add missing assertion

Author: MarcoGorelli

pandas/tests/series/methods/test_update.py

@@ -67,6 +67,7 @@ def test_update_dtypes(self, other, dtype, expected, raises):
                 ser.update(other)
         else:
             ser.update(other)
+            tm.assert_series_equal(ser, expected)
 
     @pytest.mark.parametrize(
         "values, other, expected",