Move tests out of app module

(Directory structure as suggested in
[Django testing docs][1].)

[1]: https://docs.djangoproject.com/en/1.9/topics/testing/advanced/#using-the-django-test-runner-to-test-reusable-applications

tests/test_postmark_integration.py

@@ -0,0 +1,82 @@
+from __future__ import unicode_literals
+
+from django.test import SimpleTestCase
+from django.test.utils import override_settings
+
+from anymail.exceptions import AnymailAPIError
+from anymail.message import AnymailMessage
+
+from .utils import AnymailTestMixin, sample_image_path
+
+
+@override_settings(ANYMAIL_POSTMARK_SERVER_TOKEN="POSTMARK_API_TEST",
+                   EMAIL_BACKEND="anymail.backends.postmark.PostmarkBackend")
+class PostmarkBackendIntegrationTests(SimpleTestCase, AnymailTestMixin):
+    """Postmark API integration tests
+
+    These tests run against the **live** Postmark API, but using a
+    test key that's not capable of sending actual email.
+    """
+
+    def setUp(self):
+        super(PostmarkBackendIntegrationTests, self).setUp()
+        self.message = AnymailMessage('Anymail Postmark integration test', 'Text content',
+                                      'from@example.com', ['to@example.com'])
+        self.message.attach_alternative('<p>HTML content</p>', "text/html")
+
+    def test_simple_send(self):
+        # Example of getting the SendGrid send status and message id from the message
+        sent_count = self.message.send()
+        self.assertEqual(sent_count, 1)
+
+        anymail_status = self.message.anymail_status
+        sent_status = anymail_status.recipients['to@example.com'].status
+        message_id = anymail_status.recipients['to@example.com'].message_id
+
+        self.assertEqual(sent_status, 'sent')
+        self.assertGreater(len(message_id), 0)  # non-empty string
+        self.assertEqual(anymail_status.status, {sent_status})  # set of all recipient statuses
+        self.assertEqual(anymail_status.message_id, message_id)
+
+    def test_all_options(self):
+        message = AnymailMessage(
+            subject="Anymail all-options integration test",
+            body="This is the text body",
+            from_email="Test From <from@example.com>",
+            to=["to1@example.com", "Recipient 2 <to2@example.com>"],
+            cc=["cc1@example.com", "Copy 2 <cc2@example.com>"],
+            bcc=["bcc1@example.com", "Blind Copy 2 <bcc2@example.com>"],
+            reply_to=["reply1@example.com", "Reply 2 <reply2@example.com>"],
+            headers={"X-Anymail-Test": "value"},
+
+            # no metadata, send_at, track_clicks support
+            tags=["tag 1"],  # max one tag
+            track_opens=True,
+        )
+        message.attach("attachment1.txt", "Here is some\ntext for you", "text/plain")
+        message.attach("attachment2.csv", "ID,Name\n1,Amy Lina", "text/csv")
+        cid = message.attach_inline_image_file(sample_image_path())
+        message.attach_alternative(
+            "<p><b>HTML:</b> with <a href='http://example.com'>link</a>"
+            "and image: <img src='cid:%s'></div>" % cid,
+            "text/html")
+
+        message.send()
+        self.assertEqual(message.anymail_status.status, {'sent'})
+
+    def test_invalid_from(self):
+        self.message.from_email = 'webmaster@localhost'  # Django's default From
+        with self.assertRaises(AnymailAPIError) as cm:
+            self.message.send()
+        err = cm.exception
+        self.assertEqual(err.status_code, 422)
+        self.assertIn("Invalid 'From' address", str(err))
+
+    @override_settings(ANYMAIL_POSTMARK_SERVER_TOKEN="Hey, that's not a server token!")
+    def test_invalid_server_token(self):
+        with self.assertRaises(AnymailAPIError) as cm:
+            self.message.send()
+        err = cm.exception
+        self.assertEqual(err.status_code, 401)
+        # Make sure the exception message includes Postmark's response:
+        self.assertIn("Bad or missing Server API token", str(err))