[3.6] bpo-30523, bpo-30764, bpo-30776: Sync regrtest from master (#2441)

* bpo-30523: regrtest --list-cases --match (#2401)

* regrtest --list-cases now supports --match and --match-file options.
  Example: ./python -m test --list-cases -m FileTests test_os
* --list-cases now also sets support.verbose to False to prevent
  messages to stdout when loading test modules.
* Add support._match_test() private function.
(cherry picked from commit ace56d583664f855d89d1219ece7c21c2fddcf30)

* bpo-30764: regrtest: add --fail-env-changed option (#2402)

* bpo-30764: regrtest: change exit code on failure

* Exit code 2 if failed tests ("bad")
* Exit code 3 if interrupted

* bpo-30764: regrtest: add --fail-env-changed option

If the option is set, mark a test as failed if it alters the
environment, for example if it creates a file without removing it.

(cherry picked from commit 63f54c68936d648c70ca411661e4208329edcf26)

* bpo-30776: reduce regrtest -R false positives (#2422)

* Change the regrtest --huntrleaks checker to decide if a test file
  leaks or not. Require that each run leaks at least 1 reference.
* Warmup runs are now completely ignored: ignored in the checker test
  and not used anymore to compute the sum.
* Add an unit test for a reference leak.

Example of reference differences previously considered a failure
(leak) and now considered as success (success, no leak):

    [3, 0, 0]
    [0, 1, 0]
    [8, -8, 1]
(cherry picked from commit 48b5c422ffb03affb00c184b9a99e5537be92732)

1 files changed, 83 insertions, 30 deletions

diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index 5c6154a..a544f88 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -377,19 +377,19 @@ class BaseTestCase(unittest.TestCase):
         return list(match.group(1) for match in parser)
 
     def check_executed_tests(self, output, tests, skipped=(), failed=(),
-                             omitted=(), randomize=False, interrupted=False):
+                             env_changed=(), omitted=(),
+                             randomize=False, interrupted=False,
+                             fail_env_changed=False):
         if isinstance(tests, str):
             tests = [tests]
         if isinstance(skipped, str):
             skipped = [skipped]
         if isinstance(failed, str):
             failed = [failed]
+        if isinstance(env_changed, str):
+            env_changed = [env_changed]
         if isinstance(omitted, str):
             omitted = [omitted]
-        ntest = len(tests)
-        nskipped = len(skipped)
-        nfailed = len(failed)
-        nomitted = len(omitted)
 
         executed = self.parse_executed_tests(output)
         if randomize:
@@ -415,11 +415,17 @@ class BaseTestCase(unittest.TestCase):
             regex = list_regex('%s test%s failed', failed)
             self.check_line(output, regex)
 
+        if env_changed:
+            regex = list_regex('%s test%s altered the execution environment',
+                               env_changed)
+            self.check_line(output, regex)
+
         if omitted:
             regex = list_regex('%s test%s omitted', omitted)
             self.check_line(output, regex)
 
-        good = ntest - nskipped - nfailed - nomitted
+        good = (len(tests) - len(skipped) - len(failed)
+                - len(omitted) - len(env_changed))
         if good:
             regex = r'%s test%s OK\.$' % (good, plural(good))
             if not skipped and not failed and good > 1:
@@ -429,10 +435,12 @@ class BaseTestCase(unittest.TestCase):
         if interrupted:
             self.check_line(output, 'Test suite interrupted by signal SIGINT.')
 
-        if nfailed:
+        if failed:
             result = 'FAILURE'
         elif interrupted:
             result = 'INTERRUPTED'
+        elif fail_env_changed and env_changed:
+            result = 'ENV CHANGED'
         else:
             result = 'SUCCESS'
         self.check_line(output, 'Tests result: %s' % result)
@@ -604,7 +612,7 @@ class ArgsTestCase(BaseTestCase):
         test_failing = self.create_test('failing', code=code)
         tests = [test_ok, test_failing]
 
-        output = self.run_tests(*tests, exitcode=1)
+        output = self.run_tests(*tests, exitcode=2)
         self.check_executed_tests(output, tests, failed=test_failing)
 
     def test_resources(self):
@@ -703,7 +711,7 @@ class ArgsTestCase(BaseTestCase):
     def test_interrupted(self):
         code = TEST_INTERRUPTED
         test = self.create_test('sigint', code=code)
-        output = self.run_tests(test, exitcode=1)
+        output = self.run_tests(test, exitcode=130)
         self.check_executed_tests(output, test, omitted=test,
                                   interrupted=True)
 
@@ -732,7 +740,7 @@ class ArgsTestCase(BaseTestCase):
                 args = ("--slowest", "-j2", test)
             else:
                 args = ("--slowest", test)
-            output = self.run_tests(*args, exitcode=1)
+            output = self.run_tests(*args, exitcode=130)
             self.check_executed_tests(output, test,
                                       omitted=test, interrupted=True)
 
@@ -772,9 +780,43 @@ class ArgsTestCase(BaseTestCase):
                         builtins.__dict__['RUN'] = 1
         """)
         test = self.create_test('forever', code=code)
-        output = self.run_tests('--forever', test, exitcode=1)
+        output = self.run_tests('--forever', test, exitcode=2)
         self.check_executed_tests(output, [test]*3, failed=test)
 
+    def check_leak(self, code, what):
+        test = self.create_test('huntrleaks', code=code)
+
+        filename = 'reflog.txt'
+        self.addCleanup(support.unlink, filename)
+        output = self.run_tests('--huntrleaks', '3:3:', test,
+                                exitcode=2,
+                                stderr=subprocess.STDOUT)
+        self.check_executed_tests(output, [test], failed=test)
+
+        line = 'beginning 6 repetitions\n123456\n......\n'
+        self.check_line(output, re.escape(line))
+
+        line2 = '%s leaked [1, 1, 1] %s, sum=3\n' % (test, what)
+        self.assertIn(line2, output)
+
+        with open(filename) as fp:
+            reflog = fp.read()
+            self.assertIn(line2, reflog)
+
+    @unittest.skipUnless(Py_DEBUG, 'need a debug build')
+    def test_huntrleaks(self):
+        # test --huntrleaks
+        code = textwrap.dedent("""
+            import unittest
+
+            GLOBAL_LIST = []
+
+            class RefLeakTest(unittest.TestCase):
+                def test_leak(self):
+                    GLOBAL_LIST.append(object())
+        """)
+        self.check_leak(code, 'references')
+
     @unittest.skipUnless(Py_DEBUG, 'need a debug build')
     def test_huntrleaks_fd_leak(self):
         # test --huntrleaks for file descriptor leak
@@ -799,24 +841,7 @@ class ArgsTestCase(BaseTestCase):
                     fd = os.open(__file__, os.O_RDONLY)
                     # bug: never cloes the file descriptor
         """)
-        test = self.create_test('huntrleaks', code=code)
-
-        filename = 'reflog.txt'
-        self.addCleanup(support.unlink, filename)
-        output = self.run_tests('--huntrleaks', '3:3:', test,
-                                exitcode=1,
-                                stderr=subprocess.STDOUT)
-        self.check_executed_tests(output, [test], failed=test)
-
-        line = 'beginning 6 repetitions\n123456\n......\n'
-        self.check_line(output, re.escape(line))
-
-        line2 = '%s leaked [1, 1, 1] file descriptors, sum=3\n' % test
-        self.assertIn(line2, output)
-
-        with open(filename) as fp:
-            reflog = fp.read()
-            self.assertIn(line2, reflog)
+        self.check_leak(code, 'file descriptors')
 
     def test_list_tests(self):
         # test --list-tests
@@ -837,11 +862,20 @@ class ArgsTestCase(BaseTestCase):
                     pass
         """)
         testname = self.create_test(code=code)
+
+        # Test --list-cases
         all_methods = ['%s.Tests.test_method1' % testname,
                        '%s.Tests.test_method2' % testname]
         output = self.run_tests('--list-cases', testname)
         self.assertEqual(output.splitlines(), all_methods)
 
+        # Test --list-cases with --match
+        all_methods = ['%s.Tests.test_method1' % testname]
+        output = self.run_tests('--list-cases',
+                                '-m', 'test_method1',
+                                testname)
+        self.assertEqual(output.splitlines(), all_methods)
+
     def test_crashed(self):
         # Any code which causes a crash
         code = 'import faulthandler; faulthandler._sigsegv()'
@@ -849,7 +883,7 @@ class ArgsTestCase(BaseTestCase):
         ok_test = self.create_test(name="ok")
 
         tests = [crash_test, ok_test]
-        output = self.run_tests("-j2", *tests, exitcode=1)
+        output = self.run_tests("-j2", *tests, exitcode=2)
         self.check_executed_tests(output, tests, failed=crash_test,
                                   randomize=True)
 
@@ -898,6 +932,25 @@ class ArgsTestCase(BaseTestCase):
         subset = ['test_method1', 'test_method3']
         self.assertEqual(methods, subset)
 
+    def test_env_changed(self):
+        code = textwrap.dedent("""
+            import unittest
+
+            class Tests(unittest.TestCase):
+                def test_env_changed(self):
+                    open("env_changed", "w").close()
+        """)
+        testname = self.create_test(code=code)
+
+        # don't fail by default
+        output = self.run_tests(testname)
+        self.check_executed_tests(output, [testname], env_changed=testname)
+
+        # fail with --fail-env-changed
+        output = self.run_tests("--fail-env-changed", testname, exitcode=3)
+        self.check_executed_tests(output, [testname], env_changed=testname,
+                                  fail_env_changed=True)
+
 
 if __name__ == '__main__':
     unittest.main()