stack level too deep

[m5rk]

This rather benign appearing spec:

        it 'loses its mind' do
          expect({
            m: [
              {
                s: {
                  a: :i,
                  b: "",
                  c: :r
                }
              }
            ],
            s: {
              a: :o,
              b: nil,
              c: :r
            }
          }).to match_json_expression({
            m: [
              {
                s: {
                  a: :i,
                  b: "",
                  c: :r
                }
              }
            ],
            s: {
              a: :o,
              b: nil,
              c: :r
            }
          })
        end

blows up:

  Failure/Error: expect({
  SystemStackError:
    stack level too deep

[m5rk]

Note, calling .to_json fixes this, but I still think you may want to address this issue (by coercing the input to json or blowing up if it's not):

expect(foo.to_json).to match_json_expression(json)