Lessons from the prime factorization dojo

prime_factor_decomposer.rb

module PrimeFactorDecomposer 
  def decompose(number)
    if number < 4
      number
    else
      [2,2]
    end
  end
end

prime_factor_decomposer_spec.rb

describe PrimeFactorDecomposer do
    include PrimeFactorDecomposer

     it "returns no prime factors for 1" do
    decompose(1).should be_empty
  end

  it "decomposes 2 into 2" do
    decompose(2).should be == [2]
  end

  it "decomposes 3 into 3" do
    decompose(3).should be == [3]
  end

  it "decomposes 4 into 2,2" do
    decompose(4).should be == [2,2]
  end
end