Address whatsnew and test comments

Author: mroeschke

doc/source/whatsnew/v0.21.0.txt

@@ -231,7 +231,7 @@ Previously, :func:`to_datetime` did not localize datetime ``Series`` data when `
 
      pd.to_datetime(s, utc=True)
 
-Additionally, DataFrames with datetime columns returned by :func:`read_sql_table` and :func:`read_sql_query` with the `parse_dates` argument specified will also be localized to UTC only if the original SQL columns were timezone aware datetime columns.
+Additionally, DataFrames with datetime columns that were parsed by :func:`read_sql_table` and :func:`read_sql_query` will also be localized to UTC only if the original SQL columns were timezone aware datetime columns.
 
 .. _whatsnew_0210.api:
 

pandas/tests/indexes/datetimes/test_tools.py

@@ -265,10 +265,10 @@ def test_to_datetime_tz_pytz(self):
                               (list, DatetimeIndex, tm.assert_index_equal),
                               (np.array, DatetimeIndex, tm.assert_index_equal),
                               (Series, Series, tm.assert_series_equal)])
-    def test_to_datetime_utc_true_with_constructors(self,
-                                                    init_constructor,
-                                                    end_constructor,
-                                                    test_method):
+    def test_to_datetime_utc_true(self,
+                                  init_constructor,
+                                  end_constructor,
+                                  test_method):
         # See gh-11934 & gh-6415
         data = ['20100102 121314', '20100102 121315']
         expected_data = [pd.Timestamp('2010-01-02 12:13:14', tz='utc'),
@@ -292,9 +292,13 @@ def test_to_datetime_utc_true_with_series_single_value(self):
         expected = pd.Series([pd.Timestamp(ts, tz='utc')])
         tm.assert_series_equal(result, expected)
 
-    @pytest.mark.parametrize("dtype", [None, 'datetime64[ns]'])
-    def test_to_datetime_utc_true_with_naive_series(self, dtype):
-        test_dates = ['2013-01-01 00:00:00-01:00'] * 10
+    @pytest.mark.parametrize("data, dtype",
+                             [('2013-01-01 00:00:00-01:00', None), 
+                              ('2013-01-01 00:00:00-01:00','datetime64[ns]'),
+                              ('2013-01-01 01:00:00', None),
+                              ('2013-01-01 01:00:00', 'datetime64[ns]')])
+    def test_to_datetime_utc_true_with_naive_dtype_series(self, data, dtype):
+        test_dates = [data] * 10
         ser = pd.Series(test_dates, dtype=dtype)
         result = pd.to_datetime(ser, utc=True)
         expected_data = [pd.Timestamp('20130101 01:00:00', tz='utc')] * 10

pandas/tests/io/test_sql.py

@@ -1312,6 +1312,8 @@ def check(col):
         assert is_datetime64tz_dtype(col.dtype)
         assert str(col.dt.tz) == 'UTC'
         expected = sql.read_sql_table("types_test_data", self.conn)
+        col = expected.DateColWithTz
+        assert is_datetime64tz_dtype(col.dtype)
         # Removed ".astype('datetime64[ns, UTC]')"after GH 6415 was fixed
         tm.assert_series_equal(df.DateColWithTz, expected.DateColWithTz)