Consolidate testing of update_all type casting

We have several test cases on "tricky" types that are essentially
testing that `update_all` goes through the same type casting behavior as
a normal assignment + save. We recently had another case to add this
test for another type in https://github.com/rails/rails/pull/12742.

Rather than testing this separately for every type which is "tricky"
when round tripping, let's instead have a fairly exhaustive test that
ensures we're getting the correct values at every step for `update_all`.
Given the structure of the code now, we can be confident that if the
type is correct, and `update_all` is type casting correctly, we're going
to get the right behavior for all types.

1 files changed, 28 insertions, 0 deletions

diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index fb0b906c07..3280945d09 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -235,5 +235,33 @@ module ActiveRecord
       posts_with_special_comments_with_ratings = Post.group("posts.id").joins(:special_comments).merge(special_comments_with_ratings)
       assert_equal 3, authors(:david).posts.merge(posts_with_special_comments_with_ratings).count.length
     end
+
+    class EnsureRoundTripTypeCasting < ActiveRecord::Type::Value
+      def type
+        :string
+      end
+
+      def type_cast_from_database(value)
+        raise value unless value == "type cast for database"
+        "type cast from database"
+      end
+
+      def type_cast_for_database(value)
+        raise value unless value == "value from user"
+        "type cast for database"
+      end
+    end
+
+    class UpdateAllTestModel < ActiveRecord::Base
+      self.table_name = 'posts'
+
+      attribute :body, EnsureRoundTripTypeCasting.new
+    end
+
+    def test_update_all_goes_through_normal_type_casting
+      UpdateAllTestModel.update_all(body: "value from user", type: nil) # No STI
+
+      assert_equal "type cast from database", UpdateAllTestModel.first.body
+    end
   end
 end