add xdist, auto, group by test file

pyproject.toml

@@ -160,6 +160,7 @@ testing = [
     "pytest-pretty>=1.1.0",
     "pytest>=8.3.5",
     "pytest-rerunfailures>=15.1",
+    "pytest-xdist",
     "tensorstore>=0.1.32",
     "virtualenv>=20.17",
     "xarray>=0.16.2",
@@ -250,6 +251,7 @@ testing = [
     "pytest-pretty>=1.1.0",
     "pytest>=8.3.5",
     "pytest-rerunfailures>=15.1",
+    "pytest-xdist",
     "tensorstore>=0.1.32",
     "virtualenv>=20.17",
     "xarray>=0.16.2",

src/napari/_qt/_tests/test_app.py

@@ -38,6 +38,11 @@ def get_app_id():
 
 def test_run_outside_ipython(make_napari_viewer, qapp, monkeypatch):
     """Test that we don't incorrectly give ipython the event loop."""
+    # Mock the IPython module to avoid side effects from other tests
+    # when running with pytest-xdist
+    import sys
+    monkeypatch.setitem(sys.modules, 'IPython', None)
+
     assert not _ipython_has_eventloop()
     v1 = make_napari_viewer()
     assert not _ipython_has_eventloop()

src/napari/_tests/test_viewer.py

@@ -28,7 +28,7 @@ def _get_provider_actions(type_):
                 superclass
             ).values()
         )
-    return actions
+    return sorted(actions, key=lambda action: action.__name__)
 
 
 def _assert_shortcuts_exist_for_each_action(type_):

src/napari/conftest.py

@@ -247,7 +247,15 @@ def _auto_shutdown_dask_threadworkers():
     We don't assert the number of threads in unchanged as other things
     modify the number of threads.
     """
-    assert dask.threaded.default_pool is None
+    # Reset pool regardless of initial state (handles xdist case)
+    if dask.threaded.default_pool is not None:
+        if isinstance(dask.threaded.default_pool, ThreadPool):
+            dask.threaded.default_pool.close()
+            dask.threaded.default_pool.join()
+        else:
+            dask.threaded.default_pool.shutdown()
+        dask.threaded.default_pool = None
+
     try:
         yield
     finally:

tox.ini

@@ -107,9 +107,9 @@ indexserver =
 commands =
     cov: coverage run --parallel-mode \
     !cov: python \
-        -m pytest {env:PYTEST_PATH:} --color=yes --basetemp={envtmpdir} \
+        -m pytest -n logical --dist loadfile --reruns 3 --reruns-delay 3 \
+        {env:PYTEST_PATH:} --color=yes --basetemp={envtmpdir} \
         --ignore tools --maxfail=5 --json-report \
-    linux: --pystack-threshold=60 --pystack-args="--native-all" \
         --json-report-file={toxinidir}/report-{envname}.json {posargs} \
         --save-leaked-object-graph --import-mode=importlib