TST: flesh out EA setitem tests (#39034)

Author: jbrockmendel

pandas/tests/extension/base/setitem.py

@@ -8,6 +8,35 @@
 
 
 class BaseSetitemTests(BaseExtensionTests):
+    @pytest.fixture(
+        params=[
+            lambda x: x.index,
+            lambda x: list(x.index),
+            lambda x: slice(None),
+            lambda x: slice(0, len(x)),
+            lambda x: range(len(x)),
+            lambda x: list(range(len(x))),
+            lambda x: np.ones(len(x), dtype=bool),
+        ],
+        ids=[
+            "index",
+            "list[index]",
+            "null_slice",
+            "full_slice",
+            "range",
+            "list(range)",
+            "mask",
+        ],
+    )
+    def full_indexer(self, request):
+        """
+        Fixture for an indexer to pass to obj.loc to get/set the full length of the
+        object.
+
+        In some cases, assumes that obj.index is the default RangeIndex.
+        """
+        return request.param
+
     def test_setitem_scalar_series(self, data, box_in_series):
         if box_in_series:
             data = pd.Series(data)
@@ -305,30 +334,20 @@ def test_setitem_preserves_views(self, data):
         assert view1[0] == data[1]
         assert view2[0] == data[1]
 
-    def test_setitem_dataframe_column_with_index(self, data):
+    def test_setitem_with_expansion_dataframe_column(self, data, full_indexer):
         # https://github.com/pandas-dev/pandas/issues/32395
         df = expected = pd.DataFrame({"data": pd.Series(data)})
         result = pd.DataFrame(index=df.index)
-        result.loc[df.index, "data"] = df["data"]
-        self.assert_frame_equal(result, expected)
 
-    def test_setitem_dataframe_column_without_index(self, data):
-        # https://github.com/pandas-dev/pandas/issues/32395
-        df = expected = pd.DataFrame({"data": pd.Series(data)})
-        result = pd.DataFrame(index=df.index)
-        result.loc[:, "data"] = df["data"]
+        key = full_indexer(df)
+        result.loc[key, "data"] = df["data"]
         self.assert_frame_equal(result, expected)
 
-    def test_setitem_series_with_index(self, data):
+    def test_setitem_series(self, data, full_indexer):
         # https://github.com/pandas-dev/pandas/issues/32395
         ser = expected = pd.Series(data, name="data")
         result = pd.Series(index=ser.index, dtype=object, name="data")
-        result.loc[ser.index] = ser
-        self.assert_series_equal(result, expected)
 
-    def test_setitem_series_without_index(self, data):
-        # https://github.com/pandas-dev/pandas/issues/32395
-        ser = expected = pd.Series(data, name="data")
-        result = pd.Series(index=ser.index, dtype=object, name="data")
-        result.loc[:] = ser
+        key = full_indexer(ser)
+        result.loc[key] = ser
         self.assert_series_equal(result, expected)