revert playwright browser install change, address review findings

Author: bckohan

conftest.py

@@ -66,28 +66,9 @@ def _install_playwright_browsers() -> None:
     subprocess.run(cmd, check=True)
 
 
-def _playwright_chromium_installed() -> bool:
-    """Quick check if Playwright chromium browsers are already installed."""
-    import os
-
-    # Check the default Playwright browsers cache location
-    browsers_path = os.environ.get(
-        "PLAYWRIGHT_BROWSERS_PATH",
-        os.path.join(os.path.expanduser("~"), ".cache", "ms-playwright"),
-    )
-    return os.path.isdir(browsers_path) and any(
-        entry.startswith("chromium") for entry in os.listdir(browsers_path)
-    )
-
-
 def pytest_collection_modifyitems(config: pytest.Config, items: list[pytest.Item]) -> None:
     any_ui = any(item.get_closest_marker("ui") is not None for item in items)
 
     if any_ui and not getattr(config, "_did_install_playwright", False):
         setattr(config, "_did_install_playwright", True)
-        if not _playwright_chromium_installed():
-            # Browsers not available: deselect UI tests so the rest of the suite can run.
-            # To run UI tests, install Playwright browsers first:
-            #   playwright install chromium
-            config.hook.pytest_deselected(items=[i for i in items if i.get_closest_marker("ui")])
-            items[:] = [i for i in items if i.get_closest_marker("ui") is None]
+        _install_playwright_browsers()

src/polymorphic/tests/test_missing_coverage.py

@@ -321,28 +321,6 @@ class FakeConnection:
             results = list(qs)
             assert len(results) >= 2
 
-    def test_max_chunk_zero_uses_default(self):
-        """Test the code path where max_query_params=0 → use Polymorphic_QuerySet_objects_per_request."""
-        from unittest.mock import patch, PropertyMock
-
-        import django.db.backends.base.features as features_module
-
-        Model2A.objects.create(field1="mq_zero_a")
-        Model2B.objects.create(field1="mq_zero_b", field2="B2")
-
-        qs = Model2A.objects.all()
-
-        # Patch the connection features to return 0 for max_query_params
-        with patch("django.db.connections") as mock_connections:
-            mock_features = type("MockFeatures", (), {"max_query_params": 0})()
-            mock_connection = type("MockConn", (), {"features": mock_features})()
-            mock_connections.__getitem__ = lambda self, key: mock_connection
-
-            # Can't easily use this - instead verify the existing behavior
-            # The default is 2000 - just verify it works
-            results = list(qs)
-            assert len(results) >= 2
-
 
 # ===========================================================================
 # query.py - non_polymorphic() False branch of issubclass check (lines 216->218)
@@ -1203,16 +1181,20 @@ def test_unbound_formset_ct_as_int(self):
 
 
 # ===========================================================================
-# formsets/models.py - model from queryset_data (line 255)
+# formsets/models.py - per-row model selection for an unbound formset
 # ===========================================================================
 
 
 class TestFormsetModelFromQuerysetData(TestCase):
-    """Test unbound formset where model comes from queryset_data."""
+    """Test that an unbound formset built from a mixed-type queryset selects the
+    correct child model for each row."""
 
     def test_model_from_queryset_data(self):
         """
-        Line 255: When no instance or initial, model comes from queryset_data[i].__class__.
+        Each initial form is bound to its queryset object's real concrete class
+        (the ``defaults["instance"]`` branch in ``_construct_form``), so a formset
+        over a mixed Model2A/Model2B queryset produces one correctly-typed form
+        per row.
         """
         obj_a = Model2A.objects.create(field1="qs_data_a")
         obj_b = Model2B.objects.create(field1="qs_data_b", field2="B2")
@@ -1234,10 +1216,9 @@ def test_model_from_queryset_data(self):
         forms = formset.forms
         # The form types come from the queryset_data items
         assert len(forms) == 2
-        # At least one form for each type
-        field1s = {form.instance.__class__.__name__ for form in forms if form.instance.pk}
-        # queryset_data drives the model for each form
-        assert len(forms) == 2
+        # queryset_data drives the model for each form: one Model2A and one Model2B
+        form_models = {form.instance.__class__ for form in forms if form.instance.pk}
+        assert form_models == {Model2A, Model2B}
 
 
 # ===========================================================================
@@ -1896,5 +1877,7 @@ def patched_is_valid(self_inner, *args, **kwargs):
 
         with mock.patch.object(drf_serializers.Serializer, "is_valid", patched_is_valid):
             result = s.is_valid()
-            # Result depends on child validation (child is valid, so True)
-            # But _validated_data was deleted before the check, so branch 98->101 executes
+            # _validated_data was deleted before the check, so branch 98->101 executes:
+            # the child's _validated_data is NOT merged into the parent, but no
+            # AttributeError is raised and is_valid still returns True (parent + child valid).
+            assert result is True