fix utc comprehension

Author: Jonathan Eliashiv

pandas/_libs/src/ujson/python/date_conversions.c

@@ -96,6 +96,9 @@ char *PyDateTimeToIso(PyObject *obj, NPY_DATETIMEUNIT base,
 
         if ((tzinfo != NULL) && (tzinfo != Py_None)){
             tzoffset = get_tzoffset_from_pytzinfo(tzinfo, &dts);
+            if (tzoffset == 0){
+                tzoffset = -1;
+            }
         }
     }
 

pandas/tests/io/json/test_pandas.py

@@ -1185,8 +1185,6 @@ def test_sparse(self):
         "ts",
         [
             Timestamp("2013-01-10 05:00:00Z"),
-            Timestamp("2013-01-10 00:00:00", tz="US/Eastern"),
-            Timestamp("2013-01-10 00:00:00-0500"),
         ],
     )
     def test_tz_is_utc(self, ts):
@@ -1198,12 +1196,26 @@ def test_tz_is_utc(self, ts):
         dt = ts.to_pydatetime()
         assert dumps(dt, iso_dates=True) == exp
 
+    @pytest.mark.parametrize(
+        "ts",
+        [
+            Timestamp("2013-01-10 00:00:00", tz="US/Eastern"),
+            Timestamp("2013-01-10 00:00:00-0500"),
+        ],
+    )
+    def test_tz_is_localized(self, ts):
+        from pandas.io.json import dumps
+
+        exp = '"2013-01-10T00:00:00.000-05:00"'
+
+        assert dumps(ts, iso_dates=True) == exp
+        dt = ts.to_pydatetime()
+        assert dumps(dt, iso_dates=True) == exp
+    
     @pytest.mark.parametrize(
         "tz_range",
         [
-            pd.date_range("2013-01-01 05:00:00Z", periods=2),
-            pd.date_range("2013-01-01 00:00:00", periods=2, tz="US/Eastern"),
-            pd.date_range("2013-01-01 00:00:00-0500", periods=2),
+            pd.date_range("2013-01-01 05:00:00Z", periods=2)
         ],
     )
     def test_tz_range_is_utc(self, tz_range):
@@ -1222,6 +1234,30 @@ def test_tz_range_is_utc(self, tz_range):
         df = DataFrame({"DT": dti})
         result = dumps(df, iso_dates=True)
         assert result == dfexp
+    
+    @pytest.mark.parametrize(
+        "tz_range",
+        [
+            pd.date_range("2013-01-01 00:00:00", periods=2, tz='US/Eastern'),
+            pd.date_range("2013-01-01 00:00:00-0500", periods=2)
+        ],
+    )
+    def test_tz_range_is_local(self, tz_range):
+        from pandas.io.json import dumps
+
+        exp = '["2013-01-01T05:00:00.000Z","2013-01-02T05:00:00.000Z"]'
+        dfexp = (
+            '{"DT":{'
+            '"0":"2013-01-01T00:00:00.000-05:00",'
+            '"1":"2013-01-02T00:00:00.000-05:00"}}'
+        )
+
+        assert dumps(tz_range, iso_dates=True) == exp
+        dti = DatetimeIndex(tz_range)
+        assert dumps(dti, iso_dates=True) == exp
+        df = DataFrame({"DT": dti})
+        result = dumps(df, iso_dates=True)
+        assert result == dfexp
 
     def test_read_inline_jsonl(self):
         # GH9180

pandas/tests/io/json/test_ujson.py

@@ -391,7 +391,8 @@ def test_encode_time_conversion_basic(self, test):
 
     def test_encode_time_conversion_pytz(self):
         # see gh-11473: to_json segfaults with timezone-aware datetimes
-        test = datetime.datetime(2021, 5, 25, 10, 12, 15, 343243, pytz.timezone('US/Eastern'))
+        test = datetime.datetime(2021, 5, 25, 10, 12, 15, 343243, \
+                                 pytz.timezone('US/Eastern'))
         output = ujson.encode(test, iso_dates=True, date_unit='us')
         expected = f'"{test.isoformat()}"'
         assert expected == output