1) BSON::Int64#from_bson when the integer is within the MRI Fixnum range when using MRI deserializes to a Fixnum object
     Failure/Error: expect(described_class.from_bson(bson).class).to be(Fixnum)
       expected #<Class:1071232452> => Fixnum
            got #<Class:1071230868> => Bignum
       Compared using equal?, which compares object identity,
       but expected and actual are not the same object. Use
       `expect(actual).to eq(expected)` if you don't care about
       object identity in this example.
       Diff:
       @@ -1,2 +1,2 @@
       -Fixnum
       +Bignum
     # ./spec/bson/int64_spec.rb:83:in `block (5 levels) in <top (required)>'