Fix: Issue #1140

changelog/1140.bugfix.rst

@@ -0,0 +1 @@
+Fixed duplicate ``pytest_collectreport`` calls (one per worker) for the same collection error when a test module fails to collect under ``-n``.

src/xdist/dsession.py

@@ -55,7 +55,7 @@ def __init__(self, config: pytest.Config) -> None:
         self.maxfail: int = config.getvalue("maxfail")
         self.queue: Queue[tuple[str, dict[str, Any]]] = Queue()
         self._session: pytest.Session | None = None
-        self._failed_collection_errors: dict[object, bool] = {}
+        self._failed_collection_errors: dict[str, bool] = {}
         self._active_nodes: set[WorkerController] = set()
         self._failed_nodes_count = 0
         self._max_worker_restart = get_default_max_worker_restart(self.config)
@@ -409,9 +409,11 @@ def _failed_worker_collectreport(
         rep: pytest.CollectReport | pytest.TestReport,
     ) -> None:
         # Check we haven't already seen this report (from
-        # another worker).
-        if rep.longrepr not in self._failed_collection_errors:
-            self._failed_collection_errors[rep.longrepr] = True
+        # another worker). Keyed by nodeid, not longrepr: pytest's
+        # longrepr classes are `eq=False` dataclasses, so identical
+        # errors from different workers never compare equal.
+        if rep.nodeid not in self._failed_collection_errors:
+            self._failed_collection_errors[rep.nodeid] = True
             self.config.hook.pytest_collectreport(report=rep)
             self._handlefailures(rep)
 

testing/acceptance_test.py

@@ -1699,6 +1699,20 @@ def test_collection_crash(pytester: pytest.Pytester) -> None:
     )
 
 
+def test_collection_crash_reported_once(pytester: pytest.Pytester) -> None:
+    """A collection error must be reported only once, regardless of how
+    many workers collected the failing module (#1140)."""
+    p1 = pytester.makepyfile(
+        """
+        assert 0
+    """
+    )
+    result = pytester.runpytest(p1, "-n2")
+    assert result.ret == 1
+    assert result.stdout.lines.count("E   assert 0") == 1
+    result.stdout.fnmatch_lines(["*= 1 error in *"])
+
+
 def test_dist_in_addopts(pytester: pytest.Pytester) -> None:
     """Users can set a default distribution in the configuration file (#789)."""
     pytester.makepyfile(