Fix #339: isolate automatic Git maintenance in disposable D5/C6 fixtures

tests/test_d5_c6_git_isolation.py

@@ -0,0 +1,120 @@
+"""Real-Git lifecycle regression for the disposable D5/C6 protocol fixtures.
+
+The controlled task is eligible after one commit. Foreground maintenance makes
+this a deterministic child-launch test, not a probabilistic cleanup-race test.
+No real repository configuration, production checker, or subprocess is mocked.
+"""
+import json
+import os
+from pathlib import Path
+import subprocess
+import sys
+import tempfile
+import unittest
+
+
+ROOT = Path(__file__).resolve().parents[1]
+FIXTURE = ROOT / 'tests/test_d5_c6_workflows.py'
+
+
+def trace_environment(trace):
+    env = {key: value for key, value in os.environ.items()
+           if not key.startswith('GIT_')}
+    settings = [
+        ('maintenance.auto', 'true'),
+        ('maintenance.autoDetach', 'false'),
+        ('maintenance.gc.enabled', 'false'),
+        ('maintenance.loose-objects.enabled', 'true'),
+        ('maintenance.loose-objects.auto', '-1'),
+    ]
+    env.update(GIT_CONFIG_NOSYSTEM='1', GIT_CONFIG_GLOBAL=os.devnull,
+               GIT_TRACE2_EVENT=str(trace.resolve()),
+               GIT_CONFIG_COUNT=str(len(settings)))
+    for index, (key, value) in enumerate(settings):
+        env['GIT_CONFIG_KEY_' + str(index)] = key
+        env['GIT_CONFIG_VALUE_' + str(index)] = value
+    return env
+
+
+def read_events(trace):
+    return [json.loads(line) for line in trace.read_text().splitlines() if line]
+
+
+def child_commands(events):
+    return [event.get('argv', []) for event in events
+            if event.get('event') == 'child_start']
+
+
+def maintenance_commands(events):
+    return [argv for argv in child_commands(events)
+            if 'maintenance' in argv and '--auto' in argv]
+
+
+def trace_fixture(fixture, folder, family, behavior='valid'):
+    """Execute the actual fixture function in an isolated child interpreter."""
+    trace = folder / 'git-trace.jsonl'
+    env = trace_environment(trace)
+    env['WORKFLOW_SOURCE_ROOT'] = str(fixture.resolve().parents[1])
+    driver = '''import importlib.util,json,subprocess,sys
+from pathlib import Path
+p=Path(sys.argv[1])
+spec=importlib.util.spec_from_file_location('fixture_under_test',p)
+m=importlib.util.module_from_spec(spec)
+spec.loader.exec_module(m)
+def auto():
+    return subprocess.check_output(['git','config','--bool','--get','maintenance.auto'],text=True).strip()
+before=auto()
+r=m.run_fixture(sys.argv[2],sys.argv[3])
+after=auto()
+print(json.dumps({'before':before,'after':after,'returncode':r.returncode,
+                  'stdout':r.stdout.decode(),'stderr':r.stderr.decode()}))
+'''
+    flags = ['-B', '-O', '-S'] if sys.flags.optimize else ['-B', '-S']
+    result = subprocess.run([sys.executable, *flags, '-c', driver,
+                             str(fixture.resolve()), family, behavior],
+                            env=env, capture_output=True, timeout=60)
+    (folder / 'driver.stdout').write_bytes(result.stdout)
+    (folder / 'driver.stderr').write_bytes(result.stderr)
+    (folder / 'driver.exit').write_text(str(result.returncode) + '\n')
+    return result, read_events(trace)
+
+
+class GitFixtureIsolationTests(unittest.TestCase):
+    def test_actual_fixtures_never_launch_automatic_maintenance(self):
+        for family in ('d5', 'palm', 'factorial'):
+            with self.subTest(family=family), tempfile.TemporaryDirectory() as td:
+                result, events = trace_fixture(FIXTURE, Path(td), family)
+                self.assertEqual(result.returncode, 0, result.stderr.decode())
+                self.assertEqual(result.stderr, b'')
+                report = json.loads(result.stdout)
+                self.assertEqual(report['returncode'], 0, report)
+                self.assertEqual(report['stderr'], '')
+                self.assertEqual((report['before'], report['after']), ('true', 'true'))
+                commits = [event for event in events if event.get('event') == 'start'
+                           and 'commit' in event.get('argv', [])]
+                self.assertEqual(len(commits), 1, 'trace must observe the real fixture commit')
+                self.assertEqual(maintenance_commands(events), [],
+                                 'fixture commit launched automatic maintenance before cleanup')
+
+    def test_trace_detects_eligible_maintenance_in_positive_control(self):
+        with tempfile.TemporaryDirectory() as td:
+            folder = Path(td)
+            root = folder / 'positive-control'
+            root.mkdir()
+            trace = folder / 'positive-trace.jsonl'
+            env = trace_environment(trace)
+            (root / 'payload').write_bytes(b'synthetic positive control\n')
+            for command in (['git', 'init', '-q'], ['git', 'add', '.'],
+                            ['git', '-c', 'user.name=Protocol Fixture',
+                             '-c', 'user.email=fixture@example.invalid',
+                             '-c', 'commit.gpgsign=false', 'commit', '-qm', 'positive control']):
+                subprocess.run(command, cwd=root, env=env, check=True, capture_output=True, timeout=30)
+            events = read_events(trace)
+            self.assertEqual(len(maintenance_commands(events)), 1,
+                             'positive control must start automatic maintenance')
+            self.assertTrue(any('pack-objects' in argv for argv in child_commands(events)),
+                            'forced loose-object task must actually run')
+
+
+if __name__ == '__main__':
+    unittest.main()

tests/test_d5_c6_workflows.py

@@ -170,9 +170,12 @@ def run_fixture(family, behavior='valid', target=None, mode=0):
             shutil.copyfile(ROOT / HELPER, root / HELPER)
         env = dict(os.environ, PYTHONDONTWRITEBYTECODE='1', PYTHONPATH='')
         env.pop('PYTHONOPTIMIZE', None)
+        # A disposable repository must not leave detached maintenance writing
+        # into .git after this fixture starts cleanup (Math-#339).
         for cmd in (['git', 'init', '-q'], ['git', 'add', '.'],
                     ['git', '-c', 'user.name=Protocol Fixture', '-c', 'user.email=fixture@example.invalid',
-                     '-c', 'commit.gpgsign=false', 'commit', '-qm', 'synthetic test sources']):
+                     '-c', 'commit.gpgsign=false', '-c', 'maintenance.auto=false',
+                     'commit', '-qm', 'synthetic test sources']):
             subprocess.run(cmd, cwd=root, env=env, check=True, capture_output=True)
         if behavior == 'bad_manifest':
             manifest['files'][0]['sha256']='0'*64