Add tests for time zone parsing, for "HH", "HH:MM" and "HH:MM:SS" forms.

Currently the second fails for negative offsets due to bugs in the 
parser, and the third fails because it doesn't even try to parse second 
offset values (as Python doesn't either).

tests/test_dates.py

@@ -3,6 +3,7 @@
 import unittest
 
 import psycopg2
+from psycopg2.tz import FixedOffsetTimezone
 import tests
 
 
@@ -103,6 +104,44 @@ def test_parse_datetime_microseconds(self):
         self.assertEqual(value.second, 29)
         self.assertEqual(value.microsecond, 123456)
 
+    def check_timezone(self, curs, str_offset, offset):
+        from datetime import datetime, timedelta
+        base = datetime(2007, 1, 1, 13, 30, 29)
+        base_str = '2007-01-01 13:30:29'
+
+        value = self.DATETIME(base_str + str_offset, curs)
+
+        # tzinfo instance is correct.
+        self.assertTrue(isinstance(value.tzinfo, FixedOffsetTimezone),
+                        "value's timezone is not a FixedOffsetTimezone")
+        self.assertEqual(value.tzinfo._offset, timedelta(seconds=offset))
+
+        # Datetime is correct.
+        self.assertEqual(value.replace(tzinfo=None), base)
+
+        # Offset from UTC is correct.
+        UTC = FixedOffsetTimezone(0, "UTC")
+        value_utc = value.astimezone(UTC).replace(tzinfo=None)
+        self.assertEqual(base - value_utc, timedelta(seconds=offset))
+
+    def test_parse_datetime_timezone_hours(self):
+        conn = psycopg2.connect(tests.dsn)
+        curs = conn.cursor()
+        self.check_timezone(curs, "+01", 3600)
+        self.check_timezone(curs, "-01", -3600)
+
+    def test_parse_datetime_timezone_hours_minutes(self):
+        conn = psycopg2.connect(tests.dsn)
+        curs = conn.cursor()
+        self.check_timezone(curs, "+01:15", 4500)
+        self.check_timezone(curs, "-01:15", -4500)
+
+    def test_parse_datetime_timezone_hours_minutes_seconds(self):
+        conn = psycopg2.connect(tests.dsn)
+        curs = conn.cursor()
+        self.check_timezone(curs, "+01:15:42", 4542)
+        self.check_timezone(curs, "-01:15:42", -4542)
+
     def test_parse_interval(self):
         value = self.INTERVAL('42 days 12:34:56.123456', None)
         self.assertNotEqual(value, None)