TST: add regression test for DataFrame.mean(axis=1) with nullable Int64 dtype (GH#36585)

Author: Tunahanyrd

pandas/tests/frame/test_reductions.py

@@ -2170,3 +2170,22 @@ def test_numeric_ea_axis_1(method, skipna, min_count, any_numeric_ea_dtype):
     if method not in ("idxmax", "idxmin"):
         expected = expected.astype(expected_dtype)
     tm.assert_series_equal(result, expected)
+
+def test_mean_nullable_int_axis_1():
+    """
+    Test DataFrame.mean(axis=1) with nullable Int64 dtype.
+
+    Ensures correct results with skipna=True and skipna=False.
+    """
+    df = pd.DataFrame({
+    "a": [1, 2, 3, 4],
+    "b": pd.Series([1, 2, 4, None], dtype=pd.Int64Dtype())
+    })
+
+    result = df.mean(axis=1, skipna=True)
+    expected = pd.Series([1.0, 2.0, 3.5, 4.0], dtype="Float64")
+    pd.testing.assert_series_equal(result, expected)
+    
+    result = df.mean(axis=1, skipna=False)
+    expected = pd.Series([1.0, 2.0, 3.5, pd.NA], dtype="Float64")
+    pd.testing.assert_series_equal(result, expected)