Update test case for TZ aware attributes

The test added in 42418cfc94d1356d35d28d786f63e7fab9406ad6 wasn't
actually testing anything, since the bug was with TZ aware attributes
only.

activerecord/test/cases/adapters/postgresql/infinity_test.rb

@@ -1,6 +1,8 @@
 require "cases/helper"
 
 class PostgresqlInfinityTest < ActiveRecord::TestCase
+  include InTimeZone
+
   class PostgresqlInfinity < ActiveRecord::Base
   end
 
@@ -42,9 +44,17 @@ class PostgresqlInfinity < ActiveRecord::Base
     assert_equal Float::INFINITY, record.datetime
   end
 
-  test "assigning 'infinity' on a datetime column" do
-    record = PostgresqlInfinity.create!(datetime: "infinity")
-    assert_equal Float::INFINITY, record.datetime
-    assert_equal record.datetime, record.reload.datetime
+  test "assigning 'infinity' on a datetime column with TZ aware attributes" do
+    begin
+      in_time_zone "Pacific Time (US & Canada)" do
+        record = PostgresqlInfinity.create!(datetime: "infinity")
+        assert_equal Float::INFINITY, record.datetime
+        assert_equal record.datetime, record.reload.datetime
+      end
+    ensure
+      # setting time_zone_aware_attributes causes the types to change.
+      # There is no way to do this automatically since it can be set on a superclass
+      PostgresqlInfinity.reset_column_information
+    end
   end
 end