Remove pytz as a dependency.

ChangeLog.rst

@@ -6,7 +6,8 @@ ChangeLog
 master
 ------
 
-No changes yet
+*New:*
+    - Remove pytz as a dependency.
 
 1.5.0 (15/01/2021)
 ------------------

requirements.txt

@@ -1,2 +1 @@
 Django>=1.11
-pytz>=2015.7

src/dirtyfields/compare.py

@@ -1,8 +1,7 @@
-import datetime
-import pytz
 import warnings
+from datetime import datetime, timezone
 
-from django.utils import timezone
+from django.utils import timezone as django_timezone
 
 
 def compare_states(new_state, original_state, compare_function, normalise_function):
@@ -33,13 +32,13 @@ def raw_compare(new_value, old_value):
     return new_value == old_value
 
 
-def timezone_support_compare(new_value, old_value, timezone_to_set=pytz.UTC):
+def timezone_support_compare(new_value, old_value, timezone_to_set=timezone.utc):
 
-    if not (isinstance(new_value, datetime.datetime) and isinstance(old_value, datetime.datetime)):
+    if not (isinstance(new_value, datetime) and isinstance(old_value, datetime)):
         return raw_compare(new_value, old_value)
 
-    db_value_is_aware = timezone.is_aware(old_value)
-    in_memory_value_is_aware = timezone.is_aware(new_value)
+    db_value_is_aware = django_timezone.is_aware(old_value)
+    in_memory_value_is_aware = django_timezone.is_aware(new_value)
 
     if db_value_is_aware == in_memory_value_is_aware:
         return raw_compare(new_value, old_value)
@@ -49,14 +48,14 @@ def timezone_support_compare(new_value, old_value, timezone_to_set=pytz.UTC):
         warnings.warn(u"DateTimeField received a naive datetime (%s)"
                       u" while time zone support is active." % new_value,
                       RuntimeWarning)
-        new_value = timezone.make_aware(new_value, timezone_to_set).astimezone(pytz.utc)
+        new_value = django_timezone.make_aware(new_value, timezone_to_set).astimezone(timezone.utc)
     else:
         # The db is not timezone aware, but the value we are passing for comparison is aware.
         warnings.warn(u"Time zone support is not active (settings.USE_TZ=False), "
                       u"and you pass a time zone aware value (%s)"
                       u" Converting database value before comparison." % new_value,
                       RuntimeWarning)
-        old_value = timezone.make_aware(old_value, pytz.utc).astimezone(timezone_to_set)
+        old_value = django_timezone.make_aware(old_value, timezone.utc).astimezone(timezone_to_set)
 
     return raw_compare(new_value, old_value)
 

tests-requirements.txt

@@ -1,5 +1,4 @@
 pytest==6.2.2
-pytz
 # Because we test a wide range of Django versions, leave versions of these unspecified.
 pytest-django
 jsonfield

tests/models.py

@@ -1,6 +1,6 @@
 from django.db import models
 from django.db.models.signals import pre_save
-from django.utils import timezone
+from django.utils import timezone as django_timezone
 from jsonfield import JSONField as JSONFieldThirdParty
 
 from dirtyfields import DirtyFieldsMixin
@@ -61,12 +61,15 @@ class ExpressionModelTest(DirtyFieldsMixin, models.Model):
 
 class DatetimeModelTest(DirtyFieldsMixin, models.Model):
     compare_function = (timezone_support_compare, {})
-    datetime_field = models.DateTimeField(default=timezone.now)
+    datetime_field = models.DateTimeField(default=django_timezone.now)
 
 
 class CurrentDatetimeModelTest(DirtyFieldsMixin, models.Model):
-    compare_function = (timezone_support_compare, {'timezone_to_set': timezone.get_current_timezone()})
-    datetime_field = models.DateTimeField(default=timezone.now)
+    compare_function = (
+        timezone_support_compare,
+        {'timezone_to_set': django_timezone.get_current_timezone()},
+    )
+    datetime_field = models.DateTimeField(default=django_timezone.now)
 
 
 class Many2ManyModelTest(DirtyFieldsMixin, models.Model):

tests/test_timezone_aware_fields.py

@@ -1,17 +1,16 @@
-import pytest
-import pytz
-from datetime import datetime
+from datetime import datetime, timedelta, timezone
 
-from django.utils import timezone
+import pytest
 from django.test.utils import override_settings
+from django.utils import timezone as django_timezone
 
 from .models import DatetimeModelTest, CurrentDatetimeModelTest
 
 
-@override_settings(USE_TZ=True, TIME_ZONE='America/Chicago')
+@override_settings(USE_TZ=True)
 @pytest.mark.django_db
 def test_datetime_fields_when_aware_db_and_naive_current_value():
-    tm = DatetimeModelTest.objects.create(datetime_field=datetime(2000, 1, 1, tzinfo=pytz.utc))
+    tm = DatetimeModelTest.objects.create(datetime_field=datetime(2000, 1, 1, tzinfo=timezone.utc))
 
     # Adding a naive datetime
     tm.datetime_field = datetime(2016, 1, 1)
@@ -23,7 +22,7 @@ def test_datetime_fields_when_aware_db_and_naive_current_value():
             r"while time zone support is active\."
         ),
     ):
-        assert tm.get_dirty_fields() == {'datetime_field': datetime(2000, 1, 1, tzinfo=pytz.utc)}
+        assert tm.get_dirty_fields() == {'datetime_field': datetime(2000, 1, 1, tzinfo=timezone.utc)}
 
 
 @override_settings(USE_TZ=False)
@@ -32,7 +31,7 @@ def test_datetime_fields_when_naive_db_and_aware_current_value():
     tm = DatetimeModelTest.objects.create(datetime_field=datetime(2000, 1, 1))
 
     # Adding an aware datetime
-    tm.datetime_field = datetime(2016, 1, 1, tzinfo=pytz.utc)
+    tm.datetime_field = datetime(2016, 1, 1, tzinfo=timezone.utc)
 
     with pytest.warns(
         RuntimeWarning,
@@ -46,12 +45,13 @@ def test_datetime_fields_when_naive_db_and_aware_current_value():
         assert tm.get_dirty_fields() == {'datetime_field': datetime(2000, 1, 1)}
 
 
+@override_settings(USE_TZ=True)
 @pytest.mark.django_db
 def test_datetime_fields_when_aware_db_and_aware_current_value():
-    aware_dt = timezone.now()
+    aware_dt = django_timezone.now()
     tm = DatetimeModelTest.objects.create(datetime_field=aware_dt)
 
-    tm.datetime_field = timezone.now()
+    tm.datetime_field = django_timezone.now()
 
     assert tm.get_dirty_fields() == {'datetime_field': aware_dt}
 
@@ -69,7 +69,7 @@ def test_datetime_fields_when_naive_db_and_naive_current_value():
 @override_settings(USE_TZ=True, TIME_ZONE='America/Chicago')
 @pytest.mark.django_db
 def test_datetime_fields_with_current_timezone_conversion():
-    tm = CurrentDatetimeModelTest.objects.create(datetime_field=datetime(2000, 1, 1, 12, 0, 0, tzinfo=pytz.utc))
+    tm = CurrentDatetimeModelTest.objects.create(datetime_field=datetime(2000, 1, 1, 12, 0, 0, tzinfo=timezone.utc))
 
     # Adding a naive datetime, that will be converted to local timezone.
     tm.datetime_field = datetime(2000, 1, 1, 6, 0, 0)
@@ -91,9 +91,9 @@ def test_datetime_fields_with_current_timezone_conversion():
 def test_datetime_fields_with_current_timezone_conversion_without_timezone_support():
     tm = CurrentDatetimeModelTest.objects.create(datetime_field=datetime(2000, 1, 1, 12, 0, 0))
 
-    # Adding an aware datetime
-    chicago_timezone = pytz.timezone('America/Chicago')
-    tm.datetime_field = chicago_timezone.localize(datetime(2000, 1, 1, 6, 0, 0), is_dst=None)
+    # Adding an aware datetime, Chicago is UTC-6h
+    chicago_timezone = timezone(timedelta(hours=-6))
+    tm.datetime_field = datetime(2000, 1, 1, 6, 0, 0, tzinfo=chicago_timezone)
 
     # If the database is naive, then we consider that it is defined as in UTC.
     with pytest.warns(