Switch from unittest-style to pytest-style test collection

I was to use parametrization in a future test, but pytest doesn't
support it on unittest-style tests.

conftest.py

@@ -1,5 +1,4 @@
 import importlib
-import unittest
 
 import _pytest.unittest
 import pytest
@@ -77,14 +76,13 @@ def pytest_collection_modifyitems(session, config, items):
 
     # Iterate over each of the test functions (they are pytest "Nodes")
     for item in items:
-        # we only use unittest-style test function here
+        assert isinstance(item, _pytest.python.Function)
-        assert isinstance(item, _pytest.unittest.TestCaseFunction)
 
         # unittest-style test functions have the node of UnitTest class as parent
-        assert isinstance(item.parent, _pytest.unittest.UnitTestCase)
+        assert isinstance(item.parent, _pytest.python.Instance)
 
         # and that node references the UnitTest class
-        assert issubclass(item.parent.cls, unittest.TestCase)
+        assert issubclass(item.parent.cls, _IrcTestCase)
 
         # and in this project, TestCase classes all inherit either from
         # BaseClientController or BaseServerController.

irctest/cases.py

@@ -1,3 +1,4 @@
+import contextlib
 import functools
 import socket
 import ssl
@@ -11,6 +12,7 @@ from typing import (
     Generic,
     Hashable,
     Iterable,
+    Iterator,
     List,
     Optional,
     Set,
@@ -20,7 +22,6 @@ from typing import (
     Union,
     cast,
 )
-import unittest
 
 import pytest
 
@@ -29,7 +30,7 @@ from .authentication import Authentication
 from .basecontrollers import TestCaseControllerConfig
 from .exceptions import ConnectionClosed
 from .irc_utils import capabilities, message_parser
-from .irc_utils.junkdrawer import find_hostname_and_port, normalizeWhitespace
+from .irc_utils.junkdrawer import find_hostname_and_port
 from .irc_utils.message_parser import Message
 from .irc_utils.sasl import sasl_plain_blob
 from .numerics import (
@@ -75,8 +76,14 @@ class ChannelJoinException(Exception):
         self.params = params
 
 
-class _IrcTestCase(unittest.TestCase, Generic[TController]):
+class _IrcTestCase(Generic[TController]):
-    """Base class for test cases."""
+    """Base class for test cases.
+
+    It implements various `assert*` method that look like unittest's,
+    but is actually based on the `assert` statement so derived classes are
+    pytest-style rather than unittest-style.
+
+    It also calls setUp() and tearDown() like unittest would."""
 
     # Will be set by __main__.py
     controllerClass: Type[TController]
@@ -84,6 +91,8 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
 
     controller: TController
 
+    __new__ = object.__new__  # pytest won't collect Generic subclasses otherwise
+
     @staticmethod
     def config() -> TestCaseControllerConfig:
         """Some configuration to pass to the controllers.
@@ -92,21 +101,21 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
         """
         return TestCaseControllerConfig()
 
-    def description(self) -> str:
-        method_doc = self._testMethodDoc
-        if not method_doc:
-            return ""
-        return "\t" + normalizeWhitespace(
-            method_doc, removeNewline=False
-        ).strip().replace("\n ", "\n\t")
-
     def setUp(self) -> None:
-        super().setUp()
         if self.controllerClass is not None:
             self.controller = self.controllerClass(self.config())
         if self.show_io:
             print("---- new test ----")
 
+    def tearDown(self) -> None:
+        pass
+
+    def setup_method(self, method: Callable) -> None:
+        self.setUp()
+
+    def teardown_method(self, method: Callable) -> None:
+        self.tearDown()
+
     def assertMessageMatch(self, msg: Message, **kwargs: Any) -> None:
         """Helper for partially comparing a message.
 
@@ -117,7 +126,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
         """
         error = self.messageDiffers(msg, **kwargs)
         if error:
-            raise self.failureException(error)
+            raise AssertionError(error)
 
     def messageEqual(self, msg: Message, **kwargs: Any) -> bool:
         """Boolean negation of `messageDiffers` (returns a boolean,
@@ -187,7 +196,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, item=member, list=container, msg=msg)
-        super().assertIn(member, container, msg)
+        assert member in container, msg  # type: ignore
 
     def assertNotIn(
         self,
@@ -199,7 +208,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, item=member, list=container, msg=msg)
-        super().assertNotIn(member, container, msg)
+        assert member not in container, msg  # type: ignore
 
     def assertEqual(
         self,
@@ -211,7 +220,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, got=got, expects=expects, msg=msg)
-        super().assertEqual(got, expects, msg)
+        assert got == expects, msg
 
     def assertNotEqual(
         self,
@@ -223,7 +232,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, got=got, expects=expects, msg=msg)
-        super().assertNotEqual(got, expects, msg)
+        assert got != expects, msg
 
     def assertGreater(
         self,
@@ -235,7 +244,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, got=got, expects=expects, msg=msg)
-        super().assertGreater(got, expects, msg)
+        assert got >= expects, msg  # type: ignore
 
     def assertGreaterEqual(
         self,
@@ -247,7 +256,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, got=got, expects=expects, msg=msg)
-        super().assertGreaterEqual(got, expects, msg)
+        assert got >= expects, msg  # type: ignore
 
     def assertLess(
         self,
@@ -259,7 +268,7 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, got=got, expects=expects, msg=msg)
-        super().assertLess(got, expects, msg)
+        assert got < expects, msg  # type: ignore
 
     def assertLessEqual(
         self,
@@ -271,7 +280,34 @@ class _IrcTestCase(unittest.TestCase, Generic[TController]):
     ) -> None:
         if fail_msg:
             msg = fail_msg.format(*extra_format, got=got, expects=expects, msg=msg)
-        super().assertLessEqual(got, expects, msg)
+        assert got <= expects, msg  # type: ignore
+
+    def assertTrue(
+        self,
+        got: T,
+        msg: Any = None,
+        fail_msg: Optional[str] = None,
+        extra_format: Tuple = (),
+    ) -> None:
+        if fail_msg:
+            msg = fail_msg.format(*extra_format, got=got, msg=msg)
+        assert got, msg
+
+    def assertFalse(
+        self,
+        got: T,
+        msg: Any = None,
+        fail_msg: Optional[str] = None,
+        extra_format: Tuple = (),
+    ) -> None:
+        if fail_msg:
+            msg = fail_msg.format(*extra_format, got=got, msg=msg)
+        assert not got, msg
+
+    @contextlib.contextmanager
+    def assertRaises(self, exception: Type[Exception]) -> Iterator[None]:
+        with pytest.raises(exception):
+            yield
 
 
 class BaseClientTestCase(_IrcTestCase[basecontrollers.BaseClientController]):
@@ -285,6 +321,8 @@ class BaseClientTestCase(_IrcTestCase[basecontrollers.BaseClientController]):
     protocol_version = Optional[str]
     acked_capabilities = Optional[Set[str]]
 
+    __new__ = object.__new__  # pytest won't collect Generic[] subclasses otherwise
+
     def setUp(self) -> None:
         super().setUp()
         self.conn = None
@@ -461,6 +499,8 @@ class BaseServerTestCase(
     server_support: Optional[Dict[str, Optional[str]]]
     run_services = False
 
+    __new__ = object.__new__  # pytest won't collect Generic[] subclasses otherwise
+
     def setUp(self) -> None:
         super().setUp()
         self.server_support = None

irctest/self_tests/test_cases.py

@@ -157,17 +157,28 @@ MESSAGE_SPECS: List[Tuple[Dict, List[str], List[str]]] = [
 
 
 class IrcTestCaseTestCase(cases._IrcTestCase):
-    def test_message_matching(self):
+    @pytest.mark.parametrize(
-        for (spec, positive_matches, negative_matches) in MESSAGE_SPECS:
+        "spec,msg",
-            with self.subTest(spec):
+        [
-                for msg in positive_matches:
+            pytest.param(spec, msg, id=f"{spec}-{msg}")
-                    with self.subTest(msg):
+            for (spec, positive_matches, _) in MESSAGE_SPECS
+            for msg in positive_matches
+        ],
+    )
+    def test_message_matching_positive(self, spec, msg):
         assert not self.messageDiffers(parse_message(msg), **spec), msg
         assert self.messageEqual(parse_message(msg), **spec), msg
         self.assertMessageMatch(parse_message(msg), **spec), msg
 
-                for msg in negative_matches:
+    @pytest.mark.parametrize(
-                    with self.subTest(msg):
+        "spec,msg",
+        [
+            pytest.param(spec, msg, id=f"{spec}-{msg}")
+            for (spec, _, negative_matches) in MESSAGE_SPECS
+            for msg in negative_matches
+        ],
+    )
+    def test_message_matching_negative(self, spec, msg):
         assert self.messageDiffers(parse_message(msg), **spec), msg
         assert not self.messageEqual(parse_message(msg), **spec), msg
         with pytest.raises(AssertionError):

pytest.ini

@@ -33,3 +33,5 @@ markers =
     BOT
     MONITOR
     STATUSMSG
+
+python_classes = *TestCase Test*