bpo-32071: Fix regression and add What's New entry

Doc/whatsnew/3.7.rst

@@ -398,6 +398,15 @@ Added functions :func:`time.thread_time` and :func:`time.thread_time_ns`
 to get per-thread CPU time measurements.
 (Contributed by Antoine Pitrou in :issue:`32025`.)
 
+
+unittest
+--------
+Added new command-line option ``-k`` to filter tests to run with a substring or
+Unix shell-like pattern.  For example, ``python -m unittest -k foo`` runs the
+tests ``foo_tests.SomeTest.test_something``, ``bar_tests.SomeTest.test_foo``,
+but not ``bar_tests.FooTest.test_something``.
+
+
 unittest.mock
 -------------
 

Lib/unittest/loader.py

@@ -224,9 +224,10 @@ def getTestCaseNames(self, testCaseClass):
         """Return a sorted sequence of method names found within testCaseClass
         """
         def shouldIncludeMethod(attrname):
+            if not attrname.startswith(self.testMethodPrefix):
+                return False
             testFunc = getattr(testCaseClass, attrname)
-            isTestMethod = attrname.startswith(self.testMethodPrefix) and callable(testFunc)
-            if not isTestMethod:
+            if not callable(testFunc):
                 return False
             fullName = '%s.%s' % (testCaseClass.__module__, testFunc.__qualname__)
             return self.testNamePatterns is None or \

Lib/unittest/test/test_loader.py

@@ -1253,6 +1253,29 @@ def foobar(self): pass
         loader.testNamePatterns = ['*my*']
         self.assertEqual(loader.getTestCaseNames(MyTest), [])
 
+    # "Return a sorted sequence of method names found within testCaseClass"
+    #
+    # If TestLoader.testNamePatterns is set, only tests that match one of these
+    # patterns should be included.
+    #
+    # For backwards compatibility reasons (see bpo-32071), the check may only
+    # touch a TestCase's attribute if it starts with the test method prefix.
+    def test_getTestCaseNames__testNamePatterns__attribute_access_regression(self):
+        class Trap:
+            def __get__(*ignored):
+                self.fail('Non-test attribute accessed')
+
+        class MyTest(unittest.TestCase):
+            def test_1(self): pass
+            foobar = Trap()
+
+        loader = unittest.TestLoader()
+        self.assertEqual(loader.getTestCaseNames(MyTest), ['test_1'])
+
+        loader = unittest.TestLoader()
+        loader.testNamePatterns = []
+        self.assertEqual(loader.getTestCaseNames(MyTest), [])
+
     ################################################################
     ### /Tests for TestLoader.getTestCaseNames()