Fix exception in AS::Timezone.all when any tzinfo data is missing

Before this change missing timezone data for any of the time zones
defined in `ActiveSupport::Timezone::MAPPING` caused a `comparison of
NilClass with ActiveSupport::TimeZone failed` exception.

Attempting to get a timezone by passing a number/duration to `[]` or
calling `all` directly will try to sort sort the values of `zones_map`.
Those values are initialized by the return value of `create(zonename)`
which returns `nil` if `TZInfo` is unable to find the timezone
information.

In our case the exception was triggered by an outdated tzdata package
which did not include information for the "recently" added time zones.

Before 078421bacba178eac6a8e607b16f3f4511c5d72f `zones_map` only
returned the information that have been loaded into `@lazy_zone_map`
which ignored time zones for which the data could not be loaded, this
change restores the previous behaviour.

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