make the test separate

Author: nsarang

pandas/tests/reshape/merge/test_merge.py

@@ -2149,8 +2149,6 @@ def test_merge_index_types(index):
         (None, None, None, True, True, "B"),
         (None, ["outer", "inner"], None, False, True, "B"),
         (None, None, ["outer", "inner"], True, False, "B"),
-        (["outer", "inner"], None, None, False, False, ("B", "C")),
-        (None, None, ["outer", "inner"], True, False, ("B", "C")),
         (["outer", "inner"], None, None, False, False, None),
         (None, None, None, True, True, None),
         (None, ["outer", "inner"], None, False, True, None),
@@ -2169,7 +2167,7 @@ def test_merge_series(on, left_on, right_on, left_index, right_index, nm):
         name=nm,
     )
     expected = DataFrame(
-        {"A": [2, 4], nm: [1, 3]},
+        {"A": [2, 4], "B": [1, 3]},
         index=MultiIndex.from_product([["a", "b"], [1]], names=["outer", "inner"]),
     )
     if nm is not None:
@@ -2197,6 +2195,39 @@ def test_merge_series(on, left_on, right_on, left_index, right_index, nm):
             )
 
 
+@pytest.mark.parametrize(
+    "on,left_on,right_on,left_index,right_index,name",
+    [
+        (["outer", "inner"], None, None, False, False, ("B", "C")),
+        (None, None, ["outer", "inner"], True, False, ("B", "C")),
+    ],
+)
+def test_merge_series_multilevel(on, left_on, right_on, left_index, right_index, name):
+    a = DataFrame(
+        {"A": [1, 2, 3, 4]},
+        index=MultiIndex.from_product([["a", "b"], [0, 1]], names=["outer", "inner"]),
+    )
+    b = Series(
+        [1, 2, 3, 4],
+        index=MultiIndex.from_product([["a", "b"], [1, 2]], names=["outer", "inner"]),
+        name=name,
+    )
+    expected = DataFrame(
+        {"A": [2, 4], name: [1, 3]},
+        index=MultiIndex.from_product([["a", "b"], [1]], names=["outer", "inner"]),
+    )
+    result = merge(
+        a,
+        b,
+        on=on,
+        left_on=left_on,
+        right_on=right_on,
+        left_index=left_index,
+        right_index=right_index,
+    )
+    tm.assert_frame_equal(result, expected)
+
+
 @pytest.mark.parametrize(
     "col1, col2, kwargs, expected_cols",
     [