Apply code styles via pre-commit

- Add black and isort for Python styling
- Add doc8 for reStructuredText styling
- Add prettier for css/html/js/md/yaml styling
- Run all styling tools from pre-commit hooks
- Adjust flake8 config for compatibility with black
  (and current Django style)
- Add some other helpful pre-commit hooks
- Update editorconfig to match Django
  (with a few necessary adjustments for Anymail)
- Update `tox -e lint` to run all pre-commit hooks
- Update contributing docs

.editorconfig

@@ -1,25 +1,55 @@
-# https://editorconfig.org
+# https://editorconfig.org/
+# This is adapted from Django's .editorconfig:
+# https://github.com/django/django/blob/main/.editorconfig
 
 root = true
 
 [*]
-charset = utf-8
-end_of_line = lf
-indent_size = 2
 indent_style = space
-insert_final_newline = true
-trim_trailing_whitespace = true
-
-[*.py]
 indent_size = 4
+insert_final_newline = true
+max_line_length = 88
+trim_trailing_whitespace = true
+end_of_line = lf
+charset = utf-8
+
+# Match pyproject.toml [tool.black] config:
+[*.py]
+max_line_length = 88
+
+# Match pyproject.toml [tool.doc8] config:
+[*.rst]
 max_line_length = 120
 
-[*.{ini,lock}]
+[*.md]
-indent_size = 4
+indent_size = 2
 
-[{Makefile,*.bat}]
+[*.html]
+indent_size = 2
+
+# Anymail uses smaller indents than Django in css and js sources
+[*.css]
+indent_size = 2
+
+[*.js]
+indent_size = 2
+
+[*.json]
+indent_size = 2
+
+# Minified files shouldn't be changed
+[**.min.{css,js}]
+indent_style = ignore
+insert_final_newline = ignore
+
+# Makefiles always use tabs for indentation
+[Makefile]
 indent_style = tab
-indent_size = 4
 
+# Batch files use tabs for indentation
 [*.bat]
 end_of_line = crlf
+indent_style = tab
+
+[*.{yml,yaml}]
+indent_size = 2

.flake8

@@ -1,2 +1,11 @@
 [flake8]
-max-line-length = 120
+extend-exclude =
+    build,
+    tests/test_settings/settings_*.py
+
+# Black compatibility:
+# - E203 (spaces around slice operators) is not PEP-8 compliant (and Black _is_)
+# - Black sometimes deliberately overruns max-line-length by a small amount
+#   (97 is Black's max-line-length of 88 + 10%)
+extend-ignore = E203
+max-line-length = 97

.pre-commit-config.yaml

@@ -0,0 +1,52 @@
+repos:
+  - repo: https://github.com/psf/black
+    rev: 23.1.0
+    hooks:
+      - id: black
+  - repo: https://github.com/pycqa/isort
+    rev: 5.12.0
+    hooks:
+      - id: isort
+  - repo: https://github.com/pycqa/flake8
+    rev: 6.0.0
+    hooks:
+      - id: flake8
+  - repo: https://github.com/pycqa/doc8
+    rev: v1.1.1
+    hooks:
+      - id: doc8
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    # rev: see
+    #   https://github.com/pre-commit/mirrors-prettier/issues/29#issuecomment-1332667344
+    rev: v2.7.1
+    hooks:
+      - id: prettier
+        files: '\.(css|html|jsx?|md|tsx?|ya?ml)$'
+        additional_dependencies:
+          - prettier@2.8.3
+  - repo: https://github.com/pre-commit/pygrep-hooks
+    rev: v1.10.0
+    hooks:
+      - id: python-check-blanket-noqa
+      - id: python-check-blanket-type-ignore
+      - id: python-no-eval
+      - id: python-no-log-warn
+      - id: python-use-type-annotations
+      # - id: rst-backticks
+      #   (no: some docs source uses single backticks expecting Sphinx default_role)
+      - id: rst-directive-colons
+      - id: rst-inline-touching-normal
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.4.0
+    hooks:
+      - id: check-json
+      - id: check-toml
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: fix-byte-order-marker
+      - id: fix-encoding-pragma
+        args: [--remove]
+      - id: forbid-submodules
+      - id: mixed-line-ending
+      - id: requirements-txt-fixer
+      - id: trailing-whitespace

CHANGELOG.rst

@@ -25,6 +25,17 @@ Release history
 ^^^^^^^^^^^^^^^
     ..  This extra heading level keeps the ToC from becoming unmanageably long
 
+vNext
+-----
+
+*Unreleased changes*
+
+Other
+~~~~~
+* Use black, isort and doc8 to format code,
+  enforced via pre-commit. (Thanks to `@tim-schilling`_.)
+
+
 v9.0
 ----
 

docs/contributing.rst

@@ -51,8 +51,8 @@ Pull requests
 Pull requests are always welcome to fix bugs and improve support for ESP and Django features.
 
 * Please include test cases.
-* We try to follow the `Django coding style`_
+* We try to follow the `Django coding style`_.
-  (basically, :pep:`8` with longer lines OK).
+* If you install `pre-commit`_, most of the style guidelines will be handled automatically.
 * By submitting a pull request, you're agreeing to release your changes under under
   the same BSD license as the rest of this project.
 * Documentation is appreciated, but not required.
@@ -61,6 +61,8 @@ Pull requests are always welcome to fix bugs and improve support for ESP and Dja
 .. Intentionally point to Django dev branch for coding docs (rather than Django stable):
 .. _Django coding style:
     https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/coding-style/
+.. _pre-commit:
+    https://pre-commit.com/
 
 
 Testing

pyproject.toml

@@ -0,0 +1,19 @@
+[tool.black]
+force-exclude = '^/tests/test_settings/settings_.*\.py'
+max-line-length = 88
+target-version = ["py36"]
+
+[tool.doc8]
+# ignore very long lines in ESP support table:
+ignore-path-errors = ["docs/esps/index.rst;D001"]
+# for now, Anymail allows longer lines in docs source:
+max-line-length = 120
+
+[tool.flake8]
+# See .flake8 file in project root
+
+[tool.isort]
+combine_as_imports = true
+known_first_party = "anymail"
+profile = "black"
+py_version = "36"

setup.py

@@ -32,7 +32,7 @@ with open(path.join(here, 'README.rst'), encoding='utf-8') as f:
 
 # Additional requirements for development/build/release
 requirements_dev = [
-    "flake8",
+    "pre-commit",
     "sphinx",
     "sphinx-rtd-theme",
     "tox",

tox.ini

@@ -74,14 +74,21 @@ basepython = python3.8
 skip_install = true
 passenv =
     CONTINUOUS_INTEGRATION
-	# (but not any of the live test API keys)
+    # Make sure pre-commit can clone hook repos over ssh or http proxy.
+    # https://pre-commit.com/#usage-with-tox
+    SSH_AUTH_SOCK
+    http_proxy
+    https_proxy
+    no_proxy
+    # (but not any of the live test API keys)
 deps =
-    flake8
+    pre-commit
 commands_pre =
     python -VV
-    flake8 --version
+    pre-commit --version
 commands =
-    flake8
+    pre-commit validate-config
+    pre-commit run --all-files
 
 [testenv:docs]
 basepython = python3.8