Merge pull request rails#53503 from Shopify/gm/add-max_value-to-big-integer

Add back max_value to `ActiveModel::BigInteger`

Author: gmcgibbon

activemodel/lib/active_model/type/big_integer.rb

@@ -47,6 +47,11 @@ def serialize_cast_value(value) # :nodoc:
       def serializable?(value, &_)
         true
       end
+
+      private
+        def max_value
+          ::Float::INFINITY
+        end
     end
   end
 end

activemodel/test/cases/type/big_integer_test.rb

@@ -5,6 +5,16 @@
 module ActiveModel
   module Type
     class BigIntegerTest < ActiveModel::TestCase
+      class CustomNumber
+        attr_reader :num
+
+        def initialize(num)
+          @num = num
+        end
+
+        alias_method :to_i, :num
+      end
+
       def test_type_cast_big_integer
         type = Type::BigInteger.new
         assert_equal 1, type.cast(1)
@@ -21,6 +31,13 @@ def test_large_values
         assert_equal 9999999999999999999999999999999, type.serialize(9999999999999999999999999999999)
       end
 
+      def test_integer_like_classes_that_are_greater_than_4_bytes_still_serialize
+        type = Type::BigInteger.new
+        large_number = 9999999999999999999999999999999
+
+        assert_equal large_number, type.serialize(CustomNumber.new(large_number))
+      end
+
       test "serialize_cast_value is equivalent to serialize after cast" do
         type = Type::BigInteger.new
         value = type.cast(9999999999999999999999999999999)