1 files changed, 7 insertions, 4 deletions

diff --git a/src/mailman/utilities/datetime.py b/src/mailman/utilities/datetime.py
index 7e727346d..1ee727da4 100644
--- a/src/mailman/utilities/datetime.py
+++ b/src/mailman/utilities/datetime.py
@@ -36,25 +36,27 @@ __all__ = [
 
 import datetime
 
+from mailman.testing import layers
+
 
 
 class DateFactory:
     """A factory for today() and now() that works with testing."""
 
-    # Set to True to produce predictable dates and times.
-    testing_mode = False
     # The predictable time.
     predictable_now = None
     predictable_today = None
 
     def now(self, tz=None):
+        # We can't automatically fast-forward because some tests require us to
+        # stay on the same day for a while, e.g. autorespond.txt.
         return (self.predictable_now
-                if self.testing_mode
+                if layers.is_testing()
                 else datetime.datetime.now(tz))
 
     def today(self):
         return (self.predictable_today
-                if self.testing_mode
+                if layers.is_testing()
                 else datetime.date.today())
 
     @classmethod
@@ -72,3 +74,4 @@ factory = DateFactory()
 factory.reset()
 today = factory.today
 now = factory.now
+layers.MockAndMonkeyLayer.register_reset(factory.reset)