
+        )
+
+    def test_yieldsMachineInClass(self):
+        """
+        When given a L{twisted.python.modules.PythonAttribute} that refers
+        to a class that contains a L{MethodicalMachine} as a class
+        variable, L{findMachinesViaWrapper} yields that machine and
+        its FQPN.
+        """
+        source = """\
+        from automat import MethodicalMachine
+
+        class PythonClass(object):
+            _classMachine = MethodicalMachine()
+        """
+        moduleDict = self.makeModuleAsDict(source, self.pathDir, "clsmod.py")
+        PythonClass = moduleDict["clsmod.PythonClass"]
+        self.assertIn(
+            ("clsmod.PythonClass._classMachine", PythonClass.load()._classMachine),
+            list(self.findMachinesViaWrapper(PythonClass)),
+        )
+
+    def test_yieldsMachineInNestedClass(self):
+        """
+        When given a L{twisted.python.modules.PythonAttribute} that refers
+        to a nested class that contains a L{MethodicalMachine} as a
+        class variable, L{findMachinesViaWrapper} yields that machine
+        and its FQPN.
+        """
+        source = """\
+        from automat import MethodicalMachine
+
+        class PythonClass(object):
+            class NestedClass(object):
+                _classMachine = MethodicalMachine()
+        """
+        moduleDict = self.makeModuleAsDict(source, self.pathDir, "nestedcls.py")
+
+        PythonClass = moduleDict["nestedcls.PythonClass"]
+        self.assertIn(
+            (
+                "nestedcls.PythonClass.NestedClass._classMachine",
+                PythonClass.load().NestedClass._classMachine,
+            ),
+            list(self.findMachinesViaWrapper(PythonClass)),
+        )
+
+    def test_yieldsMachineInModule(self):
+        """
+        When given a L{twisted.python.modules.PythonModule} that refers to
+        a module that contains a L{MethodicalMachine},
+        L{findMachinesViaWrapper} yields that machine and its FQPN.
+        """
+        source = """\
+        from automat import MethodicalMachine
+
+        rootMachine = MethodicalMachine()
+        """
+        module = self.makeModule(source, self.pathDir, "root.py")
+        rootMachine = self.loadModuleAsDict(module)["root.rootMachine"].load()
+        self.assertIn(
+            ("root.rootMachine", rootMachine), list(self.findMachinesViaWrapper(module))
+        )
+
+    def test_yieldsMachineInClassInModule(self):
+        """
+        When given a L{twisted.python.modules.PythonModule} that refers to
+        the original module of a class containing a
+        L{MethodicalMachine}, L{findMachinesViaWrapper} yields that
+        machine and its FQPN.
+        """
+        source = """\
+        from automat import MethodicalMachine
+
+        class PythonClass(object):
+            _classMachine = MethodicalMachine()
+        """
+        module = self.makeModule(source, self.pathDir, "clsmod.py")
+        PythonClass = self.loadModuleAsDict(module)["clsmod.PythonClass"].load()
+        self.assertIn(
+            ("clsmod.PythonClass._classMachine", PythonClass._classMachine),
+            list(self.findMachinesViaWrapper(module)),
+        )
+
+    def test_yieldsMachineInNestedClassInModule(self):
+        """
+        When given a L{twisted.python.modules.PythonModule} that refers to
+        the original module of a nested class containing a
+        L{MethodicalMachine}, L{findMachinesViaWrapper} yields that
+        machine and its FQPN.
+        """
+        source = """\
+        from automat import MethodicalMachine
+
+        class PythonClass(object):
+            class NestedClass(object):
+                _classMachine = MethodicalMachine()
+        """
+        module = self.makeModule(source, self.pathDir, "nestedcls.py")
+        PythonClass = self.loadModuleAsDict(module)["nestedcls.PythonClass"].load()
+
+        self.assertIn(
+            (
+                "nestedcls.PythonClass.NestedClass._classMachine",
+                PythonClass.NestedClass._classMachine,
+            ),
+            list(self.findMachinesViaWrapper(module)),
+        )
+
+    def test_ignoresImportedClass(self):
+        """
+        When given a L{twisted.python.modules.PythonAttribute} that refers
+        to a class imported from another module, any
+        L{MethodicalMachine}s on that class are ignored.
+
+        This behavior ensures that a machine is only discovered on a
+        class when visiting the module where that class was defined.
+        """
+        originalSource = """
+        from automat import MethodicalMachine
+
+        class PythonClass(object):
+            _classMachine = MethodicalMachine()
+        """
+
+        importingSource = """
+        from original import PythonClass
+        """
+
+        self.makeModule(originalSource, self.pathDir, "original.py")
+        importingModule = self.makeModule(importingSource, self.pathDir, "importing.py")
+
+        self.assertFalse(list(self.findMachinesViaWrapper(importingModule)))
+
+    def test_descendsIntoPackages(self):
+        """
+        L{findMachinesViaWrapper} descends into packages to discover
+        machines.
+        """
+        pythonPath = self.PythonPath([self.pathDir])
+        package = self.FilePath(self.pathDir).child("test_package")
+        package.makedirs()
+        package.child("__init__.py").touch()
+
+        source = """
+        from automat import MethodicalMachine
+
+
+        class PythonClass(object):
+            _classMachine = MethodicalMachine()
+
+
+        rootMachine = MethodicalMachine()
+        """
+        self.makeModule(source, package.path, "module.py")
+
+        test_package = pythonPath["test_package"]
+        machines = sorted(
+            self.findMachinesViaWrapper(test_package), key=operator.itemgetter(0)
+        )
+
+        moduleDict = self.loadModuleAsDict(test_package["module"])
+        rootMachine = moduleDict["test_package.module.rootMachine"].load()
+        PythonClass = moduleDict["test_package.module.PythonClass"].load()
+
+        expectedMachines = sorted(
+            [
+                ("test_package.module.rootMachine", rootMachine),
+                (
+                    "test_package.module.PythonClass._classMachine",
+                    PythonClass._classMachine,
+                ),
+            ],
+            key=operator.itemgetter(0),
+        )
+
+        self.assertEqual(expectedMachines, machines)
+
+    def test_infiniteLoop(self):
+        """
+        L{findMachinesViaWrapper} ignores infinite loops.
+
+        Note this test can't fail - it can only run forever!
+        """
+        source = """
+        class InfiniteLoop(object):
+            pass
+
+        InfiniteLoop.loop = InfiniteLoop
+        """
+        module = self.makeModule(source, self.pathDir, "loop.py")
+        self.assertFalse(list(self.findMachinesViaWrapper(module)))
+
+
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class WrapFQPNTests(TestCase):
+    """
+    Tests that ensure L{wrapFQPN} loads the
+    L{twisted.python.modules.PythonModule} or
+    L{twisted.python.modules.PythonAttribute} for a given FQPN.
+    """
+
+    def setUp(self):
+        from twisted.python.modules import PythonModule, PythonAttribute
+        from .._discover import wrapFQPN, InvalidFQPN, NoModule, NoObject
+
+        self.PythonModule = PythonModule
+        self.PythonAttribute = PythonAttribute
+        self.wrapFQPN = wrapFQPN
+        self.InvalidFQPN = InvalidFQPN
+        self.NoModule = NoModule
+        self.NoObject = NoObject
+
+    def assertModuleWrapperRefersTo(self, moduleWrapper, module):
+        """
+        Assert that a L{twisted.python.modules.PythonModule} refers to a
+        particular Python module.
+        """
+        self.assertIsInstance(moduleWrapper, self.PythonModule)
+        self.assertEqual(moduleWrapper.name, module.__name__)
+        self.assertIs(moduleWrapper.load(), module)
+
+    def assertAttributeWrapperRefersTo(self, attributeWrapper, fqpn, obj):
+        """
+        Assert that a L{twisted.python.modules.PythonAttribute} refers to a
+        particular Python object.
+        """
+        self.assertIsInstance(attributeWrapper, self.PythonAttribute)
+        self.assertEqual(attributeWrapper.name, fqpn)
+        self.assertIs(attributeWrapper.load(), obj)
+
+    def test_failsWithEmptyFQPN(self):
+        """
+        L{wrapFQPN} raises L{InvalidFQPN} when given an empty string.
+        """
+        with self.assertRaises(self.InvalidFQPN):
+            self.wrapFQPN("")
+
+    def test_failsWithBadDotting(self):
+        """ "
+        L{wrapFQPN} raises L{InvalidFQPN} when given a badly-dotted
+        FQPN.  (e.g., x..y).
+        """
+        for bad in (".fails", "fails.", "this..fails"):
+            with self.assertRaises(self.InvalidFQPN):
+                self.wrapFQPN(bad)
+
+    def test_singleModule(self):
+        """
+        L{wrapFQPN} returns a L{twisted.python.modules.PythonModule}
+        referring to the single module a dotless FQPN describes.
+        """
+        import os
+
+        moduleWrapper = self.wrapFQPN("os")
+
+        self.assertIsInstance(moduleWrapper, self.PythonModule)
+        self.assertIs(moduleWrapper.load(), os)
+
+    def test_failsWithMissingSingleModuleOrPackage(self):
+        """
+        L{wrapFQPN} raises L{NoModule} when given a dotless FQPN that does
+        not refer to a module or package.
+        """
+        with self.assertRaises(self.NoModule):
+            self.wrapFQPN("this is not an acceptable name!")
+
+    def test_singlePackage(self):
+        """
+        L{wrapFQPN} returns a L{twisted.python.modules.PythonModule}
+        referring to the single package a dotless FQPN describes.
+        """
+        import xml
+
+        self.assertModuleWrapperRefersTo(self.wrapFQPN("xml"), xml)
+
+    def test_multiplePackages(self):
+        """
+        L{wrapFQPN} returns a L{twisted.python.modules.PythonModule}
+        referring to the deepest package described by dotted FQPN.
+        """
+        import xml.etree
+
+        self.assertModuleWrapperRefersTo(self.wrapFQPN("xml.etree"), xml.etree)
+
+    def test_multiplePackagesFinalModule(self):
+        """
+        L{wrapFQPN} returns a L{twisted.python.modules.PythonModule}
+        referring to the deepest module described by dotted FQPN.
+        """
+        import xml.etree.ElementTree
+
+        self.assertModuleWrapperRefersTo(
+            self.wrapFQPN("xml.etree.ElementTree"), xml.etree.ElementTree
+        )
+
+    def test_singleModuleObject(self):
+        """
+        L{wrapFQPN} returns a L{twisted.python.modules.PythonAttribute}
+        referring to the deepest object an FQPN names, traversing one module.
+        """
+        import os
+
+        self.assertAttributeWrapperRefersTo(
+            self.wrapFQPN("os.path"), "os.path", os.path
+        )
+
+    def test_multiplePackagesObject(self):
+        """
+        L{wrapFQPN} returns a L{twisted.python.modules.PythonAttribute}
+        referring to the deepest object described by an FQPN,
+        descending through several packages.
+        """
+        import xml.etree.ElementTree
+        import automat
+
+        for fqpn, obj in [
+            ("xml.etree.ElementTree.fromstring", xml.etree.ElementTree.fromstring),
+            ("automat.MethodicalMachine.__doc__", automat.MethodicalMachine.__doc__),
+        ]:
+            self.assertAttributeWrapperRefersTo(self.wrapFQPN(fqpn), fqpn, obj)
+
+    def test_failsWithMultiplePackagesMissingModuleOrPackage(self):
+        """
+        L{wrapFQPN} raises L{NoObject} when given an FQPN that contains a
+        missing attribute, module, or package.
+        """
+        for bad in ("xml.etree.nope!", "xml.etree.nope!.but.the.rest.is.believable"):
+            with self.assertRaises(self.NoObject):
+                self.wrapFQPN(bad)
+
+
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class FindMachinesIntegrationTests(_WritesPythonModules):
+    """
+    Integration tests to check that L{findMachines} yields all
+    machines discoverable at or below an FQPN.
+    """
+
+    SOURCE = """
+    from automat import MethodicalMachine
+
+    class PythonClass(object):
+        _machine = MethodicalMachine()
+        ignored = "i am ignored"
+
+    rootLevel = MethodicalMachine()
+
+    ignored = "i am ignored"
+    """
+
+    def setUp(self):
+        super(FindMachinesIntegrationTests, self).setUp()
+        from .._discover import findMachines
+
+        self.findMachines = findMachines
+
+        packageDir = self.FilePath(self.pathDir).child("test_package")
+        packageDir.makedirs()
+        self.pythonPath = self.PythonPath([self.pathDir])
+        self.writeSourceInto(self.SOURCE, packageDir.path, "__init__.py")
+
+        subPackageDir = packageDir.child("subpackage")
+        subPackageDir.makedirs()
+        subPackageDir.child("__init__.py").touch()
+
+        self.makeModule(self.SOURCE, subPackageDir.path, "module.py")
+
+        self.packageDict = self.loadModuleAsDict(self.pythonPath["test_package"])
+        self.moduleDict = self.loadModuleAsDict(
+            self.pythonPath["test_package"]["subpackage"]["module"]
+        )
+
+    def test_discoverAll(self):
+        """
+        Given a top-level package FQPN, L{findMachines} discovers all
+        L{MethodicalMachine} instances in and below it.
+        """
+        machines = sorted(self.findMachines("test_package"), key=operator.itemgetter(0))
+
+        tpRootLevel = self.packageDict["test_package.rootLevel"].load()
+        tpPythonClass = self.packageDict["test_package.PythonClass"].load()
+
+        mRLAttr = self.moduleDict["test_package.subpackage.module.rootLevel"]
+        mRootLevel = mRLAttr.load()
+        mPCAttr = self.moduleDict["test_package.subpackage.module.PythonClass"]
+        mPythonClass = mPCAttr.load()
+
+        expectedMachines = sorted(
+            [
+                ("test_package.rootLevel", tpRootLevel),
+                ("test_package.PythonClass._machine", tpPythonClass._machine),
+                ("test_package.subpackage.module.rootLevel", mRootLevel),
+                (
+                    "test_package.subpackage.module.PythonClass._machine",
+                    mPythonClass._machine,
+                ),
+            ],
+            key=operator.itemgetter(0),
+        )
+
+        self.assertEqual(expectedMachines, machines)

.venv/lib/python3.12/site-packages/automat/_test/test_methodical.py

@@ -0,0 +1,717 @@
+"""
+Tests for the public interface of Automat.
+"""
+
+from functools import reduce
+from unittest import TestCase
+
+from automat._methodical import ArgSpec, _getArgNames, _getArgSpec, _filterArgs
+from .. import MethodicalMachine, NoTransition
+from .. import _methodical
+
+
+class MethodicalTests(TestCase):
+    """
+    Tests for L{MethodicalMachine}.
+    """
+
+    def test_oneTransition(self):
+        """
+        L{MethodicalMachine} provides a way for you to declare a state machine
+        with inputs, outputs, and states as methods.  When you have declared an
+        input, an output, and a state, calling the input method in that state
+        will produce the specified output.
+        """
+
+        class Machination(object):
+            machine = MethodicalMachine()
+
+            @machine.input()
+            def anInput(self):
+                "an input"
+
+            @machine.output()
+            def anOutput(self):
+                "an output"
+                return "an-output-value"
+
+            @machine.output()
+            def anotherOutput(self):
+                "another output"
+                return "another-output-value"
+
+            @machine.state(initial=True)
+            def anState(self):
+                "a state"
+
+            @machine.state()
+            def anotherState(self):
+                "another state"
+
+            anState.upon(anInput, enter=anotherState, outputs=[anOutput])
+            anotherState.upon(anInput, enter=anotherState, outputs=[anotherOutput])
+
+        m = Machination()
+        self.assertEqual(m.anInput(), ["an-output-value"])
+        self.assertEqual(m.anInput(), ["another-output-value"])
+
+    def test_machineItselfIsPrivate(self):
+        """
+        L{MethodicalMachine} is an implementation detail.  If you attempt to
+        access it on an instance of your class, you will get an exception.
+        However, since tools may need to access it for the purposes of, for
+        example, visualization, you may access it on the class itself.
+        """
+        expectedMachine = MethodicalMachine()
+
+        class Machination(object):
+            machine = expectedMachine
+
+        machination = Machination()
+        with self.assertRaises(AttributeError) as cm:
+            machination.machine
+        self.assertIn(
+            "MethodicalMachine is an implementation detail", str(cm.exception)
+        )
+        self.assertIs(Machination.machine, expectedMachine)
+
+    def test_outputsArePrivate(self):
+        """
+        One of the benefits of using a state machine is that your output method
+        implementations don't need to take invalid state transitions into
+        account - the methods simply won't be called.  This property would be
+        broken if client code called output methods directly, so output methods
+        are not directly visible under their names.
+        """
+
+        class Machination(object):
+            machine = MethodicalMachine()
+            counter = 0
+
+            @machine.input()
+            def anInput(self):
+                "an input"
+
+            @machine.output()
+            def anOutput(self):
+                self.counter += 1
+
+            @machine.state(initial=True)
+            def state(self):
+                "a machine state"
+
+            state.upon(anInput, enter=state, outputs=[anOutput])
+
+        mach1 = Machination()
+        mach1.anInput()
+        self.assertEqual(mach1.counter, 1)
+        mach2 = Machination()
+        with self.assertRaises(AttributeError) as cm:
+            mach2.anOutput
+        self.assertEqual(mach2.counter, 0)
+
+        self.assertIn(
+            "Machination.anOutput is a state-machine output method; to "
+            "produce this output, call an input method instead.",
+            str(cm.exception),
+        )
+
+    def test_multipleMachines(self):
+        """
+        Two machines may co-exist happily on the same instance; they don't
+        interfere with each other.
+        """
+
+        class MultiMach(object):
+            a = MethodicalMachine()
+            b = MethodicalMachine()
+
+            @a.input()
+            def inputA(self):
+                "input A"
+
+            @b.input()
+            def inputB(self):
+                "input B"
+
+            @a.state(initial=True)
+            def initialA(self):
+                "initial A"
+
+            @b.state(initial=True)
+            def initialB(self):
+                "initial B"
+
+            @a.output()
+            def outputA(self):
+                return "A"
+
+            @b.output()
+            def outputB(self):
+                return "B"
+
+            initialA.upon(inputA, initialA, [outputA])
+            initialB.upon(inputB, initialB, [outputB])
+
+        mm = MultiMach()
+        self.assertEqual(mm.inputA(), ["A"])
+        self.assertEqual(mm.inputB(), ["B"])
+
+    def test_collectOutputs(self):
+        """
+        Outputs can be combined with the "collector" argument to "upon".
+        """
+        import operator
+
+        class Machine(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                "an input"
+
+            @m.output()
+            def outputA(self):
+                return "A"
+
+            @m.output()
+            def outputB(self):
+                return "B"
+
+            @m.state(initial=True)
+            def state(self):
+                "a state"
+
+            state.upon(
+                input,
+                state,
+                [outputA, outputB],
+                collector=lambda x: reduce(operator.add, x),
+            )
+
+        m = Machine()
+        self.assertEqual(m.input(), "AB")
+
+    def test_methodName(self):
+        """
+        Input methods preserve their declared names.
+        """
+
+        class Mech(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def declaredInputName(self):
+                "an input"
+
+            @m.state(initial=True)
+            def aState(self):
+                "state"
+
+        m = Mech()
+        with self.assertRaises(TypeError) as cm:
+            m.declaredInputName("too", "many", "arguments")
+        self.assertIn("declaredInputName", str(cm.exception))
+
+    def test_inputWithArguments(self):
+        """
+        If an input takes an argument, it will pass that along to its output.
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self, x, y=1):
+                "an input"
+
+            @m.state(initial=True)
+            def state(self):
+                "a state"
+
+            @m.output()
+            def output(self, x, y=1):
+                self._x = x
+                return x + y
+
+            state.upon(input, state, [output])
+
+        m = Mechanism()
+        self.assertEqual(m.input(3), [4])
+        self.assertEqual(m._x, 3)
+
+    def test_outputWithSubsetOfArguments(self):
+        """
+        Inputs pass arguments that output will accept.
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self, x, y=1):
+                "an input"
+
+            @m.state(initial=True)
+            def state(self):
+                "a state"
+
+            @m.output()
+            def outputX(self, x):
+                self._x = x
+                return x
+
+            @m.output()
+            def outputY(self, y):
+                self._y = y
+                return y
+
+            @m.output()
+            def outputNoArgs(self):
+                return None
+
+            state.upon(input, state, [outputX, outputY, outputNoArgs])
+
+        m = Mechanism()
+
+        # Pass x as positional argument.
+        self.assertEqual(m.input(3), [3, 1, None])
+        self.assertEqual(m._x, 3)
+        self.assertEqual(m._y, 1)
+
+        # Pass x as key word argument.
+        self.assertEqual(m.input(x=4), [4, 1, None])
+        self.assertEqual(m._x, 4)
+        self.assertEqual(m._y, 1)
+
+        # Pass y as positional argument.
+        self.assertEqual(m.input(6, 3), [6, 3, None])
+        self.assertEqual(m._x, 6)
+        self.assertEqual(m._y, 3)
+
+        # Pass y as key word argument.
+        self.assertEqual(m.input(5, y=2), [5, 2, None])
+        self.assertEqual(m._x, 5)
+        self.assertEqual(m._y, 2)
+
+    def test_inputFunctionsMustBeEmpty(self):
+        """
+        The wrapped input function must have an empty body.
+        """
+        # input functions are executed to assert that the signature matches,
+        # but their body must be empty
+
+        _methodical._empty()  # chase coverage
+        _methodical._docstring()
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+            with self.assertRaises(ValueError) as cm:
+
+                @m.input()
+                def input(self):
+                    "an input"
+                    list()  # pragma: no cover
+
+            self.assertEqual(str(cm.exception), "function body must be empty")
+
+        # all three of these cases should be valid. Functions/methods with
+        # docstrings produce slightly different bytecode than ones without.
+
+        class MechanismWithDocstring(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                "an input"
+
+            @m.state(initial=True)
+            def start(self):
+                "starting state"
+
+            start.upon(input, enter=start, outputs=[])
+
+        MechanismWithDocstring().input()
+
+        class MechanismWithPass(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                pass
+
+            @m.state(initial=True)
+            def start(self):
+                "starting state"
+
+            start.upon(input, enter=start, outputs=[])
+
+        MechanismWithPass().input()
+
+        class MechanismWithDocstringAndPass(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                "an input"
+                pass
+
+            @m.state(initial=True)
+            def start(self):
+                "starting state"
+
+            start.upon(input, enter=start, outputs=[])
+
+        MechanismWithDocstringAndPass().input()
+
+        class MechanismReturnsNone(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                return None
+
+            @m.state(initial=True)
+            def start(self):
+                "starting state"
+
+            start.upon(input, enter=start, outputs=[])
+
+        MechanismReturnsNone().input()
+
+        class MechanismWithDocstringAndReturnsNone(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                "an input"
+                return None
+
+            @m.state(initial=True)
+            def start(self):
+                "starting state"
+
+            start.upon(input, enter=start, outputs=[])
+
+        MechanismWithDocstringAndReturnsNone().input()
+
+    def test_inputOutputMismatch(self):
+        """
+        All the argument lists of the outputs for a given input must match; if
+        one does not the call to C{upon} will raise a C{TypeError}.
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def nameOfInput(self, a):
+                "an input"
+
+            @m.output()
+            def outputThatMatches(self, a):
+                "an output that matches"
+
+            @m.output()
+            def outputThatDoesntMatch(self, b):
+                "an output that doesn't match"
+
+            @m.state()
+            def state(self):
+                "a state"
+
+            with self.assertRaises(TypeError) as cm:
+                state.upon(
+                    nameOfInput, state, [outputThatMatches, outputThatDoesntMatch]
+                )
+            self.assertIn("nameOfInput", str(cm.exception))
+            self.assertIn("outputThatDoesntMatch", str(cm.exception))
+
+    def test_stateLoop(self):
+        """
+        It is possible to write a self-loop by omitting "enter"
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def input(self):
+                "an input"
+
+            @m.input()
+            def say_hi(self):
+                "an input"
+
+            @m.output()
+            def _start_say_hi(self):
+                return "hi"
+
+            @m.state(initial=True)
+            def start(self):
+                "a state"
+
+            def said_hi(self):
+                "a state with no inputs"
+
+            start.upon(input, outputs=[])
+            start.upon(say_hi, outputs=[_start_say_hi])
+
+        a_mechanism = Mechanism()
+        [a_greeting] = a_mechanism.say_hi()
+        self.assertEqual(a_greeting, "hi")
+
+    def test_defaultOutputs(self):
+        """
+        It is possible to write a transition with no outputs
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            @m.input()
+            def finish(self):
+                "final transition"
+
+            @m.state(initial=True)
+            def start(self):
+                "a start state"
+
+            @m.state()
+            def finished(self):
+                "a final state"
+
+            start.upon(finish, enter=finished)
+
+        Mechanism().finish()
+
+    def test_getArgNames(self):
+        """
+        Type annotations should be included in the set of
+        """
+        spec = ArgSpec(
+            args=("a", "b"),
+            varargs=None,
+            varkw=None,
+            defaults=None,
+            kwonlyargs=(),
+            kwonlydefaults=None,
+            annotations=(("a", int), ("b", str)),
+        )
+        self.assertEqual(
+            _getArgNames(spec),
+            {"a", "b", ("a", int), ("b", str)},
+        )
+
+    def test_filterArgs(self):
+        """
+        filterArgs() should not filter the `args` parameter
+        if outputSpec accepts `*args`.
+        """
+        inputSpec = _getArgSpec(lambda *args, **kwargs: None)
+        outputSpec = _getArgSpec(lambda *args, **kwargs: None)
+        argsIn = ()
+        argsOut, _ = _filterArgs(argsIn, {}, inputSpec, outputSpec)
+        self.assertIs(argsIn, argsOut)
+
+    def test_multipleInitialStatesFailure(self):
+        """
+        A L{MethodicalMachine} can only have one initial state.
+        """
+
+        class WillFail(object):
+            m = MethodicalMachine()
+
+            @m.state(initial=True)
+            def firstInitialState(self):
+                "The first initial state -- this is OK."
+
+            with self.assertRaises(ValueError):
+
+                @m.state(initial=True)
+                def secondInitialState(self):
+                    "The second initial state -- results in a ValueError."
+
+    def test_multipleTransitionsFailure(self):
+        """
+        A L{MethodicalMachine} can only have one transition per start/event
+        pair.
+        """
+
+        class WillFail(object):
+            m = MethodicalMachine()
+
+            @m.state(initial=True)
+            def start(self):
+                "We start here."
+
+            @m.state()
+            def end(self):
+                "Rainbows end."
+
+            @m.input()
+            def event(self):
+                "An event."
+
+            start.upon(event, enter=end, outputs=[])
+            with self.assertRaises(ValueError):
+                start.upon(event, enter=end, outputs=[])
+
+    def test_badTransitionForCurrentState(self):
+        """
+        Calling any input method that lacks a transition for the machine's
+        current state raises an informative L{NoTransition}.
+        """
+
+        class OnlyOnePath(object):
+            m = MethodicalMachine()
+
+            @m.state(initial=True)
+            def start(self):
+                "Start state."
+
+            @m.state()
+            def end(self):
+                "End state."
+
+            @m.input()
+            def advance(self):
+                "Move from start to end."
+
+            @m.input()
+            def deadEnd(self):
+                "A transition from nowhere to nowhere."
+
+            start.upon(advance, end, [])
+
+        machine = OnlyOnePath()
+        with self.assertRaises(NoTransition) as cm:
+            machine.deadEnd()
+        self.assertIn("deadEnd", str(cm.exception))
+        self.assertIn("start", str(cm.exception))
+        machine.advance()
+        with self.assertRaises(NoTransition) as cm:
+            machine.deadEnd()
+        self.assertIn("deadEnd", str(cm.exception))
+        self.assertIn("end", str(cm.exception))
+
+    def test_saveState(self):
+        """
+        L{MethodicalMachine.serializer} is a decorator that modifies its
+        decoratee's signature to take a "state" object as its first argument,
+        which is the "serialized" argument to the L{MethodicalMachine.state}
+        decorator.
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            def __init__(self):
+                self.value = 1
+
+            @m.state(serialized="first-state", initial=True)
+            def first(self):
+                "First state."
+
+            @m.state(serialized="second-state")
+            def second(self):
+                "Second state."
+
+            @m.serializer()
+            def save(self, state):
+                return {
+                    "machine-state": state,
+                    "some-value": self.value,
+                }
+
+        self.assertEqual(
+            Mechanism().save(),
+            {
+                "machine-state": "first-state",
+                "some-value": 1,
+            },
+        )
+
+    def test_restoreState(self):
+        """
+        L{MethodicalMachine.unserializer} decorates a function that becomes a
+        machine-state unserializer; its return value is mapped to the
+        C{serialized} parameter to C{state}, and the L{MethodicalMachine}
+        associated with that instance's state is updated to that state.
+        """
+
+        class Mechanism(object):
+            m = MethodicalMachine()
+
+            def __init__(self):
+                self.value = 1
+                self.ranOutput = False
+
+            @m.state(serialized="first-state", initial=True)
+            def first(self):
+                "First state."
+
+            @m.state(serialized="second-state")
+            def second(self):
+                "Second state."
+
+            @m.input()
+            def input(self):
+                "an input"
+
+            @m.output()
+            def output(self):
+                self.value = 2
+                self.ranOutput = True
+                return 1
+
+            @m.output()
+            def output2(self):
+                return 2
+
+            first.upon(input, second, [output], collector=lambda x: list(x)[0])
+            second.upon(input, second, [output2], collector=lambda x: list(x)[0])
+
+            @m.serializer()
+            def save(self, state):
+                return {
+                    "machine-state": state,
+                    "some-value": self.value,
+                }
+
+            @m.unserializer()
+            def _restore(self, blob):
+                self.value = blob["some-value"]
+                return blob["machine-state"]
+
+            @classmethod
+            def fromBlob(cls, blob):
+                self = cls()
+                self._restore(blob)
+                return self
+
+        m1 = Mechanism()
+        m1.input()
+        blob = m1.save()
+        m2 = Mechanism.fromBlob(blob)
+        self.assertEqual(m2.ranOutput, False)
+        self.assertEqual(m2.input(), 2)
+        self.assertEqual(
+            m2.save(),
+            {
+                "machine-state": "second-state",
+                "some-value": 2,
+            },
+        )
+
+
+# FIXME: error for wrong types on any call to _oneTransition
+# FIXME: better public API for .upon; maybe a context manager?
+# FIXME: when transitions are defined, validate that we can always get to
+# terminal? do we care about this?
+# FIXME: implementation (and use-case/example) for passing args from in to out
+
+# FIXME: possibly these need some kind of support from core
+# FIXME: wildcard state (in all states, when input X, emit Y and go to Z)
+# FIXME: wildcard input (in state X, when any input, emit Y and go to Z)
+# FIXME: combined wildcards (in any state for any input, emit Y go to Z)

.venv/lib/python3.12/site-packages/automat/_test/test_trace.py

@@ -0,0 +1,142 @@
+from unittest import TestCase
+from .._methodical import MethodicalMachine
+
+
+class SampleObject(object):
+    mm = MethodicalMachine()
+
+    @mm.state(initial=True)
+    def begin(self):
+        "initial state"
+
+    @mm.state()
+    def middle(self):
+        "middle state"
+
+    @mm.state()
+    def end(self):
+        "end state"
+
+    @mm.input()
+    def go1(self):
+        "sample input"
+
+    @mm.input()
+    def go2(self):
+        "sample input"
+
+    @mm.input()
+    def back(self):
+        "sample input"
+
+    @mm.output()
+    def out(self):
+        "sample output"
+
+    setTrace = mm._setTrace
+
+    begin.upon(go1, middle, [out])
+    middle.upon(go2, end, [out])
+    end.upon(back, middle, [])
+    middle.upon(back, begin, [])
+
+
+class TraceTests(TestCase):
+    def test_only_inputs(self):
+        traces = []
+
+        def tracer(old_state, input, new_state):
+            traces.append((old_state, input, new_state))
+            return None  # "I only care about inputs, not outputs"
+
+        s = SampleObject()
+        s.setTrace(tracer)
+
+        s.go1()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle"),
+            ],
+        )
+
+        s.go2()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle"),
+                ("middle", "go2", "end"),
+            ],
+        )
+        s.setTrace(None)
+        s.back()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle"),
+                ("middle", "go2", "end"),
+            ],
+        )
+        s.go2()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle"),
+                ("middle", "go2", "end"),
+            ],
+        )
+
+    def test_inputs_and_outputs(self):
+        traces = []
+
+        def tracer(old_state, input, new_state):
+            traces.append((old_state, input, new_state, None))
+
+            def trace_outputs(output):
+                traces.append((old_state, input, new_state, output))
+
+            return trace_outputs  # "I care about outputs too"
+
+        s = SampleObject()
+        s.setTrace(tracer)
+
+        s.go1()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle", None),
+                ("begin", "go1", "middle", "out"),
+            ],
+        )
+
+        s.go2()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle", None),
+                ("begin", "go1", "middle", "out"),
+                ("middle", "go2", "end", None),
+                ("middle", "go2", "end", "out"),
+            ],
+        )
+        s.setTrace(None)
+        s.back()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle", None),
+                ("begin", "go1", "middle", "out"),
+                ("middle", "go2", "end", None),
+                ("middle", "go2", "end", "out"),
+            ],
+        )
+        s.go2()
+        self.assertEqual(
+            traces,
+            [
+                ("begin", "go1", "middle", None),
+                ("begin", "go1", "middle", "out"),
+                ("middle", "go2", "end", None),
+                ("middle", "go2", "end", "out"),
+            ],
+        )

.venv/lib/python3.12/site-packages/automat/_test/test_type_based.py

@@ -0,0 +1,534 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Callable, Generic, List, Protocol, TypeVar
+from unittest import TestCase, skipIf
+
+from .. import AlreadyBuiltError, NoTransition, TypeMachineBuilder, pep614
+
+try:
+    from zope.interface import Interface, implementer  # type:ignore[import-untyped]
+except ImportError:
+    hasInterface = False
+else:
+    hasInterface = True
+
+    class ISomething(Interface):
+        def something() -> int: ...  # type:ignore[misc,empty-body]
+
+
+T = TypeVar("T")
+
+
+class ProtocolForTesting(Protocol):
+
+    def change(self) -> None:
+        "Switch to the other state."
+
+    def value(self) -> int:
+        "Give a value specific to the given state."
+
+
+class ArgTaker(Protocol):
+    def takeSomeArgs(self, arg1: int = 0, arg2: str = "") -> None: ...
+    def value(self) -> int: ...
+
+
+class NoOpCore:
+    "Just an object, you know?"
+
+
+@dataclass
+class Gen(Generic[T]):
+    t: T
+
+
+def buildTestBuilder() -> tuple[
+    TypeMachineBuilder[ProtocolForTesting, NoOpCore],
+    Callable[[NoOpCore], ProtocolForTesting],
+]:
+    builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+    first = builder.state("first")
+    second = builder.state("second")
+
+    first.upon(ProtocolForTesting.change).to(second).returns(None)
+    second.upon(ProtocolForTesting.change).to(first).returns(None)
+
+    @pep614(first.upon(ProtocolForTesting.value).loop())
+    def firstValue(machine: ProtocolForTesting, core: NoOpCore) -> int:
+        return 3
+
+    @pep614(second.upon(ProtocolForTesting.value).loop())
+    def secondValue(machine: ProtocolForTesting, core: NoOpCore) -> int:
+        return 4
+
+    return builder, builder.build()
+
+
+builder, machineFactory = buildTestBuilder()
+
+
+def needsSomething(proto: ProtocolForTesting, core: NoOpCore, value: str) -> int:
+    "we need data to build this state"
+    return 3  # pragma: no cover
+
+
+def needsNothing(proto: ArgTaker, core: NoOpCore) -> str:
+    return "state-specific data"  # pragma: no cover
+
+
+class SimpleProtocol(Protocol):
+    def method(self) -> None:
+        "A method"
+
+
+class Counter(Protocol):
+    def start(self) -> None:
+        "enter the counting state"
+
+    def increment(self) -> None:
+        "increment the counter"
+
+    def stop(self) -> int:
+        "stop"
+
+
+@dataclass
+class Count:
+    value: int = 0
+
+
+class TypeMachineTests(TestCase):
+
+    def test_oneTransition(self) -> None:
+
+        machine = machineFactory(NoOpCore())
+
+        self.assertEqual(machine.value(), 3)
+        machine.change()
+        self.assertEqual(machine.value(), 4)
+        self.assertEqual(machine.value(), 4)
+        machine.change()
+        self.assertEqual(machine.value(), 3)
+
+    def test_stateSpecificData(self) -> None:
+
+        builder = TypeMachineBuilder(Counter, NoOpCore)
+        initial = builder.state("initial")
+        counting = builder.state("counting", lambda machine, core: Count())
+        initial.upon(Counter.start).to(counting).returns(None)
+
+        @pep614(counting.upon(Counter.increment).loop())
+        def incf(counter: Counter, core: NoOpCore, count: Count) -> None:
+            count.value += 1
+
+        @pep614(counting.upon(Counter.stop).to(initial))
+        def finish(counter: Counter, core: NoOpCore, count: Count) -> int:
+            return count.value
+
+        machineFactory = builder.build()
+        machine = machineFactory(NoOpCore())
+        machine.start()
+        machine.increment()
+        machine.increment()
+        self.assertEqual(machine.stop(), 2)
+        machine.start()
+        machine.increment()
+        self.assertEqual(machine.stop(), 1)
+
+    def test_stateSpecificDataWithoutData(self) -> None:
+        """
+        To facilitate common implementations of transition behavior methods,
+        sometimes you want to implement a transition within a data state
+        without taking a data parameter.  To do this, pass the 'nodata=True'
+        parameter to 'upon'.
+        """
+        builder = TypeMachineBuilder(Counter, NoOpCore)
+        initial = builder.state("initial")
+        counting = builder.state("counting", lambda machine, core: Count())
+        startCalls = []
+
+        @pep614(initial.upon(Counter.start).to(counting))
+        @pep614(counting.upon(Counter.start, nodata=True).loop())
+        def start(counter: Counter, core: NoOpCore) -> None:
+            startCalls.append("started!")
+
+        @pep614(counting.upon(Counter.increment).loop())
+        def incf(counter: Counter, core: NoOpCore, count: Count) -> None:
+            count.value += 1
+
+        @pep614(counting.upon(Counter.stop).to(initial))
+        def finish(counter: Counter, core: NoOpCore, count: Count) -> int:
+            return count.value
+
+        machineFactory = builder.build()
+        machine = machineFactory(NoOpCore())
+        machine.start()
+        self.assertEqual(len(startCalls), 1)
+        machine.start()
+        self.assertEqual(len(startCalls), 2)
+        machine.increment()
+        self.assertEqual(machine.stop(), 1)
+
+    def test_incompleteTransitionDefinition(self) -> None:
+        builder = TypeMachineBuilder(SimpleProtocol, NoOpCore)
+        sample = builder.state("sample")
+        sample.upon(SimpleProtocol.method).loop()  # oops, no '.returns(None)'
+        with self.assertRaises(ValueError) as raised:
+            builder.build()
+        self.assertIn(
+            "incomplete transition from sample to sample upon SimpleProtocol.method",
+            str(raised.exception),
+        )
+
+    def test_dataToData(self) -> None:
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+
+        @dataclass
+        class Data1:
+            value: int
+
+        @dataclass
+        class Data2:
+            stuff: List[str]
+
+        initial = builder.state("initial")
+        counting = builder.state("counting", lambda proto, core: Data1(1))
+        appending = builder.state("appending", lambda proto, core: Data2([]))
+
+        initial.upon(ProtocolForTesting.change).to(counting).returns(None)
+
+        @pep614(counting.upon(ProtocolForTesting.value).loop())
+        def countup(p: ProtocolForTesting, c: NoOpCore, d: Data1) -> int:
+            d.value *= 2
+            return d.value
+
+        counting.upon(ProtocolForTesting.change).to(appending).returns(None)
+
+        @pep614(appending.upon(ProtocolForTesting.value).loop())
+        def appendup(p: ProtocolForTesting, c: NoOpCore, d: Data2) -> int:
+            d.stuff.extend("abc")
+            return len(d.stuff)
+
+        machineFactory = builder.build()
+        machine = machineFactory(NoOpCore())
+        machine.change()
+        self.assertEqual(machine.value(), 2)
+        self.assertEqual(machine.value(), 4)
+        machine.change()
+        self.assertEqual(machine.value(), 3)
+        self.assertEqual(machine.value(), 6)
+
+    def test_dataFactoryArgs(self) -> None:
+        """
+        Any data factory that takes arguments will constrain the allowed
+        signature of all protocol methods that transition into that state.
+        """
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+        initial = builder.state("initial")
+        data = builder.state("data", needsSomething)
+        data2 = builder.state("data2", needsSomething)
+        # toState = initial.to(data)
+
+        # 'assertions' in the form of expected type errors:
+        # (no data -> data)
+        uponNoData = initial.upon(ProtocolForTesting.change)
+        uponNoData.to(data)  # type:ignore[arg-type]
+
+        # (data -> data)
+        uponData = data.upon(ProtocolForTesting.change)
+        uponData.to(data2)  # type:ignore[arg-type]
+
+    def test_dataFactoryNoArgs(self) -> None:
+        """
+        Inverse of C{test_dataFactoryArgs} where the data factory specifically
+        does I{not} take arguments, but the input specified does.
+        """
+        builder = TypeMachineBuilder(ArgTaker, NoOpCore)
+        initial = builder.state("initial")
+        data = builder.state("data", needsNothing)
+        (
+            initial.upon(ArgTaker.takeSomeArgs)
+            .to(data)  # type:ignore[arg-type]
+            .returns(None)
+        )
+
+    def test_invalidTransition(self) -> None:
+        """
+        Invalid transitions raise a NoTransition exception.
+        """
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+        builder.state("initial")
+        factory = builder.build()
+        machine = factory(NoOpCore())
+        with self.assertRaises(NoTransition):
+            machine.change()
+
+    def test_reentrancy(self) -> None:
+        """
+        During the execution of a transition behavior implementation function,
+        you may invoke other methods on your state machine.  However, the
+        execution of the behavior of those methods will be deferred until the
+        current behavior method is done executing.  In order to implement that
+        deferral, we restrict the set of methods that can be invoked to those
+        that return None.
+
+        @note: it may be possible to implement deferral via Awaitables or
+            Deferreds later, but we are starting simple.
+        """
+
+        class SomeMethods(Protocol):
+            def start(self) -> None:
+                "Start the machine."
+
+            def later(self) -> None:
+                "Do some deferrable work."
+
+        builder = TypeMachineBuilder(SomeMethods, NoOpCore)
+
+        initial = builder.state("initial")
+        second = builder.state("second")
+
+        order = []
+
+        @pep614(initial.upon(SomeMethods.start).to(second))
+        def startup(methods: SomeMethods, core: NoOpCore) -> None:
+            order.append("startup")
+            methods.later()
+            order.append("startup done")
+
+        @pep614(second.upon(SomeMethods.later).loop())
+        def later(methods: SomeMethods, core: NoOpCore) -> None:
+            order.append("later")
+
+        machineFactory = builder.build()
+        machine = machineFactory(NoOpCore())
+        machine.start()
+        self.assertEqual(order, ["startup", "startup done", "later"])
+
+    def test_reentrancyNotNoneError(self) -> None:
+        class SomeMethods(Protocol):
+            def start(self) -> None:
+                "Start the machine."
+
+            def later(self) -> int:
+                "Do some deferrable work."
+
+        builder = TypeMachineBuilder(SomeMethods, NoOpCore)
+
+        initial = builder.state("initial")
+        second = builder.state("second")
+
+        order = []
+
+        @pep614(initial.upon(SomeMethods.start).to(second))
+        def startup(methods: SomeMethods, core: NoOpCore) -> None:
+            order.append("startup")
+            methods.later()
+            order.append("startup done")  # pragma: no cover
+
+        @pep614(second.upon(SomeMethods.later).loop())
+        def later(methods: SomeMethods, core: NoOpCore) -> int:
+            order.append("later")
+            return 3
+
+        machineFactory = builder.build()
+        machine = machineFactory(NoOpCore())
+        with self.assertRaises(RuntimeError):
+            machine.start()
+        self.assertEqual(order, ["startup"])
+        # We do actually do the state transition, which happens *before* the
+        # output is generated; TODO: maybe we should have exception handling
+        # that transitions into an error state that requires explicit recovery?
+        self.assertEqual(machine.later(), 3)
+        self.assertEqual(order, ["startup", "later"])
+
+    def test_buildLock(self) -> None:
+        """
+        ``.build()`` locks the builder so it can no longer be modified.
+        """
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+        state = builder.state("test-state")
+        state2 = builder.state("state2")
+        state3 = builder.state("state3")
+        upon = state.upon(ProtocolForTesting.change)
+        to = upon.to(state2)
+        to2 = upon.to(state3)
+        to.returns(None)
+        with self.assertRaises(ValueError) as ve:
+            to2.returns(None)
+        with self.assertRaises(AlreadyBuiltError):
+            to.returns(None)
+        builder.build()
+        with self.assertRaises(AlreadyBuiltError):
+            builder.state("hello")
+        with self.assertRaises(AlreadyBuiltError):
+            builder.build()
+
+    def test_methodMembership(self) -> None:
+        """
+        Input methods must be members of their protocol.
+        """
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+        state = builder.state("test-state")
+
+        def stateful(proto: ProtocolForTesting, core: NoOpCore) -> int:
+            return 4  # pragma: no cover
+
+        state2 = builder.state("state2", stateful)
+
+        def change(self: ProtocolForTesting) -> None: ...
+
+        def rogue(self: ProtocolForTesting) -> int:
+            return 3  # pragma: no cover
+
+        with self.assertRaises(ValueError):
+            state.upon(change)
+        with self.assertRaises(ValueError) as ve:
+            state2.upon(change)
+        with self.assertRaises(ValueError):
+            state.upon(rogue)
+
+    def test_startInAlternateState(self) -> None:
+        """
+        The state machine can be started in an alternate state.
+        """
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+        one = builder.state("one")
+        two = builder.state("two")
+
+        @dataclass
+        class Three:
+            proto: ProtocolForTesting
+            core: NoOpCore
+            value: int = 0
+
+        three = builder.state("three", Three)
+        one.upon(ProtocolForTesting.change).to(two).returns(None)
+        one.upon(ProtocolForTesting.value).loop().returns(1)
+        two.upon(ProtocolForTesting.change).to(three).returns(None)
+        two.upon(ProtocolForTesting.value).loop().returns(2)
+
+        @pep614(three.upon(ProtocolForTesting.value).loop())
+        def threevalue(proto: ProtocolForTesting, core: NoOpCore, three: Three) -> int:
+            return 3 + three.value
+
+        onetwothree = builder.build()
+
+        # confirm positive behavior first, particularly the value of the three
+        # state's change
+        normal = onetwothree(NoOpCore())
+        self.assertEqual(normal.value(), 1)
+        normal.change()
+        self.assertEqual(normal.value(), 2)
+        normal.change()
+        self.assertEqual(normal.value(), 3)
+
+        # now try deserializing it in each state
+        self.assertEqual(onetwothree(NoOpCore()).value(), 1)
+        self.assertEqual(onetwothree(NoOpCore(), two).value(), 2)
+        self.assertEqual(
+            onetwothree(
+                NoOpCore(), three, lambda proto, core: Three(proto, core, 4)
+            ).value(),
+            7,
+        )
+
+    def test_genericData(self) -> None:
+        """
+        Test to cover get_origin in generic assertion.
+        """
+        builder = TypeMachineBuilder(ArgTaker, NoOpCore)
+        one = builder.state("one")
+
+        def dat(
+            proto: ArgTaker, core: NoOpCore, arg1: int = 0, arg2: str = ""
+        ) -> Gen[int]:
+            return Gen(arg1)
+
+        two = builder.state("two", dat)
+        one.upon(ArgTaker.takeSomeArgs).to(two).returns(None)
+
+        @pep614(two.upon(ArgTaker.value).loop())
+        def val(proto: ArgTaker, core: NoOpCore, data: Gen[int]) -> int:
+            return data.t
+
+        b = builder.build()
+        m = b(NoOpCore())
+        m.takeSomeArgs(3)
+        self.assertEqual(m.value(), 3)
+
+    @skipIf(not hasInterface, "zope.interface not installed")
+    def test_interfaceData(self) -> None:
+        """
+        Test to cover providedBy assertion.
+        """
+        builder = TypeMachineBuilder(ArgTaker, NoOpCore)
+        one = builder.state("one")
+
+        @implementer(ISomething)
+        @dataclass
+        class Something:
+            val: int
+
+            def something(self) -> int:
+                return self.val
+
+        def dat(
+            proto: ArgTaker, core: NoOpCore, arg1: int = 0, arg2: str = ""
+        ) -> ISomething:
+            return Something(arg1)  # type:ignore[return-value]
+
+        two = builder.state("two", dat)
+        one.upon(ArgTaker.takeSomeArgs).to(two).returns(None)
+
+        @pep614(two.upon(ArgTaker.value).loop())
+        def val(proto: ArgTaker, core: NoOpCore, data: ISomething) -> int:
+            return data.something()  # type:ignore[misc]
+
+        b = builder.build()
+        m = b(NoOpCore())
+        m.takeSomeArgs(3)
+        self.assertEqual(m.value(), 3)
+
+    def test_noMethodsInAltStateDataFactory(self) -> None:
+        """
+        When the state machine is received by a data factory during
+        construction, it is in an invalid state.  It may be invoked after
+        construction is complete.
+        """
+        builder = TypeMachineBuilder(ProtocolForTesting, NoOpCore)
+
+        @dataclass
+        class Data:
+            value: int
+            proto: ProtocolForTesting
+
+        start = builder.state("start")
+        data = builder.state("data", lambda proto, core: Data(3, proto))
+
+        @pep614(data.upon(ProtocolForTesting.value).loop())
+        def getval(proto: ProtocolForTesting, core: NoOpCore, data: Data) -> int:
+            return data.value
+
+        @pep614(start.upon(ProtocolForTesting.value).loop())
+        def minusone(proto: ProtocolForTesting, core: NoOpCore) -> int:
+            return -1
+
+        factory = builder.build()
+        self.assertEqual(factory(NoOpCore()).value(), -1)
+
+        def touchproto(proto: ProtocolForTesting, core: NoOpCore) -> Data:
+            return Data(proto.value(), proto)
+
+        catchdata = []
+
+        def notouchproto(proto: ProtocolForTesting, core: NoOpCore) -> Data:
+            catchdata.append(new := Data(4, proto))
+            return new
+
+        with self.assertRaises(NoTransition):
+            factory(NoOpCore(), data, touchproto)
+        machine = factory(NoOpCore(), data, notouchproto)
+        self.assertIs(machine, catchdata[0].proto)
+        self.assertEqual(machine.value(), 4)

.venv/lib/python3.12/site-packages/automat/_test/test_visualize.py

@@ -0,0 +1,478 @@
+from __future__ import annotations
+
+import functools
+import os
+import subprocess
+from dataclasses import dataclass
+from typing import Protocol
+from unittest import TestCase, skipIf
+
+from automat import TypeMachineBuilder, pep614
+
+from .._methodical import MethodicalMachine
+from .._typed import TypeMachine
+from .test_discover import isTwistedInstalled
+
+
+def isGraphvizModuleInstalled():
+    """
+    Is the graphviz Python module installed?
+    """
+    try:
+        __import__("graphviz")
+    except ImportError:
+        return False
+    else:
+        return True
+
+
+def isGraphvizInstalled():
+    """
+    Are the graphviz tools installed?
+    """
+    r, w = os.pipe()
+    os.close(w)
+    try:
+        return not subprocess.call("dot", stdin=r, shell=True)
+    finally:
+        os.close(r)
+
+
+def sampleMachine():
+    """
+    Create a sample L{MethodicalMachine} with some sample states.
+    """
+    mm = MethodicalMachine()
+
+    class SampleObject(object):
+        @mm.state(initial=True)
+        def begin(self):
+            "initial state"
+
+        @mm.state()
+        def end(self):
+            "end state"
+
+        @mm.input()
+        def go(self):
+            "sample input"
+
+        @mm.output()
+        def out(self):
+            "sample output"
+
+        begin.upon(go, end, [out])
+
+    so = SampleObject()
+    so.go()
+    return mm
+
+
+class Sample(Protocol):
+    def go(self) -> None: ...
+class Core: ...
+
+
+def sampleTypeMachine() -> TypeMachine[Sample, Core]:
+    """
+    Create a sample L{TypeMachine} with some sample states.
+    """
+    builder = TypeMachineBuilder(Sample, Core)
+    begin = builder.state("begin")
+
+    def buildit(proto: Sample, core: Core) -> int:
+        return 3  # pragma: no cover
+
+    data = builder.state("data", buildit)
+    end = builder.state("end")
+    begin.upon(Sample.go).to(data).returns(None)
+    data.upon(Sample.go).to(end).returns(None)
+
+    @pep614(end.upon(Sample.go).to(begin))
+    def out(sample: Sample, core: Core) -> None: ...
+
+    return builder.build()
+
+
+@skipIf(not isGraphvizModuleInstalled(), "Graphviz module is not installed.")
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class ElementMakerTests(TestCase):
+    """
+    L{elementMaker} generates HTML representing the specified element.
+    """
+
+    def setUp(self):
+        from .._visualize import elementMaker
+
+        self.elementMaker = elementMaker
+
+    def test_sortsAttrs(self):
+        """
+        L{elementMaker} orders HTML attributes lexicographically.
+        """
+        expected = r'<div a="1" b="2" c="3"></div>'
+        self.assertEqual(expected, self.elementMaker("div", b="2", a="1", c="3"))
+
+    def test_quotesAttrs(self):
+        """
+        L{elementMaker} quotes HTML attributes according to DOT's quoting rule.
+
+        See U{http://www.graphviz.org/doc/info/lang.html}, footnote 1.
+        """
+        expected = r'<div a="1" b="a \" quote" c="a string"></div>'
+        self.assertEqual(
+            expected, self.elementMaker("div", b='a " quote', a=1, c="a string")
+        )
+
+    def test_noAttrs(self):
+        """
+        L{elementMaker} should render an element with no attributes.
+        """
+        expected = r"<div ></div>"
+        self.assertEqual(expected, self.elementMaker("div"))
+
+
+@dataclass
+class HTMLElement(object):
+    """Holds an HTML element, as created by elementMaker."""
+
+    name: str
+    children: list[HTMLElement]
+    attributes: dict[str, str]
+
+
+def findElements(element, predicate):
+    """
+    Recursively collect all elements in an L{HTMLElement} tree that
+    match the optional predicate.
+    """
+    if predicate(element):
+        return [element]
+    elif isLeaf(element):
+        return []
+
+    return [
+        result
+        for child in element.children
+        for result in findElements(child, predicate)
+    ]
+
+
+def isLeaf(element):
+    """
+    This HTML element is actually leaf node.
+    """
+    return not isinstance(element, HTMLElement)
+
+
+@skipIf(not isGraphvizModuleInstalled(), "Graphviz module is not installed.")
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class TableMakerTests(TestCase):
+    """
+    Tests that ensure L{tableMaker} generates HTML tables usable as
+    labels in DOT graphs.
+
+    For more information, read the "HTML-Like Labels" section of
+    U{http://www.graphviz.org/doc/info/shapes.html}.
+    """
+
+    def fakeElementMaker(self, name, *children, **attributes):
+        return HTMLElement(name=name, children=children, attributes=attributes)
+
+    def setUp(self):
+        from .._visualize import tableMaker
+
+        self.inputLabel = "input label"
+        self.port = "the port"
+        self.tableMaker = functools.partial(tableMaker, _E=self.fakeElementMaker)
+
+    def test_inputLabelRow(self):
+        """
+        The table returned by L{tableMaker} always contains the input
+        symbol label in its first row, and that row contains one cell
+        with a port attribute set to the provided port.
+        """
+
+        def hasPort(element):
+            return not isLeaf(element) and element.attributes.get("port") == self.port
+
+        for outputLabels in ([], ["an output label"]):
+            table = self.tableMaker(self.inputLabel, outputLabels, port=self.port)
+            self.assertGreater(len(table.children), 0)
+            inputLabelRow = table.children[0]
+
+            portCandidates = findElements(table, hasPort)
+
+            self.assertEqual(len(portCandidates), 1)
+            self.assertEqual(portCandidates[0].name, "td")
+            self.assertEqual(findElements(inputLabelRow, isLeaf), [self.inputLabel])
+
+    def test_noOutputLabels(self):
+        """
+        L{tableMaker} does not add a colspan attribute to the input
+        label's cell or a second row if there no output labels.
+        """
+        table = self.tableMaker("input label", (), port=self.port)
+        self.assertEqual(len(table.children), 1)
+        (inputLabelRow,) = table.children
+        self.assertNotIn("colspan", inputLabelRow.attributes)
+
+    def test_withOutputLabels(self):
+        """
+        L{tableMaker} adds a colspan attribute to the input label's cell
+        equal to the number of output labels and a second row that
+        contains the output labels.
+        """
+        table = self.tableMaker(
+            self.inputLabel, ("output label 1", "output label 2"), port=self.port
+        )
+
+        self.assertEqual(len(table.children), 2)
+        inputRow, outputRow = table.children
+
+        def hasCorrectColspan(element):
+            return (
+                not isLeaf(element)
+                and element.name == "td"
+                and element.attributes.get("colspan") == "2"
+            )
+
+        self.assertEqual(len(findElements(inputRow, hasCorrectColspan)), 1)
+        self.assertEqual(
+            findElements(outputRow, isLeaf), ["output label 1", "output label 2"]
+        )
+
+
+@skipIf(not isGraphvizModuleInstalled(), "Graphviz module is not installed.")
+@skipIf(not isGraphvizInstalled(), "Graphviz tools are not installed.")
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class IntegrationTests(TestCase):
+    """
+    Tests which make sure Graphviz can understand the output produced by
+    Automat.
+    """
+
+    def test_validGraphviz(self) -> None:
+        """
+        C{graphviz} emits valid graphviz data.
+        """
+        digraph = sampleMachine().asDigraph()
+        text = "".join(digraph).encode("utf-8")
+        p = subprocess.Popen("dot", stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+        out, err = p.communicate(text)
+        self.assertEqual(p.returncode, 0)
+
+
+@skipIf(not isGraphvizModuleInstalled(), "Graphviz module is not installed.")
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class SpotChecks(TestCase):
+    """
+    Tests to make sure that the output contains salient features of the machine
+    being generated.
+    """
+
+    def test_containsMachineFeatures(self):
+        """
+        The output of L{graphviz.Digraph} should contain the names of the
+        states, inputs, outputs in the state machine.
+        """
+        gvout = "".join(sampleMachine().asDigraph())
+        self.assertIn("begin", gvout)
+        self.assertIn("end", gvout)
+        self.assertIn("go", gvout)
+        self.assertIn("out", gvout)
+
+    def test_containsTypeMachineFeatures(self):
+        """
+        The output of L{graphviz.Digraph} should contain the names of the states,
+        inputs, outputs in the state machine.
+        """
+        gvout = "".join(sampleTypeMachine().asDigraph())
+        self.assertIn("begin", gvout)
+        self.assertIn("end", gvout)
+        self.assertIn("go", gvout)
+        self.assertIn("data:buildit", gvout)
+        self.assertIn("out", gvout)
+
+
+class RecordsDigraphActions(object):
+    """
+    Records calls made to L{FakeDigraph}.
+    """
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.renderCalls = []
+        self.saveCalls = []
+
+
+class FakeDigraph(object):
+    """
+    A fake L{graphviz.Digraph}.  Instantiate it with a
+    L{RecordsDigraphActions}.
+    """
+
+    def __init__(self, recorder):
+        self._recorder = recorder
+
+    def render(self, **kwargs):
+        self._recorder.renderCalls.append(kwargs)
+
+    def save(self, **kwargs):
+        self._recorder.saveCalls.append(kwargs)
+
+
+class FakeMethodicalMachine(object):
+    """
+    A fake L{MethodicalMachine}.  Instantiate it with a L{FakeDigraph}
+    """
+
+    def __init__(self, digraph):
+        self._digraph = digraph
+
+    def asDigraph(self):
+        return self._digraph
+
+
+@skipIf(not isGraphvizModuleInstalled(), "Graphviz module is not installed.")
+@skipIf(not isGraphvizInstalled(), "Graphviz tools are not installed.")
+@skipIf(not isTwistedInstalled(), "Twisted is not installed.")
+class VisualizeToolTests(TestCase):
+    def setUp(self):
+        self.digraphRecorder = RecordsDigraphActions()
+        self.fakeDigraph = FakeDigraph(self.digraphRecorder)
+
+        self.fakeProgname = "tool-test"
+        self.fakeSysPath = ["ignored"]
+        self.collectedOutput = []
+        self.fakeFQPN = "fake.fqpn"
+
+    def collectPrints(self, *args):
+        self.collectedOutput.append(" ".join(args))
+
+    def fakeFindMachines(self, fqpn):
+        yield fqpn, FakeMethodicalMachine(self.fakeDigraph)
+
+    def tool(
+        self, progname=None, argv=None, syspath=None, findMachines=None, print=None
+    ):
+        from .._visualize import tool
+
+        return tool(
+            _progname=progname or self.fakeProgname,
+            _argv=argv or [self.fakeFQPN],
+            _syspath=syspath or self.fakeSysPath,
+            _findMachines=findMachines or self.fakeFindMachines,
+            _print=print or self.collectPrints,
+        )
+
+    def test_checksCurrentDirectory(self):
+        """
+        L{tool} adds '' to sys.path to ensure
+        L{automat._discover.findMachines} searches the current
+        directory.
+        """
+        self.tool(argv=[self.fakeFQPN])
+        self.assertEqual(self.fakeSysPath[0], "")
+
+    def test_quietHidesOutput(self):
+        """
+        Passing -q/--quiet hides all output.
+        """
+        self.tool(argv=[self.fakeFQPN, "--quiet"])
+        self.assertFalse(self.collectedOutput)
+        self.tool(argv=[self.fakeFQPN, "-q"])
+        self.assertFalse(self.collectedOutput)
+
+    def test_onlySaveDot(self):
+        """
+        Passing an empty string for --image-directory/-i disables
+        rendering images.
+        """
+        for arg in ("--image-directory", "-i"):
+            self.digraphRecorder.reset()
+            self.collectedOutput = []
+
+            self.tool(argv=[self.fakeFQPN, arg, ""])
+            self.assertFalse(any("image" in line for line in self.collectedOutput))
+
+            self.assertEqual(len(self.digraphRecorder.saveCalls), 1)
+            (call,) = self.digraphRecorder.saveCalls
+            self.assertEqual("{}.dot".format(self.fakeFQPN), call["filename"])
+
+            self.assertFalse(self.digraphRecorder.renderCalls)
+
+    def test_saveOnlyImage(self):
+        """
+        Passing an empty string for --dot-directory/-d disables saving dot
+        files.
+        """
+        for arg in ("--dot-directory", "-d"):
+            self.digraphRecorder.reset()
+            self.collectedOutput = []
+            self.tool(argv=[self.fakeFQPN, arg, ""])
+
+            self.assertFalse(any("dot" in line for line in self.collectedOutput))
+
+            self.assertEqual(len(self.digraphRecorder.renderCalls), 1)
+            (call,) = self.digraphRecorder.renderCalls
+            self.assertEqual("{}.dot".format(self.fakeFQPN), call["filename"])
+            self.assertTrue(call["cleanup"])
+
+            self.assertFalse(self.digraphRecorder.saveCalls)
+
+    def test_saveDotAndImagesInDifferentDirectories(self):
+        """
+        Passing different directories to --image-directory and --dot-directory
+        writes images and dot files to those directories.
+        """
+        imageDirectory = "image"
+        dotDirectory = "dot"
+        self.tool(
+            argv=[
+                self.fakeFQPN,
+                "--image-directory",
+                imageDirectory,
+                "--dot-directory",
+                dotDirectory,
+            ]
+        )
+
+        self.assertTrue(any("image" in line for line in self.collectedOutput))
+        self.assertTrue(any("dot" in line for line in self.collectedOutput))
+
+        self.assertEqual(len(self.digraphRecorder.renderCalls), 1)
+        (renderCall,) = self.digraphRecorder.renderCalls
+        self.assertEqual(renderCall["directory"], imageDirectory)
+        self.assertTrue(renderCall["cleanup"])
+
+        self.assertEqual(len(self.digraphRecorder.saveCalls), 1)
+        (saveCall,) = self.digraphRecorder.saveCalls
+        self.assertEqual(saveCall["directory"], dotDirectory)
+
+    def test_saveDotAndImagesInSameDirectory(self):
+        """
+        Passing the same directory to --image-directory and --dot-directory
+        writes images and dot files to that one directory.
+        """
+        directory = "imagesAndDot"
+        self.tool(
+            argv=[
+                self.fakeFQPN,
+                "--image-directory",
+                directory,
+                "--dot-directory",
+                directory,
+            ]
+        )
+
+        self.assertTrue(any("image and dot" in line for line in self.collectedOutput))
+
+        self.assertEqual(len(self.digraphRecorder.renderCalls), 1)
+        (renderCall,) = self.digraphRecorder.renderCalls
+        self.assertEqual(renderCall["directory"], directory)
+        self.assertFalse(renderCall["cleanup"])
+
+        self.assertFalse(len(self.digraphRecorder.saveCalls))

.venv/lib/python3.12/site-packages/automat/_typed.py

@@ -0,0 +1,736 @@
+# -*- test-case-name: automat._test.test_type_based -*-
+from __future__ import annotations
+
+import sys
+from dataclasses import dataclass, field
+from typing import (
+    TYPE_CHECKING,
+    get_origin,
+    Any,
+    Callable,
+    Generic,
+    Iterable,
+    Literal,
+    Protocol,
+    TypeVar,
+    overload,
+)
+
+if TYPE_CHECKING:
+    from graphviz import Digraph
+try:
+    from zope.interface.interface import InterfaceClass  # type:ignore[import-untyped]
+except ImportError:
+    hasInterface = False
+else:
+    hasInterface = True
+
+if sys.version_info < (3, 10):
+    from typing_extensions import Concatenate, ParamSpec, TypeAlias
+else:
+    from typing import Concatenate, ParamSpec, TypeAlias
+
+from ._core import Automaton, Transitioner
+from ._runtimeproto import (
+    ProtocolAtRuntime,
+    _liveSignature,
+    actuallyDefinedProtocolMethods,
+    runtime_name,
+)
+
+
+class AlreadyBuiltError(Exception):
+    """
+    The L{TypeMachine} is already built, and thus can no longer be
+    modified.
+    """
+
+
+InputProtocol = TypeVar("InputProtocol")
+Core = TypeVar("Core")
+Data = TypeVar("Data")
+P = ParamSpec("P")
+P1 = ParamSpec("P1")
+R = TypeVar("R")
+OtherData = TypeVar("OtherData")
+Decorator = Callable[[Callable[P, R]], Callable[P, R]]
+FactoryParams = ParamSpec("FactoryParams")
+OtherFactoryParams = ParamSpec("OtherFactoryParams")
+
+
+def pep614(t: R) -> R:
+    """
+    This is a workaround for Python 3.8, which has U{some restrictions on its
+    grammar for decorators <https://peps.python.org/pep-0614/>}, and makes
+    C{@state.to(other).upon(Protocol.input)} invalid syntax; for code that
+    needs to run on these older Python versions, you can do
+    C{@pep614(state.to(other).upon(Protocol.input))} instead.
+    """
+    return t
+
+
+@dataclass()
+class TransitionRegistrar(Generic[P, P1, R]):
+    """
+    This is a record of a transition that need finalizing; it is the result of
+    calling L{TypeMachineBuilder.state} and then ``.upon(input).to(state)`` on
+    the result of that.
+
+    It can be used as a decorator, like::
+
+        registrar = state.upon(Proto.input).to(state2)
+        @registrar
+        def inputImplementation(proto: Proto, core: Core) -> Result: ...
+
+    Or, it can be used used to implement a constant return value with
+    L{TransitionRegistrar.returns}, like::
+
+        registrar = state.upon(Proto.input).to(state2)
+        registrar.returns(value)
+
+    Type parameter P: the precise signature of the decorated implementation
+    callable.
+
+    Type parameter P1: the precise signature of the input method from the
+    outward-facing state-machine protocol.
+
+    Type parameter R: the return type of both the protocol method and the input
+    method.
+    """
+
+    _signature: Callable[P1, R]
+    _old: AnyState
+    _new: AnyState
+    _nodata: bool = False
+    _callback: Callable[P, R] | None = None
+
+    def __post_init__(self) -> None:
+        self._old.builder._registrars.append(self)
+
+    def __call__(self, impl: Callable[P, R]) -> Callable[P, R]:
+        """
+        Finalize it with C{__call__} to indicate that there is an
+        implementation to the transition, which can be treated as an output.
+        """
+        if self._callback is not None:
+            raise AlreadyBuiltError(
+                f"already registered transition from {self._old.name!r} to {self._new.name!r}"
+            )
+        self._callback = impl
+        builder = self._old.builder
+        assert builder is self._new.builder, "states must be from the same builder"
+        builder._automaton.addTransition(
+            self._old,
+            self._signature.__name__,
+            self._new,
+            tuple(self._new._produceOutputs(impl, self._old, self._nodata)),
+        )
+        return impl
+
+    def returns(self, result: R) -> None:
+        """
+        Finalize it with C{.returns(constant)} to indicate that there is no
+        method body, and the given result can just be yielded each time after
+        the state transition.  The only output generated in this case would be
+        the data-construction factory for the target state.
+        """
+
+        def constant(*args: object, **kwargs: object) -> R:
+            return result
+
+        constant.__name__ = f"returns({result})"
+        self(constant)
+
+    def _checkComplete(self) -> None:
+        """
+        Raise an exception if the user forgot to decorate a method
+        implementation or supply a return value for this transition.
+        """
+        # TODO: point at the line where `.to`/`.loop`/`.upon` are called so the
+        # user can more immediately see the incomplete transition
+        if not self._callback:
+            raise ValueError(
+                f"incomplete transition from {self._old.name} to "
+                f"{self._new.name} upon {self._signature.__qualname__}: "
+                "remember to use the transition as a decorator or call "
+                "`.returns` on it."
+            )
+
+
+@dataclass
+class UponFromNo(Generic[InputProtocol, Core, P, R]):
+    """
+    Type parameter P: the signature of the input method.
+    """
+
+    old: TypedState[InputProtocol, Core] | TypedDataState[InputProtocol, Core, Any, ...]
+    input: Callable[Concatenate[InputProtocol, P], R]
+
+    @overload
+    def to(
+        self, state: TypedState[InputProtocol, Core]
+    ) -> TransitionRegistrar[Concatenate[InputProtocol, Core, P], P, R]: ...
+    @overload
+    def to(
+        self,
+        state: TypedDataState[InputProtocol, Core, OtherData, P],
+    ) -> TransitionRegistrar[
+        Concatenate[InputProtocol, Core, P],
+        Concatenate[InputProtocol, P],
+        R,
+    ]: ...
+    def to(
+        self,
+        state: (
+            TypedState[InputProtocol, Core]
+            | TypedDataState[InputProtocol, Core, Any, P]
+        ),
+    ) -> (
+        TransitionRegistrar[Concatenate[InputProtocol, Core, P], P, R]
+        | TransitionRegistrar[
+            Concatenate[InputProtocol, Core, P],
+            Concatenate[InputProtocol, P],
+            R,
+        ]
+    ):
+        """
+        Declare a state transition to a new state.
+        """
+        return TransitionRegistrar(self.input, self.old, state, True)
+
+    def loop(self) -> TransitionRegistrar[
+        Concatenate[InputProtocol, Core, P],
+        Concatenate[InputProtocol, P],
+        R,
+    ]:
+        """
+        Register a transition back to the same state.
+        """
+        return TransitionRegistrar(self.input, self.old, self.old, True)
+
+
+@dataclass
+class UponFromData(Generic[InputProtocol, Core, P, R, Data]):
+    """
+    Type parameter P: the signature of the input method.
+    """
+
+    old: TypedDataState[InputProtocol, Core, Data, ...]
+    input: Callable[Concatenate[InputProtocol, P], R]
+
+    @overload
+    def to(
+        self, state: TypedState[InputProtocol, Core]
+    ) -> TransitionRegistrar[
+        Concatenate[InputProtocol, Core, Data, P], Concatenate[InputProtocol, P], R
+    ]: ...
+    @overload
+    def to(
+        self,
+        state: TypedDataState[InputProtocol, Core, OtherData, P],
+    ) -> TransitionRegistrar[
+        Concatenate[InputProtocol, Core, Data, P],
+        Concatenate[InputProtocol, P],
+        R,
+    ]: ...
+    def to(
+        self,
+        state: (
+            TypedState[InputProtocol, Core]
+            | TypedDataState[InputProtocol, Core, Any, P]
+        ),
+    ) -> (
+        TransitionRegistrar[Concatenate[InputProtocol, Core, P], P, R]
+        | TransitionRegistrar[
+            Concatenate[InputProtocol, Core, Data, P],
+            Concatenate[InputProtocol, P],
+            R,
+        ]
+    ):
+        """
+        Declare a state transition to a new state.
+        """
+        return TransitionRegistrar(self.input, self.old, state)
+
+    def loop(self) -> TransitionRegistrar[
+        Concatenate[InputProtocol, Core, Data, P],
+        Concatenate[InputProtocol, P],
+        R,
+    ]:
+        """
+        Register a transition back to the same state.
+        """
+        return TransitionRegistrar(self.input, self.old, self.old)
+
+
+@dataclass(frozen=True)
+class TypedState(Generic[InputProtocol, Core]):
+    """
+    The result of L{.state() <automat.TypeMachineBuilder.state>}.
+    """
+
+    name: str
+    builder: TypeMachineBuilder[InputProtocol, Core] = field(repr=False)
+
+    def upon(
+        self, input: Callable[Concatenate[InputProtocol, P], R]
+    ) -> UponFromNo[InputProtocol, Core, P, R]:
+        ".upon()"
+        self.builder._checkMembership(input)
+        return UponFromNo(self, input)
+
+    def _produceOutputs(
+        self,
+        impl: Callable[..., object],
+        old: (
+            TypedDataState[InputProtocol, Core, OtherData, OtherFactoryParams]
+            | TypedState[InputProtocol, Core]
+        ),
+        nodata: bool = False,
+    ) -> Iterable[SomeOutput]:
+        yield MethodOutput._fromImpl(impl, isinstance(old, TypedDataState))
+
+
+@dataclass(frozen=True)
+class TypedDataState(Generic[InputProtocol, Core, Data, FactoryParams]):
+    name: str
+    builder: TypeMachineBuilder[InputProtocol, Core] = field(repr=False)
+    factory: Callable[Concatenate[InputProtocol, Core, FactoryParams], Data]
+
+    @overload
+    def upon(
+        self, input: Callable[Concatenate[InputProtocol, P], R]
+    ) -> UponFromData[InputProtocol, Core, P, R, Data]: ...
+    @overload
+    def upon(
+        self, input: Callable[Concatenate[InputProtocol, P], R], nodata: Literal[False]
+    ) -> UponFromData[InputProtocol, Core, P, R, Data]: ...
+    @overload
+    def upon(
+        self, input: Callable[Concatenate[InputProtocol, P], R], nodata: Literal[True]
+    ) -> UponFromNo[InputProtocol, Core, P, R]: ...
+    def upon(
+        self,
+        input: Callable[Concatenate[InputProtocol, P], R],
+        nodata: bool = False,
+    ) -> (
+        UponFromData[InputProtocol, Core, P, R, Data]
+        | UponFromNo[InputProtocol, Core, P, R]
+    ):
+        self.builder._checkMembership(input)
+        if nodata:
+            return UponFromNo(self, input)
+        else:
+            return UponFromData(self, input)
+
+    def _produceOutputs(
+        self,
+        impl: Callable[..., object],
+        old: (
+            TypedDataState[InputProtocol, Core, OtherData, OtherFactoryParams]
+            | TypedState[InputProtocol, Core]
+        ),
+        nodata: bool,
+    ) -> Iterable[SomeOutput]:
+        if self is not old:
+            yield DataOutput(self.factory)
+        yield MethodOutput._fromImpl(
+            impl, isinstance(old, TypedDataState) and not nodata
+        )
+
+
+AnyState: TypeAlias = "TypedState[Any, Any] | TypedDataState[Any, Any, Any, Any]"
+
+
+@dataclass
+class TypedInput:
+    name: str
+
+
+class SomeOutput(Protocol):
+    """
+    A state machine output.
+    """
+
+    @property
+    def name(self) -> str:
+        "read-only name property"
+
+    def __call__(*args: Any, **kwargs: Any) -> Any: ...
+
+    def __hash__(self) -> int:
+        "must be hashable"
+
+
+@dataclass
+class InputImplementer(Generic[InputProtocol, Core]):
+    """
+    An L{InputImplementer} implements an input protocol in terms of a
+    state machine.
+
+    When the factory returned from L{TypeMachine}
+    """
+
+    __automat_core__: Core
+    __automat_transitioner__: Transitioner[
+        TypedState[InputProtocol, Core]
+        | TypedDataState[InputProtocol, Core, object, ...],
+        str,
+        SomeOutput,
+    ]
+    __automat_data__: object | None = None
+    __automat_postponed__: list[Callable[[], None]] | None = None
+
+
+def implementMethod(
+    method: Callable[..., object],
+) -> Callable[..., object]:
+    """
+    Construct a function for populating in the synthetic provider of the Input
+    Protocol to a L{TypeMachineBuilder}.  It should have a signature matching that
+    of the C{method} parameter, a function from that protocol.
+    """
+    methodInput = method.__name__
+    # side-effects can be re-ordered until later.  If you need to compute a
+    # value in your method, then obviously it can't be invoked reentrantly.
+    returnAnnotation = _liveSignature(method).return_annotation
+    returnsNone = returnAnnotation is None
+
+    def implementation(
+        self: InputImplementer[InputProtocol, Core], *args: object, **kwargs: object
+    ) -> object:
+        transitioner = self.__automat_transitioner__
+        dataAtStart = self.__automat_data__
+        if self.__automat_postponed__ is not None:
+            if not returnsNone:
+                raise RuntimeError(
+                    f"attempting to reentrantly run {method.__qualname__} "
+                    f"but it wants to return {returnAnnotation!r} not None"
+                )
+
+            def rerunme() -> None:
+                implementation(self, *args, **kwargs)
+
+            self.__automat_postponed__.append(rerunme)
+            return None
+        postponed = self.__automat_postponed__ = []
+        try:
+            [outputs, tracer] = transitioner.transition(methodInput)
+            result: Any = None
+            for output in outputs:
+                # here's the idea: there will be a state-setup output and a
+                # state-teardown output. state-setup outputs are added to the
+                # *beginning* of any entry into a state, so that by the time you
+                # are running the *implementation* of a method that has entered
+                # that state, the protocol is in a self-consistent state and can
+                # run reentrant outputs.  not clear that state-teardown outputs are
+                # necessary
+                result = output(self, dataAtStart, *args, **kwargs)
+        finally:
+            self.__automat_postponed__ = None
+        while postponed:
+            postponed.pop(0)()
+        return result
+
+    implementation.__qualname__ = implementation.__name__ = (
+        f"<implementation for {method}>"
+    )
+    return implementation
+
+
+@dataclass(frozen=True)
+class MethodOutput(Generic[Core]):
+    """
+    This is the thing that goes into the automaton's outputs list, and thus
+    (per the implementation of L{implementMethod}) takes the 'self' of the
+    InputImplementer instance (i.e. the synthetic protocol implementation) and the
+    previous result computed by the former output, which will be None
+    initially.
+    """
+
+    method: Callable[..., Any]
+    requiresData: bool
+    _assertion: Callable[[object], None]
+
+    @classmethod
+    def _fromImpl(
+        cls: type[MethodOutput[Core]], method: Callable[..., Any], requiresData: bool
+    ) -> MethodOutput[Core]:
+        parameter = None
+        annotation: type[object] = object
+
+        def assertion(data: object) -> None:
+            """
+            No assertion about the data.
+            """
+
+        # Do our best to compute the declared signature, so that we caan verify
+        # it's the right type.  We can't always do that.
+        try:
+            sig = _liveSignature(method)
+        except NameError:
+            ...
+            # An inner function may refer to type aliases that only appear as
+            # local variables, and those are just lost here; give up.
+        else:
+            if requiresData:
+                # 0: self, 1: self.__automat_core__, 2: self.__automat_data__
+                declaredParams = list(sig.parameters.values())
+                if len(declaredParams) >= 3:
+                    parameter = declaredParams[2]
+                    annotation = parameter.annotation
+                    origin = get_origin(annotation)
+                    if origin is not None:
+                        annotation = origin
+                    if hasInterface and isinstance(annotation, InterfaceClass):
+
+                        def assertion(data: object) -> None:
+                            assert annotation.providedBy(data), (
+                                f"expected {parameter} to provide {annotation} "
+                                f"but got {type(data)} instead"
+                            )
+
+                    else:
+
+                        def assertion(data: object) -> None:
+                            assert isinstance(data, annotation), (
+                                f"expected {parameter} to be {annotation} "
+                                f"but got {type(data)} instead"
+                            )
+
+        return cls(method, requiresData, assertion)
+
+    @property
+    def name(self) -> str:
+        return f"{self.method.__name__}"
+
+    def __call__(
+        self,
+        machine: InputImplementer[InputProtocol, Core],
+        dataAtStart: Data,
+        /,
+        *args: object,
+        **kwargs: object,
+    ) -> object:
+        extraArgs = [machine, machine.__automat_core__]
+        if self.requiresData:
+            self._assertion(dataAtStart)
+            extraArgs += [dataAtStart]
+        # if anything is invoked reentrantly here, then we can't possibly have
+        # set __automat_data__ and the data argument to the reentrant method
+        # will be wrong.  we *need* to split out the construction / state-enter
+        # hook, because it needs to run separately.
+        return self.method(*extraArgs, *args, **kwargs)
+
+
+@dataclass(frozen=True)
+class DataOutput(Generic[Data]):
+    """
+    Construct an output for the given data objects.
+    """
+
+    dataFactory: Callable[..., Data]
+
+    @property
+    def name(self) -> str:
+        return f"data:{self.dataFactory.__name__}"
+
+    def __call__(
+        realself,
+        self: InputImplementer[InputProtocol, Core],
+        dataAtStart: object,
+        *args: object,
+        **kwargs: object,
+    ) -> Data:
+        newData = realself.dataFactory(self, self.__automat_core__, *args, **kwargs)
+        self.__automat_data__ = newData
+        return newData
+
+
+INVALID_WHILE_DESERIALIZING: TypedState[Any, Any] = TypedState(
+    "automat:invalid-while-deserializing",
+    None,  # type:ignore[arg-type]
+)
+
+
+@dataclass(frozen=True)
+class TypeMachine(Generic[InputProtocol, Core]):
+    """
+    A L{TypeMachine} is a factory for instances of C{InputProtocol}.
+    """
+
+    __automat_type__: type[InputImplementer[InputProtocol, Core]]
+    __automat_automaton__: Automaton[
+        TypedState[InputProtocol, Core] | TypedDataState[InputProtocol, Core, Any, ...],
+        str,
+        SomeOutput,
+    ]
+
+    @overload
+    def __call__(self, core: Core) -> InputProtocol: ...
+    @overload
+    def __call__(
+        self, core: Core, state: TypedState[InputProtocol, Core]
+    ) -> InputProtocol: ...
+    @overload
+    def __call__(
+        self,
+        core: Core,
+        state: TypedDataState[InputProtocol, Core, OtherData, ...],
+        dataFactory: Callable[[InputProtocol, Core], OtherData],
+    ) -> InputProtocol: ...
+
+    def __call__(
+        self,
+        core: Core,
+        state: (
+            TypedState[InputProtocol, Core]
+            | TypedDataState[InputProtocol, Core, OtherData, ...]
+            | None
+        ) = None,
+        dataFactory: Callable[[InputProtocol, Core], OtherData] | None = None,
+    ) -> InputProtocol:
+        """
+        Construct an instance of C{InputProtocol} from an instance of the
+        C{Core} protocol.
+        """
+        if state is None:
+            state = initial = self.__automat_automaton__.initialState
+        elif isinstance(state, TypedDataState):
+            assert dataFactory is not None, "data state requires a data factory"
+            # Ensure that the machine is in a state with *no* transitions while
+            # we are doing the initial construction of its state-specific data.
+            initial = INVALID_WHILE_DESERIALIZING
+        else:
+            initial = state
+
+        internals: InputImplementer[InputProtocol, Core] = self.__automat_type__(
+            core, txnr := Transitioner(self.__automat_automaton__, initial)
+        )
+        result: InputProtocol = internals  # type:ignore[assignment]
+
+        if dataFactory is not None:
+            internals.__automat_data__ = dataFactory(result, core)
+            txnr._state = state
+        return result
+
+    def asDigraph(self) -> Digraph:
+        from ._visualize import makeDigraph
+
+        return makeDigraph(
+            self.__automat_automaton__,
+            stateAsString=lambda state: state.name,
+            inputAsString=lambda input: input,
+            outputAsString=lambda output: output.name,
+        )
+
+
+@dataclass(eq=False)
+class TypeMachineBuilder(Generic[InputProtocol, Core]):
+    """
+    The main entry-point into Automat, used to construct a factory for
+    instances of C{InputProtocol} that take an instance of C{Core}.
+
+    Describe the machine with L{TypeMachineBuilder.state} L{.upon
+    <automat._typed.TypedState.upon>} L{.to
+    <automat._typed.UponFromNo.to>}, then build it with
+    L{TypeMachineBuilder.build}, like so::
+
+        from typing import Protocol
+        class Inputs(Protocol):
+            def method(self) -> None: ...
+        class Core: ...
+
+        from automat import TypeMachineBuilder
+        builder = TypeMachineBuilder(Inputs, Core)
+        state = builder.state("state")
+        state.upon(Inputs.method).loop().returns(None)
+        Machine = builder.build()
+
+        machine = Machine(Core())
+        machine.method()
+    """
+
+    # Public constructor parameters.
+    inputProtocol: ProtocolAtRuntime[InputProtocol]
+    coreType: type[Core]
+
+    # Internal state, not in the constructor.
+    _automaton: Automaton[
+        TypedState[InputProtocol, Core] | TypedDataState[InputProtocol, Core, Any, ...],
+        str,
+        SomeOutput,
+    ] = field(default_factory=Automaton, repr=False, init=False)
+    _initial: bool = field(default=True, init=False)
+    _registrars: list[TransitionRegistrar[..., ..., Any]] = field(
+        default_factory=list, init=False
+    )
+    _built: bool = field(default=False, init=False)
+
+    @overload
+    def state(self, name: str) -> TypedState[InputProtocol, Core]: ...
+    @overload
+    def state(
+        self,
+        name: str,
+        dataFactory: Callable[Concatenate[InputProtocol, Core, P], Data],
+    ) -> TypedDataState[InputProtocol, Core, Data, P]: ...
+    def state(
+        self,
+        name: str,
+        dataFactory: Callable[Concatenate[InputProtocol, Core, P], Data] | None = None,
+    ) -> TypedState[InputProtocol, Core] | TypedDataState[InputProtocol, Core, Data, P]:
+        """
+        Construct a state.
+        """
+        if self._built:
+            raise AlreadyBuiltError(
+                "Cannot add states to an already-built state machine."
+            )
+        if dataFactory is None:
+            state = TypedState(name, self)
+            if self._initial:
+                self._initial = False
+                self._automaton.initialState = state
+            return state
+        else:
+            assert not self._initial, "initial state cannot require state-specific data"
+            return TypedDataState(name, self, dataFactory)
+
+    def build(self) -> TypeMachine[InputProtocol, Core]:
+        """
+        Create a L{TypeMachine}, and prevent further modification to the state
+        machine being built.
+        """
+        # incompleteness check
+        if self._built:
+            raise AlreadyBuiltError("Cannot build a state machine twice.")
+        self._built = True
+
+        for registrar in self._registrars:
+            registrar._checkComplete()
+
+        # We were only hanging on to these for error-checking purposes, so we
+        # can drop them now.
+        del self._registrars[:]
+
+        runtimeType: type[InputImplementer[InputProtocol, Core]] = type(
+            f"Typed<{runtime_name(self.inputProtocol)}>",
+            tuple([InputImplementer]),
+            {
+                method_name: implementMethod(getattr(self.inputProtocol, method_name))
+                for method_name in actuallyDefinedProtocolMethods(self.inputProtocol)
+            },
+        )
+
+        return TypeMachine(runtimeType, self._automaton)
+
+    def _checkMembership(self, input: Callable[..., object]) -> None:
+        """
+        Ensure that ``input`` is a valid member function of the input protocol,
+        not just a function that happens to take the right first argument.
+        """
+        if (checked := getattr(self.inputProtocol, input.__name__, None)) is not input:
+            raise ValueError(
+                f"{input.__qualname__} is not a member of {self.inputProtocol.__module__}.{self.inputProtocol.__name__}"
+            )

.venv/lib/python3.12/site-packages/automat/_visualize.py

@@ -0,0 +1,230 @@
+from __future__ import annotations
+
+import argparse
+import sys
+from functools import wraps
+from typing import Callable, Iterator
+
+import graphviz
+
+from ._core import Automaton, Input, Output, State
+from ._discover import findMachines
+from ._methodical import MethodicalMachine
+from ._typed import TypeMachine, InputProtocol, Core
+
+
+def _gvquote(s: str) -> str:
+    return '"{}"'.format(s.replace('"', r"\""))
+
+
+def _gvhtml(s: str) -> str:
+    return "<{}>".format(s)
+
+
+def elementMaker(name: str, *children: str, **attrs: str) -> str:
+    """
+    Construct a string from the HTML element description.
+    """
+    formattedAttrs = " ".join(
+        "{}={}".format(key, _gvquote(str(value)))
+        for key, value in sorted(attrs.items())
+    )
+    formattedChildren = "".join(children)
+    return "<{name} {attrs}>{children}</{name}>".format(
+        name=name, attrs=formattedAttrs, children=formattedChildren
+    )
+
+
+def tableMaker(
+    inputLabel: str,
+    outputLabels: list[str],
+    port: str,
+    _E: Callable[..., str] = elementMaker,
+) -> str:
+    """
+    Construct an HTML table to label a state transition.
+    """
+    colspan = {}
+    if outputLabels:
+        colspan["colspan"] = str(len(outputLabels))
+
+    inputLabelCell = _E(
+        "td",
+        _E("font", inputLabel, face="menlo-italic"),
+        color="purple",
+        port=port,
+        **colspan,
+    )
+
+    pointSize = {"point-size": "9"}
+    outputLabelCells = [
+        _E("td", _E("font", outputLabel, **pointSize), color="pink")
+        for outputLabel in outputLabels
+    ]
+
+    rows = [_E("tr", inputLabelCell)]
+
+    if outputLabels:
+        rows.append(_E("tr", *outputLabelCells))
+
+    return _E("table", *rows)
+
+
+def escapify(x: Callable[[State], str]) -> Callable[[State], str]:
+    @wraps(x)
+    def impl(t: State) -> str:
+        return x(t).replace("<", "&lt;").replace(">", "&gt;")
+
+    return impl
+
+
+def makeDigraph(
+    automaton: Automaton[State, Input, Output],
+    inputAsString: Callable[[Input], str] = repr,
+    outputAsString: Callable[[Output], str] = repr,
+    stateAsString: Callable[[State], str] = repr,
+) -> graphviz.Digraph:
+    """
+    Produce a L{graphviz.Digraph} object from an automaton.
+    """
+
+    inputAsString = escapify(inputAsString)
+    outputAsString = escapify(outputAsString)
+    stateAsString = escapify(stateAsString)
+
+    digraph = graphviz.Digraph(
+        graph_attr={"pack": "true", "dpi": "100"},
+        node_attr={"fontname": "Menlo"},
+        edge_attr={"fontname": "Menlo"},
+    )
+
+    for state in automaton.states():
+        if state is automaton.initialState:
+            stateShape = "bold"
+            fontName = "Menlo-Bold"
+        else:
+            stateShape = ""
+            fontName = "Menlo"
+        digraph.node(
+            stateAsString(state),
+            fontame=fontName,
+            shape="ellipse",
+            style=stateShape,
+            color="blue",
+        )
+    for n, eachTransition in enumerate(automaton.allTransitions()):
+        inState, inputSymbol, outState, outputSymbols = eachTransition
+        thisTransition = "t{}".format(n)
+        inputLabel = inputAsString(inputSymbol)
+
+        port = "tableport"
+        table = tableMaker(
+            inputLabel,
+            [outputAsString(outputSymbol) for outputSymbol in outputSymbols],
+            port=port,
+        )
+
+        digraph.node(thisTransition, label=_gvhtml(table), margin="0.2", shape="none")
+
+        digraph.edge(
+            stateAsString(inState),
+            "{}:{}:w".format(thisTransition, port),
+            arrowhead="none",
+        )
+        digraph.edge("{}:{}:e".format(thisTransition, port), stateAsString(outState))
+
+    return digraph
+
+
+def tool(
+    _progname: str = sys.argv[0],
+    _argv: list[str] = sys.argv[1:],
+    _syspath: list[str] = sys.path,
+    _findMachines: Callable[
+        [str],
+        Iterator[tuple[str, MethodicalMachine | TypeMachine[InputProtocol, Core]]],
+    ] = findMachines,
+    _print: Callable[..., None] = print,
+) -> None:
+    """
+    Entry point for command line utility.
+    """
+
+    DESCRIPTION = """
+    Visualize automat.MethodicalMachines as graphviz graphs.
+    """
+    EPILOG = """
+    You must have the graphviz tool suite installed.  Please visit
+    http://www.graphviz.org for more information.
+    """
+    if _syspath[0]:
+        _syspath.insert(0, "")
+    argumentParser = argparse.ArgumentParser(
+        prog=_progname, description=DESCRIPTION, epilog=EPILOG
+    )
+    argumentParser.add_argument(
+        "fqpn",
+        help="A Fully Qualified Path name" " representing where to find machines.",
+    )
+    argumentParser.add_argument(
+        "--quiet", "-q", help="suppress output", default=False, action="store_true"
+    )
+    argumentParser.add_argument(
+        "--dot-directory",
+        "-d",
+        help="Where to write out .dot files.",
+        default=".automat_visualize",
+    )
+    argumentParser.add_argument(
+        "--image-directory",
+        "-i",
+        help="Where to write out image files.",
+        default=".automat_visualize",
+    )
+    argumentParser.add_argument(
+        "--image-type",
+        "-t",
+        help="The image format.",
+        choices=graphviz.FORMATS,
+        default="png",
+    )
+    argumentParser.add_argument(
+        "--view",
+        "-v",
+        help="View rendered graphs with" " default image viewer",
+        default=False,
+        action="store_true",
+    )
+    args = argumentParser.parse_args(_argv)
+
+    explicitlySaveDot = args.dot_directory and (
+        not args.image_directory or args.image_directory != args.dot_directory
+    )
+    if args.quiet:
+
+        def _print(*args):
+            pass
+
+    for fqpn, machine in _findMachines(args.fqpn):
+        _print(fqpn, "...discovered")
+
+        digraph = machine.asDigraph()
+
+        if explicitlySaveDot:
+            digraph.save(filename="{}.dot".format(fqpn), directory=args.dot_directory)
+            _print(fqpn, "...wrote dot into", args.dot_directory)
+
+        if args.image_directory:
+            deleteDot = not args.dot_directory or explicitlySaveDot
+            digraph.format = args.image_type
+            digraph.render(
+                filename="{}.dot".format(fqpn),
+                directory=args.image_directory,
+                view=args.view,
+                cleanup=deleteDot,
+            )
+            if deleteDot:
+                msg = "...wrote image into"
+            else:
+                msg = "...wrote image and dot into"
+            _print(fqpn, msg, args.image_directory)