wagon_string.rb

class WagonString
  def initialize(string)
    # TODO: store the string as array of characters
  end

  def to_s
    # TODO: convert into a Ruby String
  end

  def reverse
    # TODO: return a new WagonString with reversed characters
  end

  def reverse!
    # TODO:
    # - reverse the characters in-place
    # - return itself without creating a new WagonString instance
  end
end


def assert(condition, message = "Panic")
  raise message unless condition
end

def test_internal_data
  hello = WagonString.new('hello')

  assert hello.instance_variables.size == 1, 'should contain one and only one ivar'
  ivar = hello.instance_variables.first
  assert hello.instance_variable_get(ivar).is_a?(Array), 'the ivar should be an array'
end

def test_to_s
  hello = WagonString.new('hello')

  assert hello.to_s == 'hello', "should convert into String 'hello'"
end

def test_reverse
  hello = WagonString.new('hello')

  assert hello.reverse.to_s == 'olleh', "should reverse into WagonString 'olleh'"
end

def test_reverse_return_wagon_string
  hello = WagonString.new('hello')

  assert hello.reverse.is_a?(WagonString), "should return a WagonString"
end

def test_reverse_do_not_modify_original
  hello = WagonString.new('hello')

  hello.reverse

  assert hello.to_s == 'hello', "should not change the original object"
end

def test_reverse_bang
  hello = WagonString.new('hello')

  assert hello.reverse!.to_s == 'olleh', "should reverse into WagonString 'olleh'"
end

def test_reverse_bang_return_wagon_string
  hello = WagonString.new('hello')

  assert hello.reverse!.is_a?(WagonString), "should return a WagonString"
end

def test_reverse_new_object
  hello = WagonString.new('hello')

  assert hello.object_id != hello.reverse.object_id, "should return a new object"
end

def test_reverse_bang_no_new_object
  hello = WagonString.new('hello')

  assert hello.object_id == hello.reverse!.object_id, "should return the same object"
end

test_internal_data
test_to_s
test_reverse
test_reverse_return_wagon_string
test_reverse_do_not_modify_original
test_reverse_bang
test_reverse_bang_return_wagon_string
test_reverse_new_object
test_reverse_bang_no_new_object

puts "yay it works"