4 files changed, 35 insertions, 1 deletions
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 82c985fae2..aa7e206bb2 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Fix bug where `ActiveSupport::Timezone.all` would fail when tzinfo data for
+    any timezone defined in `ActiveSupport::MAPPING` is missing.
+
+    *Dominik Sander*
+
 *   Fix bug where `ActiveSupport::Cache` will massively inflate the storage
     size when compression is enabled (which is true by default). This patch
     does not attempt to repair existing data: please manually flush the cache
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index 9dfaddb825..5f709c5fd9 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -279,7 +279,8 @@ module ActiveSupport
 
         def zones_map
           @zones_map ||= MAPPING.each_with_object({}) do |(name, _), zones|
-            zones[name] = self[name]
+            timezone = self[name]
+            zones[name] = timezone if timezone
           end
         end
     end
diff --git a/activesupport/test/time_zone_test.rb b/activesupport/test/time_zone_test.rb
index 63ca22efb5..120afa61f2 100644
--- a/activesupport/test/time_zone_test.rb
+++ b/activesupport/test/time_zone_test.rb
@@ -725,6 +725,21 @@ class TimeZoneTest < ActiveSupport::TestCase
     assert_not_includes all_zones, galapagos
   end
 
+  def test_all_not_raises_exception_with_mizzing_tzinfo_data
+    mappings = {
+      "Puerto Rico" => "America/Unknown",
+      "Pittsburgh"  => "America/New_York"
+    }
+
+    with_tz_mappings(mappings) do
+      assert_nil ActiveSupport::TimeZone["Puerto Rico"]
+      assert_nil ActiveSupport::TimeZone[-9]
+      assert_nothing_raised do
+        ActiveSupport::TimeZone.all
+      end
+    end
+  end
+
   def test_index
     assert_nil ActiveSupport::TimeZone["bogus"]
     assert_instance_of ActiveSupport::TimeZone, ActiveSupport::TimeZone["Central Time (US & Canada)"]
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