1 files changed, 13 insertions, 0 deletions
diff --git a/activesupport/test/time_zone_test_helpers.rb b/activesupport/test/time_zone_test_helpers.rb
index 051703a781..85ed727c9b 100644
--- a/activesupport/test/time_zone_test_helpers.rb
+++ b/activesupport/test/time_zone_test_helpers.rb
@@ -23,4 +23,17 @@ module TimeZoneTestHelpers
   ensure
     ActiveSupport.to_time_preserves_timezone = old_preserve_tz
   end
+
+  def with_tz_mappings(mappings)
+    old_mappings = ActiveSupport::TimeZone::MAPPING.dup
+    ActiveSupport::TimeZone.clear
+    ActiveSupport::TimeZone::MAPPING.clear
+    ActiveSupport::TimeZone::MAPPING.merge!(mappings)
+
+    yield
+  ensure
+    ActiveSupport::TimeZone.clear
+    ActiveSupport::TimeZone::MAPPING.clear
+    ActiveSupport::TimeZone::MAPPING.merge!(old_mappings)
+  end
 end