- fixed isolation module not handling pytest.Collector if returned

  by Module.collect();

src/slipcover/isolate.py

@@ -1,5 +1,4 @@
 import pytest
-import sys
 
 
 class IsolateItem(pytest.Item):
@@ -22,15 +21,23 @@ def run_forked(self):
         def runforked():
             module = pytest.Module.from_parent(parent=self.parent, path=self.path)
             reports = list()
-            for it in module.collect():
-                reports.extend(ptf.forked_run_report(it))
-            return marshal.dumps([self.config.hook.pytest_report_to_serializable(report=r) for r in reports])
+
+            def collect_and_run(collector):
+                for it in collector.collect():
+                    if isinstance(it, pytest.Collector):
+                        collect_and_run(it)
+                    else:
+                        reports.extend(ptf.forked_run_report(it))
+
+            collect_and_run(module)
+
+            return marshal.dumps([self.config.hook.pytest_report_to_serializable(config=self.config, report=r) for r in reports])
 
         ff = py.process.ForkedFunc(runforked)
         result = ff.waitfinish()
 
         if result.retval is not None:
-            reports = [self.config.hook.pytest_report_from_serializable(data=r) for r in marshal.loads(result.retval)]
+            reports = [self.config.hook.pytest_report_from_serializable(config=self.config, data=r) for r in marshal.loads(result.retval)]
         else:
             reports = [ptf.report_process_crash(self, result)]
 
@@ -64,4 +71,5 @@ def pytest_runtestloop(self, session):
 
 
 if __name__ == "__main__":
+    import sys
     sys.exit(pytest.main(sys.argv[1:], plugins=[IsolatePlugin()]))

tests/test_isolate.py

@@ -186,3 +186,29 @@ def test_foo():
         # can't capture coverage if the process gets killed
         if not (p == failing and fail_kind == 'kill'):
             assert str(p) in cov['files']
+
+
+def test_isolate_module_yields_collector(tmp_path, monkeypatch):
+    # A pytest.Collector.collect()'s return value may include not only pytest.Item,
+    # but also pytest.Collector.
+    #
+    # Here we test for this by including a class within the test module:
+    # when the module is being collected, pytest.Module.collect() will include
+    # a pytest.Class collector to actually collect items from within the class.
+
+    out = tmp_path / "out.json"
+
+    monkeypatch.chdir(tmp_path)
+    tests_dir = Path('tests')
+    tests_dir.mkdir()
+
+    test = seq2p(tests_dir, 1)
+    test.write_text("""\
+class TestClass:
+    def test_foo(self):
+        assert True
+""")
+
+    p = subprocess.run([sys.executable, '-m', 'slipcover', '--json', '--out', str(out),
+                                        '-m', 'slipcover.isolate', tests_dir], check=False)
+    assert p.returncode == pytest.ExitCode.OK