Fixes setters and modifiers (start_of/end_of) to properly apply transitions.

Fixes #36

Author: sdispater

pendulum/pendulum.py

@@ -480,25 +480,30 @@ def copy(self):
     ### Getters/Setters
 
     def year_(self, year):
-        return self.instance(self._datetime.replace(year=year))
+        return self._setter(year=year)
 
     def month_(self, month):
-        return self.instance(self._datetime.replace(month=month))
+        return self._setter(month=month)
 
     def day_(self, day):
-        return self.instance(self._datetime.replace(day=day))
+        return self._setter(day=day)
 
     def hour_(self, hour):
-        return self.instance(self._datetime.replace(hour=hour))
+        return self._setter(hour=hour)
 
     def minute_(self, minute):
-        return self.instance(self._datetime.replace(minute=minute))
+        return self._setter(minute=minute)
 
     def second_(self, second):
-        return self.instance(self._datetime.replace(second=second))
+        return self._setter(second=second)
 
     def microsecond_(self, microsecond):
-        return self.instance(self._datetime.replace(microsecond=microsecond))
+        return self._setter(microsecond=microsecond)
+
+    def _setter(self, **kwargs):
+        kwargs['tzinfo'] = None
+
+        return self.instance(self._datetime.replace(**kwargs), self._tz)
 
     def timezone_(self, tz):
         tz = self._safe_create_datetime_zone(tz)
@@ -651,10 +656,11 @@ def with_date(self, year, month, day):
         :rtype: Pendulum
         """
         dt = self._datetime.replace(
-            year=int(year), month=int(month), day=int(day)
+            year=int(year), month=int(month), day=int(day),
+            tzinfo=None
         )
 
-        return self.instance(dt)
+        return self.instance(dt, self._tz)
 
     def with_time(self, hour, minute, second, microsecond=0):
         """
@@ -676,10 +682,11 @@ def with_time(self, hour, minute, second, microsecond=0):
         """
         dt = self._datetime.replace(
             hour=int(hour), minute=int(minute), second=int(second),
-            microsecond=microsecond
+            microsecond=microsecond,
+            tzinfo=None
         )
 
-        return self.instance(dt)
+        return self.instance(dt, self._tz)
 
     def with_date_time(self, year, month, day, hour, minute, second, microsecond=0):
         """
@@ -697,10 +704,11 @@ def with_date_time(self, year, month, day, hour, minute, second, microsecond=0):
         dt = self._datetime.replace(
             year=year, month=month, day=day,
             hour=int(hour), minute=int(minute), second=int(second),
-            microsecond=microsecond
+            microsecond=microsecond,
+            tzinfo=None
         )
 
-        return self.instance(dt)
+        return self.instance(dt, self._tz)
 
     def with_time_from_string(self, time):
         """

tests/pendulum_tests/test_fluent_setters.py

@@ -79,6 +79,19 @@ def test_fluid_with_date(self):
         self.assertEqual(7, d.month)
         self.assertEqual(2, d.day)
 
+    def test_fluid_with_date_with_transition(self):
+        d = Pendulum.create(2013, 3, 31, 0, 0, 0, 0, 'Europe/Paris')
+        new = d.with_date(2013, 4, 1)
+        self.assertIsInstanceOfPendulum(new)
+        self.assertEqual(2013, new.year)
+        self.assertEqual(4, new.month)
+        self.assertEqual(1, new.day)
+        self.assertEqual(7200, new.offset)
+        self.assertEqual(2013, d.year)
+        self.assertEqual(3, d.month)
+        self.assertEqual(31, d.day)
+        self.assertEqual(3600, d.offset)
+
     def test_fluid_set_time(self):
         d = Pendulum.create(2016, 7, 2, 0, 41, 20)
         new = d.with_time(5, 32, 49)
@@ -90,6 +103,14 @@ def test_fluid_set_time(self):
         self.assertEqual(41, d.minute)
         self.assertEqual(20, d.second)
 
+    def test_fluid_set_time_with_transition(self):
+        d = Pendulum.create(2013, 3, 31, 0, 0, 0, 0, 'Europe/Paris')
+        new = d.with_time(2, 30, 0)
+        self.assertIsInstanceOfPendulum(new)
+        self.assertEqual(3, new.hour)
+        self.assertEqual(30, new.minute)
+        self.assertEqual(0, new.second)
+
     def test_fluid_set_timestamp(self):
         d = Pendulum.create(2016, 7, 2, 0, 41, 20)
         new = d.timestamp_(0)

tests/pendulum_tests/test_start_end_of.py

@@ -191,3 +191,17 @@ def start_of_with_invalid_unit(self):
 
     def end_of_with_invalid_unit(self):
         self.assertRaises(ValueError, Pendulum.now().end_of('invalid'))
+
+    def test_start_of_with_transition(self):
+        d = Pendulum(2013, 10, 27, 23, 59, 59, tzinfo='Europe/Paris')
+        self.assertEqual(3600, d.offset)
+        self.assertEqual(7200, d.start_of('month').offset)
+        self.assertEqual(7200, d.start_of('day').offset)
+        self.assertEqual(3600, d.start_of('year').offset)
+
+    def test_end_of_with_transition(self):
+        d = Pendulum(2013, 3, 31, tzinfo='Europe/Paris')
+        self.assertEqual(3600, d.offset)
+        self.assertEqual(7200, d.end_of('month').offset)
+        self.assertEqual(7200, d.end_of('day').offset)
+        self.assertEqual(3600, d.end_of('year').offset)