Change the initialize method in your model to be:

def initialize(options={})
self.model = options[:model] || ‘Volvo’
self.year = options[:year] || 2007
self.color = options[:color] || ‘unknown’
end

Notice the addition of the curly braces after ‘options’. The initialize method had one argument declared and was giving you an error if you didn’t send an argument. Now, if no argument is sent, it will not give an error, but instead set options equal to an empty hash. In Ruby it is always true that the number of arguments sent to a method must match the number declared, unless you provide default values to fall back on.

On the bright side, now you see firsthand how testing can identify problems!

in your test_initialize, when you do default_car = Car.new and don’t pass it the hash, that doesn’t work for me.

I get an ArgumentException:

1) Error:
test_initialize(CarTest):
ArgumentError: wrong number of arguments (0 for 1)
car_test.rb:34:in `initialize’
car_test.rb:34:in `new’
car_test.rb:34:in `test_initialize’

I’m set up almost identically to your example:

class Car
attr_accessor :model, :year, :color

def initialize(options)
self.model = options[:model] || ‘Volvo’
self.year = (options[:year] || 2008).to_i
self.color = options[:color] || ‘unknown’
end
…
end

and CarTest:

def test_initialize
[34] default_car = Car.new
assert_equal(’volvo’, default_car.model)
assert_equal(2008, default_car.year)
assert_equal(’unknown’, default_car.color)
…
end

Line [34] is marked.

my ruby version: ruby 1.8.6 (2007-06-07 patchlevel 36) [i486-linux]

Everything else works as expected, as long as I’m passing in some hash. What is it that I’m not getting?