I like is_a? and instance_of? more than ===, it is implicit

very clever

  begin
    button = Integer(button)
    level = Integer(level)  
  rescue
    return 0
  end

using rescue to assure input is correct type

** Is it a correct or normal ruby way? **

Test.expect(solution((1..3).to_a, 1, 'a') == 2)
Test.expect(solution((1..3).to_a, -1, 'a') == 3, 'Using a negative index returned the wrong value.')
Test.expect(solution((1..3).to_a, -5, 'a') == 'a', 'Using a negative index returned the wrong value.')
Test.expect(solution((1..3).to_a, -3, 'a') == 1, 'Using a negative index returned the default value when it should have returned the first value within the array.')
Test.expect(solution((1..5).to_a, 10, 'a') == 'a', 'solution did not return default value when given an index that was out of range')
Test.expect(solution([nil, nil], 0, 'a') == nil, "solution([nil, nil], 0, 'a') should have returned nil but instead got #{solution([nil, nil], 0, 'a') || 'nil'}")