[ArrayManager] TST: include subset of ArrayManager tests in all CI builds

ci/run_tests.sh

@@ -29,3 +29,8 @@ fi
 
 echo $PYTEST_CMD
 sh -c "$PYTEST_CMD"
+
+PYTEST_AM_CMD="PANDAS_DATA_MANAGER=array pytest -m \"$PATTERN and arraymanager\" -n $PYTEST_WORKERS  --dist=loadfile -s --strict-markers --durations=30 --junitxml=test-data.xml $TEST_ARGS $COVERAGE pandas"
+
+echo $PYTEST_AM_CMD
+sh -c "$PYTEST_AM_CMD"

pandas/conftest.py

@@ -85,6 +85,9 @@ def pytest_configure(config):
     config.addinivalue_line(
         "markers", "arm_slow: mark a test as slow for arm64 architecture"
     )
+    config.addinivalue_line(
+        "markers", "arraymanager: mark a test to run with ArrayManager enabled"
+    )
 
 
 def pytest_addoption(parser):
@@ -121,6 +124,13 @@ def pytest_runtest_setup(item):
         pytest.skip("skipping high memory test since --run-high-memory was not set")
 
 
+def pytest_collection_modifyitems(items):
+    for item in items:
+        # mark all tests in the pandas/tests/frame directory with "arraymanager"
+        if "/frame/" in item.nodeid:
+            item.add_marker(pytest.mark.arraymanager)
+
+
 # Hypothesis
 hypothesis.settings.register_profile(
     "ci",

pandas/tests/frame/indexing/test_setitem.py

@@ -926,7 +926,9 @@ def test_setitem_duplicate_columns_not_inplace(self):
         tm.assert_frame_equal(df_view, df_copy)
         tm.assert_frame_equal(df, expected)
 
-    @pytest.mark.parametrize("value", [1, np.array([[1], [1]]), [[1], [1]]])
+    @pytest.mark.parametrize(
+        "value", [1, np.array([[1], [1]], dtype="int64"), [[1], [1]]]
+    )
     def test_setitem_same_dtype_not_inplace(self, value, using_array_manager, request):
         # GH#39510
         if not using_array_manager:

pandas/tests/frame/test_reductions.py

@@ -382,7 +382,8 @@ def kurt(x):
             pass
 
     # TODO: Ensure warning isn't emitted in the first place
-    @pytest.mark.filterwarnings("ignore:All-NaN:RuntimeWarning")
+    # ignore mean of empty slice and all-NaN
+    @pytest.mark.filterwarnings("ignore::RuntimeWarning")
     def test_median(self, float_frame_with_na, int_frame):
         def wrapper(x):
             if isna(x).any():

pandas/tests/frame/test_stack_unstack.py

@@ -905,7 +905,7 @@ def test_unstack_nan_index3(self, using_array_manager):
         if using_array_manager:
             # INFO(ArrayManager) with ArrayManager preserve dtype where possible
             cols = right.columns[[1, 2, 3, 5]]
-            right[cols] = right[cols].astype("int64")
+            right[cols] = right[cols].astype(df["C"].dtype)
         tm.assert_frame_equal(left, right)
 
     def test_unstack_nan_index4(self):