TST: add OP test, use fixture in the index test

Author: AlexKirko

pandas/tests/indexes/test_common.py

@@ -398,13 +398,16 @@ def test_astype_preserves_name(self, index, dtype, copy):
             assert result.name == index.name
 
 
-@pytest.mark.parametrize("exp_arr, sort", [([0, 1, 4, 3], False), ([0, 1, 3, 4], True)])
+@pytest.mark.parametrize("arr", [[0, 1, 4, 3]])
 @pytest.mark.parametrize("dtype", ["int8", "int16", "int32", "int64"])
-def test_union_index_no_sort(exp_arr, sort, dtype):
+def test_union_index_no_sort(arr, sort, dtype):
     # GH 35092. Check that we don't sort with sort=False
-    ind1 = Index([0, 1], dtype=dtype)
-    ind2 = Index([4, 3], dtype=dtype)
+    ind1 = Index(arr[:2], dtype=dtype)
+    ind2 = Index(arr[2:], dtype=dtype)
 
-    expected = Index(exp_arr, dtype=dtype)
+    # sort is None indicates that we sort the combined index
+    if sort is None:
+        arr.sort()
+    expected = Index(arr, dtype=dtype)
     result = union_indexes([ind1, ind2], sort=sort)
     tm.assert_index_equal(result, expected)

pandas/tests/reshape/test_concat.py

@@ -2857,3 +2857,17 @@ def test_concat_frame_axis0_extension_dtypes():
     result = pd.concat([df2, df1], ignore_index=True)
     expected = pd.DataFrame({"a": [4, 5, 6, 1, 2, 3]}, dtype="Int64")
     tm.assert_frame_equal(result, expected)
+
+
+@pytest.mark.parametrize("sort", [True, False])
+def test_append_sort(sort):
+    # GH 35092. Check that DataFrame.append respects the sort argument.
+    df1 = pd.DataFrame(data={0: [1,2], 1: [3,4]})
+    df2 = pd.DataFrame(data={3: [1,2], 2: [3,4]})
+    cols = list(df1.columns) + list(df2.columns)
+    if sort:
+        cols.sort()
+
+    result = df1.append(df2, sort=sort).columns
+    expected = type(result)(cols)
+    tm.assert_index_equal(result, expected)