Move the appropriate type tests to the Active Model suite

Any tests for a type which is not overridden by Active Record, and does
not test the specifics of the attributes API interacting in more complex
ways have no reason to be in the Active Record suite. Doing this
revealed that the implementation of the date and time types in AM was
actually completely broken, and incapable of returning any value other
than `nil`.

1 files changed, 8 insertions, 2 deletions

diff --git a/activemodel/lib/active_model/type/helpers/time_value.rb b/activemodel/lib/active_model/type/helpers/time_value.rb
index c55bb1e136..0a0e58654b 100644
--- a/activemodel/lib/active_model/type/helpers/time_value.rb
+++ b/activemodel/lib/active_model/type/helpers/time_value.rb
@@ -1,3 +1,5 @@
+require "active_support/core_ext/time/zones"
+
 module ActiveModel
   module Type
     module Helpers
@@ -21,11 +23,15 @@ module ActiveModel
         end
 
         def is_utc?
-          ::Time.zone_default =~ 'UTC'
+          ::Time.zone_default.nil? || ::Time.zone_default =~ 'UTC'
         end
 
         def default_timezone
-          ::Time.zone_default
+          if is_utc?
+            :utc
+          else
+            :local
+          end
         end
 
         def type_cast_for_schema(value)