[3.11] gh-97837: Change deprecation warning message in `unittest` (GH-97838)

(cherry picked from commit c3648f4e)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>

Lib/unittest/async_case.py

@@ -88,7 +88,7 @@ def _callSetUp(self):
 
     def _callTestMethod(self, method):
         if self._callMaybeAsync(method) is not None:
-            warnings.warn(f'It is deprecated to return a value!=None from a '
+            warnings.warn(f'It is deprecated to return a value that is not None from a '
                           f'test case ({method})', DeprecationWarning, stacklevel=4)
 
     def _callTearDown(self):

Lib/unittest/case.py

@@ -577,7 +577,7 @@ def _callSetUp(self):
 
     def _callTestMethod(self, method):
         if method() is not None:
-            warnings.warn(f'It is deprecated to return a value!=None from a '
+            warnings.warn(f'It is deprecated to return a value that is not None from a '
                           f'test case ({method})', DeprecationWarning, stacklevel=3)
 
     def _callTearDown(self):

Lib/unittest/test/test_async_case.py

@@ -277,25 +277,36 @@ async def on_cleanup2(self):
         self.assertEqual(events, ['asyncSetUp', 'test', 'asyncTearDown', 'cleanup2', 'cleanup1'])
 
     def test_deprecation_of_return_val_from_test(self):
-        # Issue 41322 - deprecate return of value!=None from a test
+        # Issue 41322 - deprecate return of value that is not None from a test
+        class Nothing:
+            def __eq__(self, o):
+                return o is None
         class Test(unittest.IsolatedAsyncioTestCase):
             async def test1(self):
                 return 1
             async def test2(self):
                 yield 1
+            async def test3(self):
+                return Nothing()
 
         with self.assertWarns(DeprecationWarning) as w:
             Test('test1').run()
-        self.assertIn('It is deprecated to return a value!=None', str(w.warning))
+        self.assertIn('It is deprecated to return a value that is not None', str(w.warning))
         self.assertIn('test1', str(w.warning))
         self.assertEqual(w.filename, __file__)
 
         with self.assertWarns(DeprecationWarning) as w:
             Test('test2').run()
-        self.assertIn('It is deprecated to return a value!=None', str(w.warning))
+        self.assertIn('It is deprecated to return a value that is not None', str(w.warning))
         self.assertIn('test2', str(w.warning))
         self.assertEqual(w.filename, __file__)
 
+        with self.assertWarns(DeprecationWarning) as w:
+            Test('test3').run()
+        self.assertIn('It is deprecated to return a value that is not None', str(w.warning))
+        self.assertIn('test3', str(w.warning))
+        self.assertEqual(w.filename, __file__)
+
     def test_cleanups_interleave_order(self):
         events = []
 

Lib/unittest/test/test_case.py

@@ -307,25 +307,36 @@ def test(self):
         Foo('test').run()
 
     def test_deprecation_of_return_val_from_test(self):
-        # Issue 41322 - deprecate return of value!=None from a test
+        # Issue 41322 - deprecate return of value that is not None from a test
+        class Nothing:
+            def __eq__(self, o):
+                return o is None
         class Foo(unittest.TestCase):
             def test1(self):
                 return 1
             def test2(self):
                 yield 1
+            def test3(self):
+                return Nothing()
 
         with self.assertWarns(DeprecationWarning) as w:
             Foo('test1').run()
-        self.assertIn('It is deprecated to return a value!=None', str(w.warning))
+        self.assertIn('It is deprecated to return a value that is not None', str(w.warning))
         self.assertIn('test1', str(w.warning))
         self.assertEqual(w.filename, __file__)
 
         with self.assertWarns(DeprecationWarning) as w:
             Foo('test2').run()
-        self.assertIn('It is deprecated to return a value!=None', str(w.warning))
+        self.assertIn('It is deprecated to return a value that is not None', str(w.warning))
         self.assertIn('test2', str(w.warning))
         self.assertEqual(w.filename, __file__)
 
+        with self.assertWarns(DeprecationWarning) as w:
+            Foo('test3').run()
+        self.assertIn('It is deprecated to return a value that is not None', str(w.warning))
+        self.assertIn('test3', str(w.warning))
+        self.assertEqual(w.filename, __file__)
+
     def _check_call_order__subtests(self, result, events, expected_events):
         class Foo(Test.LoggingTestCase):
             def test(self):

Misc/NEWS.d/next/Library/2022-10-04-21-21-41.gh-issue-97837.19q-eg.rst

+Change deprecate warning message in :mod:`unittest` from
+
+``It is deprecated to return a value!=None``
+
+to
+
+``It is deprecated to return a value that is not None from a test case``