Optimized make_aware/naive by removing redundant checks. Refs #22625.

Also added tests with pytz and removed misplaced tests.

1 files changed, 12 insertions, 8 deletions

diff --git a/django/utils/timezone.py b/django/utils/timezone.py
index 8138767fb2..0c44d4fd4d 100644
--- a/django/utils/timezone.py
+++ b/django/utils/timezone.py
@@ -306,9 +306,11 @@ def localtime(value, timezone=None):
     """
     if timezone is None:
         timezone = get_current_timezone()
+    # If `value` is naive, astimezone() will raise a ValueError,
+    # so we don't need to perform a redundant check.
     value = value.astimezone(timezone)
     if hasattr(timezone, 'normalize'):
-        # available for pytz time zones
+        # This method is available for pytz time zones.
         value = timezone.normalize(value)
     return value
 
@@ -351,13 +353,15 @@ def make_aware(value, timezone):
     """
     Makes a naive datetime.datetime in a given time zone aware.
     """
-    if is_aware(value):
-        raise ValueError("make_aware expects a naive value, got %s" % value)
     if hasattr(timezone, 'localize'):
-        # available for pytz time zones
+        # This method is available for pytz time zones.
         return timezone.localize(value, is_dst=None)
     else:
-        # may be wrong around DST changes
+        # Check that we won't overwrite the timezone of an aware datetime.
+        if is_aware(value):
+            raise ValueError(
+                    "make_aware expects a naive datetime, got %s" % value)
+        # This may be wrong around DST changes!
         return value.replace(tzinfo=timezone)
 
 
@@ -365,10 +369,10 @@ def make_naive(value, timezone):
     """
     Makes an aware datetime.datetime naive in a given time zone.
     """
-    if is_naive(value):
-        raise ValueError("make_naive expects an aware value, got %s" % value)
+    # If `value` is naive, astimezone() will raise a ValueError,
+    # so we don't need to perform a redundant check.
     value = value.astimezone(timezone)
     if hasattr(timezone, 'normalize'):
-        # available for pytz time zones
+        # This method is available for pytz time zones.
         value = timezone.normalize(value)
     return value.replace(tzinfo=None)