Make ActiveSupport::TimeZone.all independent of previous lookups (#31176)

3 files changed, 23 insertions, 3 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 88bbafc3a8..3257c63fd2 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Make `ActiveSupport::TimeZone.all` return only time zones that are in
+    `ActiveSupport::TimeZone::MAPPING`.
+
+    Fixes #7245.
+
+    *Chris LaRose*
+
 *   MemCacheStore: Support expiring counters.
 
     Pass `expires_in: [seconds]` to `#increment` and `#decrement` options
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index b294d99fe0..07e37f5dd2 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -256,6 +256,13 @@ module ActiveSupport
         @country_zones[code] ||= load_country_zones(code)
       end
 
+      def clear() #:nodoc:
+        @lazy_zones_map = Concurrent::Map.new
+        @country_zones  = Concurrent::Map.new
+        @zones = nil
+        @zones_map = nil
+      end
+
       private
         def load_country_zones(code)
           country = TZInfo::Country.get(code)
@@ -269,9 +276,8 @@ module ActiveSupport
         end
 
         def zones_map
-          @zones_map ||= begin
-            MAPPING.each_key { |place| self[place] } # load all the zones
-            @lazy_zones_map
+          @zones_map ||= MAPPING.each_with_object({}) do |(name, _), zones|
+            zones[name] = self[name]
           end
         end
     end
diff --git a/activesupport/test/time_zone_test.rb b/activesupport/test/time_zone_test.rb
index 862e872494..405c8f315b 100644
--- a/activesupport/test/time_zone_test.rb
+++ b/activesupport/test/time_zone_test.rb
@@ -718,6 +718,13 @@ class TimeZoneTest < ActiveSupport::TestCase
     end
   end
 
+  def test_all_uninfluenced_by_time_zone_lookups_delegated_to_tzinfo
+    ActiveSupport::TimeZone.clear
+    galapagos = ActiveSupport::TimeZone["Pacific/Galapagos"]
+    all_zones = ActiveSupport::TimeZone.all
+    assert_not_includes all_zones, galapagos
+  end
+
   def test_index
     assert_nil ActiveSupport::TimeZone["bogus"]
     assert_instance_of ActiveSupport::TimeZone, ActiveSupport::TimeZone["Central Time (US & Canada)"]