TST: Add test for complex categories GH#16399 (pandas-dev#53551)

Signed-off-by: Liang Yan <[email protected]>

Author: liang3zy22

pandas/tests/dtypes/test_dtypes.py

@@ -1175,6 +1175,15 @@ def test_cast_string_to_complex():
     tm.assert_frame_equal(result, expected)
 
 
+def test_categorical_complex():
+    result = Categorical([1, 2 + 2j])
+    expected = Categorical([1.0 + 0.0j, 2.0 + 2.0j])
+    tm.assert_categorical_equal(result, expected)
+    result = Categorical([1, 2, 2 + 2j])
+    expected = Categorical([1.0 + 0.0j, 2.0 + 0.0j, 2.0 + 2.0j])
+    tm.assert_categorical_equal(result, expected)
+
+
 def test_multi_column_dtype_assignment():
     # GH #27583
     df = pd.DataFrame({"a": [0.0], "b": 0.0})