require_relative '../../spec_helper' require 'prime' describe "Prime#prime?" do it "returns a true value for prime numbers" do Prime.prime?(2).should be_true Prime.prime?(3).should be_true Prime.prime?(2**31-1).should be_true # 8th Mersenne prime (M8) end it "returns a false value for composite numbers" do Prime.prime?(4).should be_false Prime.prime?(15).should be_false Prime.prime?(2**32-1).should be_false Prime.prime?( (2**17-1)*(2**19-1) ).should be_false # M6*M7 end end