[3.11] gh-84867: Do not load tests from TestCase and FunctionTestCase (GH-100497) (GH-109328)

(cherry picked from commit 66d1d7eb067d445f1ade151f4a6db3864dd9109f)

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

1 files changed, 17 insertions, 5 deletions

diff --git a/Lib/unittest/loader.py b/Lib/unittest/loader.py
index 7e6ce2f..f4e3d6e 100644
--- a/Lib/unittest/loader.py
+++ b/Lib/unittest/loader.py
@@ -87,9 +87,13 @@ class TestLoader(object):
             raise TypeError("Test cases should not be derived from "
                             "TestSuite. Maybe you meant to derive from "
                             "TestCase?")
-        testCaseNames = self.getTestCaseNames(testCaseClass)
-        if not testCaseNames and hasattr(testCaseClass, 'runTest'):
-            testCaseNames = ['runTest']
+        if testCaseClass in (case.TestCase, case.FunctionTestCase):
+            # We don't load any tests from base types that should not be loaded.
+            testCaseNames = []
+        else:
+            testCaseNames = self.getTestCaseNames(testCaseClass)
+            if not testCaseNames and hasattr(testCaseClass, 'runTest'):
+                testCaseNames = ['runTest']
         loaded_suite = self.suiteClass(map(testCaseClass, testCaseNames))
         return loaded_suite
 
@@ -120,7 +124,11 @@ class TestLoader(object):
         tests = []
         for name in dir(module):
             obj = getattr(module, name)
-            if isinstance(obj, type) and issubclass(obj, case.TestCase):
+            if (
+                isinstance(obj, type)
+                and issubclass(obj, case.TestCase)
+                and obj not in (case.TestCase, case.FunctionTestCase)
+            ):
                 tests.append(self.loadTestsFromTestCase(obj))
 
         load_tests = getattr(module, 'load_tests', None)
@@ -189,7 +197,11 @@ class TestLoader(object):
 
         if isinstance(obj, types.ModuleType):
             return self.loadTestsFromModule(obj)
-        elif isinstance(obj, type) and issubclass(obj, case.TestCase):
+        elif (
+            isinstance(obj, type)
+            and issubclass(obj, case.TestCase)
+            and obj not in (case.TestCase, case.FunctionTestCase)
+        ):
             return self.loadTestsFromTestCase(obj)
         elif (isinstance(obj, types.FunctionType) and
               isinstance(parent, type) and