Add test for #15966 (#18170)

Author: watercrossing

pandas/tests/frame/test_timeseries.py

@@ -677,3 +677,12 @@ def test_tz_convert_and_localize(self, fn):
         with assert_raises_regex(ValueError, 'not valid'):
             df = DataFrame(index=l0)
             df = getattr(df, fn)('US/Pacific', level=1)
+
+    @pytest.mark.parametrize('timestamps', [
+        [Timestamp('2012-01-01 13:00:00+00:00')] * 2,
+        [Timestamp('2012-01-01 13:00:00')] * 2])
+    def test_tz_aware_scalar_comparison(self, timestamps):
+        # Test for issue #15966
+        df = DataFrame({'test': timestamps})
+        expected = DataFrame({'test': [False, False]})
+        assert_frame_equal(df == -1, expected)