test_fizz_buzz.rb

def test_fizzbuzz_de_1_a_20
    sequence = []
    1.upto(20) do |n|
        fizzbuzz = FizzBuzz.new(n)
	sequence.push(fizzbuzz.run)
    end
    assert_equal '1,2,fizz,4,buzz,fizz,7,8,fizz,buzz,11,fizz,13,14,fizzbuzz,16,17,fizz,19,buzz', sequence.join(",")
end

Last test that was lacking in the codingdojo we did last saturday. I don't like the idea of passing the number as an argument to the constructor. But the actual implementation is quite readable.