bpo-36725: regrtest: add TestResult type (GH-12960)

* Add TestResult and MultiprocessResult types to ensure that results
  always have the same fields.
* runtest() now handles KeyboardInterrupt
* accumulate_result() and format_test_result() now takes a TestResult
* cleanup_test_droppings() is now called by runtest() and mark the
  test as ENV_CHANGED if the test leaks support.TESTFN file.
* runtest() now includes code "around" the test in the test timing
* Add print_warning() in test.libregrtest.utils to standardize how
  libregrtest logs warnings to ease parsing the test output.
* support.unload() is now called with abstest rather than test_name
* Rename 'test' variable/parameter to 'test_name'
* dash_R(): remove unused the_module parameter
* Remove unused imports

8 files changed, 286 insertions, 208 deletions

diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
index d20e174..ef1336a 100644
--- a/Lib/test/libregrtest/main.py
+++ b/Lib/test/libregrtest/main.py
@@ -105,26 +105,30 @@ class Regrtest:
         # used by --junit-xml
         self.testsuite_xml = None
 
-    def accumulate_result(self, test, result):
-        ok, test_time, xml_data = result
+    def accumulate_result(self, result):
+        test_name = result.test_name
+        ok = result.result
+
         if ok not in (CHILD_ERROR, INTERRUPTED):
-            self.test_times.append((test_time, test))
+            self.test_times.append((result.test_time, test_name))
+
         if ok == PASSED:
-            self.good.append(test)
+            self.good.append(test_name)
         elif ok in (FAILED, CHILD_ERROR):
-            self.bad.append(test)
+            self.bad.append(test_name)
         elif ok == ENV_CHANGED:
-            self.environment_changed.append(test)
+            self.environment_changed.append(test_name)
         elif ok == SKIPPED:
-            self.skipped.append(test)
+            self.skipped.append(test_name)
         elif ok == RESOURCE_DENIED:
-            self.skipped.append(test)
-            self.resource_denieds.append(test)
+            self.skipped.append(test_name)
+            self.resource_denieds.append(test_name)
         elif ok == TEST_DID_NOT_RUN:
-            self.run_no_tests.append(test)
+            self.run_no_tests.append(test_name)
         elif ok != INTERRUPTED:
             raise ValueError("invalid test result: %r" % ok)
 
+        xml_data = result.xml_data
         if xml_data:
             import xml.etree.ElementTree as ET
             for e in xml_data:
@@ -134,7 +138,7 @@ class Regrtest:
                     print(xml_data, file=sys.__stderr__)
                     raise
 
-    def display_progress(self, test_index, test):
+    def display_progress(self, test_index, text):
         if self.ns.quiet:
             return
 
@@ -143,7 +147,7 @@ class Regrtest:
         fails = len(self.bad) + len(self.environment_changed)
         if fails and not self.ns.pgo:
             line = f"{line}/{fails}"
-        line = f"[{line}] {test}"
+        line = f"[{line}] {text}"
 
         # add the system load prefix: "load avg: 1.80 "
         if self.getloadavg:
@@ -275,13 +279,13 @@ class Regrtest:
         support.verbose = False
         support.set_match_tests(self.ns.match_tests)
 
-        for test in self.selected:
-            abstest = get_abs_module(self.ns, test)
+        for test_name in self.selected:
+            abstest = get_abs_module(self.ns, test_name)
             try:
                 suite = unittest.defaultTestLoader.loadTestsFromName(abstest)
                 self._list_cases(suite)
             except unittest.SkipTest:
-                self.skipped.append(test)
+                self.skipped.append(test_name)
 
         if self.skipped:
             print(file=sys.stderr)
@@ -298,19 +302,19 @@ class Regrtest:
         print()
         print("Re-running failed tests in verbose mode")
         self.rerun = self.bad[:]
-        for test in self.rerun:
-            print("Re-running test %r in verbose mode" % test, flush=True)
-            try:
-                self.ns.verbose = True
-                ok = runtest(self.ns, test)
-            except KeyboardInterrupt:
-                self.interrupted = True
+        for test_name in self.rerun:
+            print("Re-running test %r in verbose mode" % test_name, flush=True)
+            self.ns.verbose = True
+            ok = runtest(self.ns, test_name)
+
+            if ok[0] in {PASSED, ENV_CHANGED, SKIPPED, RESOURCE_DENIED}:
+                self.bad.remove(test_name)
+
+            if ok.result == INTERRUPTED:
                 # print a newline separate from the ^C
                 print()
+                self.interrupted = True
                 break
-            else:
-                if ok[0] in {PASSED, ENV_CHANGED, SKIPPED, RESOURCE_DENIED}:
-                    self.bad.remove(test)
         else:
             if self.bad:
                 print(count(len(self.bad), 'test'), "failed again:")
@@ -348,8 +352,8 @@ class Regrtest:
             self.test_times.sort(reverse=True)
             print()
             print("10 slowest tests:")
-            for time, test in self.test_times[:10]:
-                print("- %s: %s" % (test, format_duration(time)))
+            for test_time, test in self.test_times[:10]:
+                print("- %s: %s" % (test, format_duration(test_time)))
 
         if self.bad:
             print()
@@ -387,10 +391,10 @@ class Regrtest:
         print("Run tests sequentially")
 
         previous_test = None
-        for test_index, test in enumerate(self.tests, 1):
+        for test_index, test_name in enumerate(self.tests, 1):
             start_time = time.monotonic()
 
-            text = test
+            text = test_name
             if previous_test:
                 text = '%s -- %s' % (text, previous_test)
             self.display_progress(test_index, text)
@@ -398,22 +402,20 @@ class Regrtest:
             if self.tracer:
                 # If we're tracing code coverage, then we don't exit with status
                 # if on a false return value from main.
-                cmd = ('result = runtest(self.ns, test); '
-                       'self.accumulate_result(test, result)')
+                cmd = ('result = runtest(self.ns, test_name); '
+                       'self.accumulate_result(result)')
                 ns = dict(locals())
                 self.tracer.runctx(cmd, globals=globals(), locals=ns)
                 result = ns['result']
             else:
-                try:
-                    result = runtest(self.ns, test)
-                except KeyboardInterrupt:
-                    self.interrupted = True
-                    self.accumulate_result(test, (INTERRUPTED, None, None))
-                    break
-                else:
-                    self.accumulate_result(test, result)
-
-            previous_test = format_test_result(test, result[0])
+                result = runtest(self.ns, test_name)
+                self.accumulate_result(result)
+
+            if result.result == INTERRUPTED:
+                self.interrupted = True
+                break
+
+            previous_test = format_test_result(result)
             test_time = time.monotonic() - start_time
             if test_time >= PROGRESS_MIN_TIME:
                 previous_test = "%s in %s" % (previous_test, format_duration(test_time))
@@ -441,8 +443,8 @@ class Regrtest:
 
     def _test_forever(self, tests):
         while True:
-            for test in tests:
-                yield test
+            for test_name in tests:
+                yield test_name
                 if self.bad:
                     return
                 if self.ns.fail_env_changed and self.environment_changed:
diff --git a/Lib/test/libregrtest/refleak.py b/Lib/test/libregrtest/refleak.py
index 235d6bf..8d22123 100644
--- a/Lib/test/libregrtest/refleak.py
+++ b/Lib/test/libregrtest/refleak.py
@@ -1,4 +1,3 @@
-import errno
 import os
 import re
 import sys
@@ -18,7 +17,7 @@ except ImportError:
                 cls._abc_negative_cache, cls._abc_negative_cache_version)
 
 
-def dash_R(ns, the_module, test_name, test_func):
+def dash_R(ns, test_name, test_func):
     """Run a test multiple times, looking for reference leaks.
 
     Returns:
diff --git a/Lib/test/libregrtest/runtest.py b/Lib/test/libregrtest/runtest.py
index 0a9533c..55913b3 100644
--- a/Lib/test/libregrtest/runtest.py
+++ b/Lib/test/libregrtest/runtest.py
@@ -1,4 +1,6 @@
+import collections
 import faulthandler
+import functools
 import importlib
 import io
 import os
@@ -9,6 +11,7 @@ import unittest
 from test import support
 from test.libregrtest.refleak import dash_R, clear_caches
 from test.libregrtest.save_env import saved_test_environment
+from test.libregrtest.utils import print_warning
 
 
 # Test result constants.
@@ -55,9 +58,17 @@ STDTESTS = [
 NOTTESTS = set()
 
 
-def format_test_result(test_name, result):
-    fmt = _FORMAT_TEST_RESULT.get(result, "%s")
-    return fmt % test_name
+# used by --findleaks, store for gc.garbage
+found_garbage = []
+
+
+def format_test_result(result):
+    fmt = _FORMAT_TEST_RESULT.get(result.result, "%s")
+    return fmt % result.test_name
+
+
+def findtestdir(path=None):
+    return path or os.path.dirname(os.path.dirname(__file__)) or os.curdir
 
 
 def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):
@@ -73,48 +84,34 @@ def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):
     return stdtests + sorted(tests)
 
 
-def get_abs_module(ns, test):
-    if test.startswith('test.') or ns.testdir:
-        return test
+def get_abs_module(ns, test_name):
+    if test_name.startswith('test.') or ns.testdir:
+        return test_name
     else:
-        # Always import it from the test package
-        return 'test.' + test
-
+        # Import it from the test package
+        return 'test.' + test_name
 
-def runtest(ns, test):
-    """Run a single test.
-
-    ns -- regrtest namespace of options
-    test -- the name of the test
 
-    Returns the tuple (result, test_time, xml_data), where result is one
-    of the constants:
-
-        INTERRUPTED      KeyboardInterrupt when run under -j
-        RESOURCE_DENIED  test skipped because resource denied
-        SKIPPED          test skipped for some other reason
-        ENV_CHANGED      test failed because it changed the execution environment
-        FAILED           test failed
-        PASSED           test passed
-        EMPTY_TEST_SUITE test ran no subtests.
+TestResult = collections.namedtuple('TestResult',
+    'test_name result test_time xml_data')
 
-    If ns.xmlpath is not None, xml_data is a list containing each
-    generated testsuite element.
-    """
+def _runtest(ns, test_name):
+    # Handle faulthandler timeout, capture stdout+stderr, XML serialization
+    # and measure time.
 
     output_on_failure = ns.verbose3
 
     use_timeout = (ns.timeout is not None)
     if use_timeout:
         faulthandler.dump_traceback_later(ns.timeout, exit=True)
+
+    start_time = time.perf_counter()
     try:
         support.set_match_tests(ns.match_tests)
-        # reset the environment_altered flag to detect if a test altered
-        # the environment
-        support.environment_altered = False
         support.junit_xml_list = xml_list = [] if ns.xmlpath else None
         if ns.failfast:
             support.failfast = True
+
         if output_on_failure:
             support.verbose = True
 
@@ -124,8 +121,9 @@ def runtest(ns, test):
             try:
                 sys.stdout = stream
                 sys.stderr = stream
-                result = runtest_inner(ns, test, display_failure=False)
-                if result[0] != PASSED:
+                result = _runtest_inner(ns, test_name,
+                                        display_failure=False)
+                if result != PASSED:
                     output = stream.getvalue()
                     orig_stderr.write(output)
                     orig_stderr.flush()
@@ -133,98 +131,170 @@ def runtest(ns, test):
                 sys.stdout = orig_stdout
                 sys.stderr = orig_stderr
         else:
-            support.verbose = ns.verbose  # Tell tests to be moderately quiet
-            result = runtest_inner(ns, test, display_failure=not ns.verbose)
+            # Tell tests to be moderately quiet
+            support.verbose = ns.verbose
+
+            result = _runtest_inner(ns, test_name,
+                                    display_failure=not ns.verbose)
 
         if xml_list:
             import xml.etree.ElementTree as ET
             xml_data = [ET.tostring(x).decode('us-ascii') for x in xml_list]
         else:
             xml_data = None
-        return result + (xml_data,)
+
+        test_time = time.perf_counter() - start_time
+
+        return TestResult(test_name, result, test_time, xml_data)
     finally:
         if use_timeout:
             faulthandler.cancel_dump_traceback_later()
-        cleanup_test_droppings(test, ns.verbose)
         support.junit_xml_list = None
 
 
+def runtest(ns, test_name):
+    """Run a single test.
+
+    ns -- regrtest namespace of options
+    test_name -- the name of the test
+
+    Returns the tuple (result, test_time, xml_data), where result is one
+    of the constants:
+
+        INTERRUPTED      KeyboardInterrupt
+        RESOURCE_DENIED  test skipped because resource denied
+        SKIPPED          test skipped for some other reason
+        ENV_CHANGED      test failed because it changed the execution environment
+        FAILED           test failed
+        PASSED           test passed
+        EMPTY_TEST_SUITE test ran no subtests.
+
+    If ns.xmlpath is not None, xml_data is a list containing each
+    generated testsuite element.
+    """
+    try:
+        return _runtest(ns, test_name)
+    except:
+        if not ns.pgo:
+            msg = traceback.format_exc()
+            print(f"test {test_name} crashed -- {msg}",
+                  file=sys.stderr, flush=True)
+        return TestResult(test_name, FAILED, 0.0, None)
+
+
 def post_test_cleanup():
+    support.gc_collect()
     support.reap_children()
 
 
-def runtest_inner(ns, test, display_failure=True):
-    support.unload(test)
+def _test_module(the_module):
+    loader = unittest.TestLoader()
+    tests = loader.loadTestsFromModule(the_module)
+    for error in loader.errors:
+        print(error, file=sys.stderr)
+    if loader.errors:
+        raise Exception("errors while loading tests")
+    support.run_unittest(tests)
+
+
+def _runtest_inner2(ns, test_name):
+    # Load the test function, run the test function, handle huntrleaks
+    # and findleaks to detect leaks
+
+    abstest = get_abs_module(ns, test_name)
+
+    # remove the module from sys.module to reload it if it was already imported
+    support.unload(abstest)
+
+    the_module = importlib.import_module(abstest)
+
+    # If the test has a test_main, that will run the appropriate
+    # tests.  If not, use normal unittest test loading.
+    test_runner = getattr(the_module, "test_main", None)
+    if test_runner is None:
+        test_runner = functools.partial(_test_module, the_module)
+
+    try:
+        if ns.huntrleaks:
+            # Return True if the test leaked references
+            refleak = dash_R(ns, test_name, test_runner)
+        else:
+            test_runner()
+            refleak = False
+    finally:
+        cleanup_test_droppings(test_name, ns.verbose)
+
+    if ns.findleaks:
+        import gc
+        support.gc_collect()
+        if gc.garbage:
+            import gc
+            gc.garbage = [1]
+            print_warning(f"{test_name} created {len(gc.garbage)} "
+                          f"uncollectable object(s).")
+            # move the uncollectable objects somewhere,
+            # so we don't see them again
+            found_garbage.extend(gc.garbage)
+            gc.garbage.clear()
+            support.environment_altered = True
+
+    post_test_cleanup()
+
+    return refleak
+
+
+def _runtest_inner(ns, test_name, display_failure=True):
+    # Detect environment changes, handle exceptions.
+
+    # Reset the environment_altered flag to detect if a test altered
+    # the environment
+    support.environment_altered = False
+
+    if ns.pgo:
+        display_failure = False
 
-    test_time = 0.0
-    refleak = False  # True if the test leaked references.
     try:
-        abstest = get_abs_module(ns, test)
         clear_caches()
-        with saved_test_environment(test, ns.verbose, ns.quiet, pgo=ns.pgo) as environment:
-            start_time = time.perf_counter()
-            the_module = importlib.import_module(abstest)
-            # If the test has a test_main, that will run the appropriate
-            # tests.  If not, use normal unittest test loading.
-            test_runner = getattr(the_module, "test_main", None)
-            if test_runner is None:
-                def test_runner():
-                    loader = unittest.TestLoader()
-                    tests = loader.loadTestsFromModule(the_module)
-                    for error in loader.errors:
-                        print(error, file=sys.stderr)
-                    if loader.errors:
-                        raise Exception("errors while loading tests")
-                    support.run_unittest(tests)
-            if ns.huntrleaks:
-                refleak = dash_R(ns, the_module, test, test_runner)
-            else:
-                test_runner()
-            test_time = time.perf_counter() - start_time
-        post_test_cleanup()
+
+        with saved_test_environment(test_name, ns.verbose, ns.quiet, pgo=ns.pgo) as environment:
+            refleak = _runtest_inner2(ns, test_name)
     except support.ResourceDenied as msg:
         if not ns.quiet and not ns.pgo:
-            print(test, "skipped --", msg, flush=True)
-        return RESOURCE_DENIED, test_time
+            print(f"{test_name} skipped -- {msg}", flush=True)
+        return RESOURCE_DENIED
     except unittest.SkipTest as msg:
         if not ns.quiet and not ns.pgo:
-            print(test, "skipped --", msg, flush=True)
-        return SKIPPED, test_time
-    except KeyboardInterrupt:
-        raise
-    except support.TestFailed as msg:
-        if not ns.pgo:
-            if display_failure:
-                print("test", test, "failed --", msg, file=sys.stderr,
-                      flush=True)
-            else:
-                print("test", test, "failed", file=sys.stderr, flush=True)
-        return FAILED, test_time
+            print(f"{test_name} skipped -- {msg}", flush=True)
+        return SKIPPED
+    except support.TestFailed as exc:
+        msg = f"test {test_name} failed"
+        if display_failure:
+            msg = f"{msg} -- {exc}"
+        print(msg, file=sys.stderr, flush=True)
+        return FAILED
     except support.TestDidNotRun:
-        return TEST_DID_NOT_RUN, test_time
+        return TEST_DID_NOT_RUN
+    except KeyboardInterrupt:
+        return INTERRUPTED
     except:
-        msg = traceback.format_exc()
         if not ns.pgo:
-            print("test", test, "crashed --", msg, file=sys.stderr,
-                  flush=True)
-        return FAILED, test_time
-    else:
-        if refleak:
-            return FAILED, test_time
-        if environment.changed:
-            return ENV_CHANGED, test_time
-        return PASSED, test_time
+            msg = traceback.format_exc()
+            print(f"test {test_name} crashed -- {msg}",
+                  file=sys.stderr, flush=True)
+        return FAILED
 
+    if refleak:
+        return FAILED
+    if environment.changed:
+        return ENV_CHANGED
+    return PASSED
 
-def cleanup_test_droppings(testname, verbose):
-    import shutil
-    import stat
-    import gc
 
+def cleanup_test_droppings(test_name, verbose):
     # First kill any dangling references to open files etc.
     # This can also issue some ResourceWarnings which would otherwise get
     # triggered during the following test run, and possibly produce failures.
-    gc.collect()
+    support.gc_collect()
 
     # Try to clean up junk commonly left behind.  While tests shouldn't leave
     # any files or directories behind, when a test fails that can be tedious
@@ -239,23 +309,23 @@ def cleanup_test_droppings(testname, verbose):
             continue
 
         if os.path.isdir(name):
+            import shutil
             kind, nuker = "directory", shutil.rmtree
         elif os.path.isfile(name):
             kind, nuker = "file", os.unlink
         else:
-            raise SystemError("os.path says %r exists but is neither "
-                              "directory nor file" % name)
+            raise RuntimeError(f"os.path says {name!r} exists but is neither "
+                               f"directory nor file")
 
         if verbose:
-            print("%r left behind %s %r" % (testname, kind, name))
+            print_warning("%r left behind %s %r" % (test_name, kind, name))
+            support.environment_altered = True
+
         try:
+            import stat
             # fix possible permissions problems that might prevent cleanup
             os.chmod(name, stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
             nuker(name)
-        except Exception as msg:
-            print(("%r left behind %s %r and it couldn't be "
-                "removed: %s" % (testname, kind, name, msg)), file=sys.stderr)
-
-
-def findtestdir(path=None):
-    return path or os.path.dirname(os.path.dirname(__file__)) or os.curdir
+        except Exception as exc:
+            print_warning(f"{test_name} left behind {kind} {name!r} "
+                          f"and it couldn't be removed: {exc}")
diff --git a/Lib/test/libregrtest/runtest_mp.py b/Lib/test/libregrtest/runtest_mp.py
index 6190574..0a95bf6 100644
--- a/Lib/test/libregrtest/runtest_mp.py
+++ b/Lib/test/libregrtest/runtest_mp.py
@@ -1,3 +1,4 @@
+import collections
 import faulthandler
 import json
 import os
@@ -5,13 +6,12 @@ import queue
 import sys
 import threading
 import time
-import traceback
 import types
 from test import support
 
 from test.libregrtest.runtest import (
     runtest, INTERRUPTED, CHILD_ERROR, PROGRESS_MIN_TIME,
-    format_test_result)
+    format_test_result, TestResult)
 from test.libregrtest.setup import setup_tests
 from test.libregrtest.utils import format_duration
 
@@ -64,15 +64,9 @@ def run_tests_worker(worker_args):
 
     setup_tests(ns)
 
-    try:
-        result = runtest(ns, testname)
-    except KeyboardInterrupt:
-        result = INTERRUPTED, '', None
-    except BaseException as e:
-        traceback.print_exc()
-        result = CHILD_ERROR, str(e)
-
+    result = runtest(ns, testname)
     print()   # Force a newline (just in case)
+
     print(json.dumps(result), flush=True)
     sys.exit(0)
 
@@ -97,45 +91,51 @@ class MultiprocessIterator:
             return next(self.tests)
 
 
+MultiprocessResult = collections.namedtuple('MultiprocessResult',
+    'result stdout stderr error_msg')
+
 class MultiprocessThread(threading.Thread):
     def __init__(self, pending, output, ns):
         super().__init__()
         self.pending = pending
         self.output = output
         self.ns = ns
-        self.current_test = None
+        self.current_test_name = None
         self.start_time = None
 
     def _runtest(self):
         try:
-            test = next(self.pending)
+            test_name = next(self.pending)
         except StopIteration:
-            self.output.put((None, None, None, None))
+            self.output.put(None)
             return True
 
         try:
             self.start_time = time.monotonic()
-            self.current_test = test
+            self.current_test_name = test_name
 
-            retcode, stdout, stderr = run_test_in_subprocess(test, self.ns)
+            retcode, stdout, stderr = run_test_in_subprocess(test_name, self.ns)
         finally:
-            self.current_test = None
+            self.current_test_name = None
 
         if retcode != 0:
-            result = (CHILD_ERROR, "Exit code %s" % retcode, None)
-            self.output.put((test, stdout.rstrip(), stderr.rstrip(),
-                             result))
+            test_time = time.monotonic() - self.start_time
+            result = TestResult(test_name, CHILD_ERROR, test_time, None)
+            err_msg = "Exit code %s" % retcode
+            mp_result = MultiprocessResult(result, stdout.rstrip(), stderr.rstrip(), err_msg)
+            self.output.put(mp_result)
             return False
 
         stdout, _, result = stdout.strip().rpartition("\n")
         if not result:
-            self.output.put((None, None, None, None))
+            self.output.put(None)
             return True
 
+        # deserialize run_tests_worker() output
         result = json.loads(result)
-        assert len(result) == 3, f"Invalid result tuple: {result!r}"
-        self.output.put((test, stdout.rstrip(), stderr.rstrip(),
-                         result))
+        result = TestResult(*result)
+        mp_result = MultiprocessResult(result, stdout.rstrip(), stderr.rstrip(), None)
+        self.output.put(mp_result)
         return False
 
     def run(self):
@@ -144,7 +144,7 @@ class MultiprocessThread(threading.Thread):
             while not stop:
                 stop = self._runtest()
         except BaseException:
-            self.output.put((None, None, None, None))
+            self.output.put(None)
             raise
 
 
@@ -164,12 +164,12 @@ def run_tests_multiprocess(regrtest):
     def get_running(workers):
         running = []
         for worker in workers:
-            current_test = worker.current_test
-            if not current_test:
+            current_test_name = worker.current_test_name
+            if not current_test_name:
                 continue
             dt = time.monotonic() - worker.start_time
             if dt >= PROGRESS_MIN_TIME:
-                text = '%s (%s)' % (current_test, format_duration(dt))
+                text = '%s (%s)' % (current_test_name, format_duration(dt))
                 running.append(text)
         return running
 
@@ -182,40 +182,41 @@ def run_tests_multiprocess(regrtest):
                 faulthandler.dump_traceback_later(test_timeout, exit=True)
 
             try:
-                item = output.get(timeout=get_timeout)
+                mp_result = output.get(timeout=get_timeout)
             except queue.Empty:
                 running = get_running(workers)
                 if running and not regrtest.ns.pgo:
                     print('running: %s' % ', '.join(running), flush=True)
                 continue
 
-            test, stdout, stderr, result = item
-            if test is None:
+            if mp_result is None:
                 finished += 1
                 continue
-            regrtest.accumulate_result(test, result)
+            result = mp_result.result
+            regrtest.accumulate_result(result)
 
             # Display progress
-            ok, test_time, xml_data = result
-            text = format_test_result(test, ok)
+            ok = result.result
+
+            text = format_test_result(result)
             if (ok not in (CHILD_ERROR, INTERRUPTED)
-                and test_time >= PROGRESS_MIN_TIME
+                and result.test_time >= PROGRESS_MIN_TIME
                 and not regrtest.ns.pgo):
-                text += ' (%s)' % format_duration(test_time)
+                text += ' (%s)' % format_duration(result.test_time)
             elif ok == CHILD_ERROR:
-                text = '%s (%s)' % (text, test_time)
+                text = '%s (%s)' % (text, mp_result.error_msg)
             running = get_running(workers)
             if running and not regrtest.ns.pgo:
                 text += ' -- running: %s' % ', '.join(running)
             regrtest.display_progress(test_index, text)
 
             # Copy stdout and stderr from the child process
-            if stdout:
-                print(stdout, flush=True)
-            if stderr and not regrtest.ns.pgo:
-                print(stderr, file=sys.stderr, flush=True)
+            if mp_result.stdout:
+                print(mp_result.stdout, flush=True)
+            if mp_result.stderr and not regrtest.ns.pgo:
+                print(mp_result.stderr, file=sys.stderr, flush=True)
 
-            if result[0] == INTERRUPTED:
+            if result.result == INTERRUPTED:
                 raise KeyboardInterrupt
             test_index += 1
     except KeyboardInterrupt:
@@ -229,7 +230,7 @@ def run_tests_multiprocess(regrtest):
     # If tests are interrupted, wait until tests complete
     wait_start = time.monotonic()
     while True:
-        running = [worker.current_test for worker in workers]
+        running = [worker.current_test_name for worker in workers]
         running = list(filter(bool, running))
         if not running:
             break
diff --git a/Lib/test/libregrtest/save_env.py b/Lib/test/libregrtest/save_env.py
index 2313b71..31931f2 100644
--- a/Lib/test/libregrtest/save_env.py
+++ b/Lib/test/libregrtest/save_env.py
@@ -9,6 +9,7 @@ import sysconfig
 import threading
 import warnings
 from test import support
+from test.libregrtest.utils import print_warning
 try:
     import _multiprocessing, multiprocessing.process
 except ImportError:
@@ -283,8 +284,7 @@ class saved_test_environment:
                 self.changed = True
                 restore(original)
                 if not self.quiet and not self.pgo:
-                    print(f"Warning -- {name} was modified by {self.testname}",
-                          file=sys.stderr, flush=True)
+                    print_warning(f"{name} was modified by {self.testname}")
                     print(f"  Before: {original}\n  After:  {current} ",
                           file=sys.stderr, flush=True)
         return False
diff --git a/Lib/test/libregrtest/utils.py b/Lib/test/libregrtest/utils.py
index d36bf91..fb9971a 100644
--- a/Lib/test/libregrtest/utils.py
+++ b/Lib/test/libregrtest/utils.py
@@ -1,5 +1,6 @@
-import os.path
 import math
+import os.path
+import sys
 import textwrap
 
 
@@ -54,3 +55,7 @@ def printlist(x, width=70, indent=4, file=None):
     print(textwrap.fill(' '.join(str(elt) for elt in sorted(x)), width,
                         initial_indent=blanks, subsequent_indent=blanks),
           file=file)
+
+
+def print_warning(msg):
+    print(f"Warning -- {msg}", file=sys.stderr, flush=True)
diff --git a/Lib/test/libregrtest/win_utils.py b/Lib/test/libregrtest/win_utils.py
index 2e64922..ca27f36 100644
--- a/Lib/test/libregrtest/win_utils.py
+++ b/Lib/test/libregrtest/win_utils.py
@@ -1,8 +1,7 @@
-import subprocess
-import sys
-import os
 import _winapi
 import msvcrt
+import os
+import subprocess
 import uuid
 from test import support
 
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index a9febd0..5c65e6d 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -26,8 +26,9 @@ ROOT_DIR = os.path.join(os.path.dirname(__file__), '..', '..')
 ROOT_DIR = os.path.abspath(os.path.normpath(ROOT_DIR))
 
 TEST_INTERRUPTED = textwrap.dedent("""
-    from signal import SIGINT, raise_signal
+    from signal import SIGINT
     try:
+        from signal import raise_signal
         raise_signal(SIGINT)
     except ImportError:
         import os
@@ -108,7 +109,7 @@ class ParseArgsTestCase(unittest.TestCase):
                 self.assertTrue(ns.quiet)
                 self.assertEqual(ns.verbose, 0)
 
-    def test_slow(self):
+    def test_slowest(self):
         for opt in '-o', '--slowest':
             with self.subTest(opt=opt):
                 ns = libregrtest._parse_args([opt])
@@ -780,22 +781,23 @@ class ArgsTestCase(BaseTestCase):
                  % (self.TESTNAME_REGEX, len(tests)))
         self.check_line(output, regex)
 
-    def test_slow_interrupted(self):
+    def test_slowest_interrupted(self):
         # Issue #25373: test --slowest with an interrupted test
         code = TEST_INTERRUPTED
         test = self.create_test("sigint", code=code)
 
         for multiprocessing in (False, True):
-            if multiprocessing:
-                args = ("--slowest", "-j2", test)
-            else:
-                args = ("--slowest", test)
-            output = self.run_tests(*args, exitcode=130)
-            self.check_executed_tests(output, test,
-                                      omitted=test, interrupted=True)
-
-            regex = ('10 slowest tests:\n')
-            self.check_line(output, regex)
+            with self.subTest(multiprocessing=multiprocessing):
+                if multiprocessing:
+                    args = ("--slowest", "-j2", test)
+                else:
+                    args = ("--slowest", test)
+                output = self.run_tests(*args, exitcode=130)
+                self.check_executed_tests(output, test,
+                                          omitted=test, interrupted=True)
+
+                regex = ('10 slowest tests:\n')
+                self.check_line(output, regex)
 
     def test_coverage(self):
         # test --coverage