sequence_spec.rb

require 'rubygems'
require 'rspec'
require 'sequence'

describe Sequence do
  
  describe "validation" do
    
    it "should be able to sum its items" do
      sequence = Sequence.new(1, 2, 3, 4)
      sequence.sum.should == 10
    end
    
    it "is valid if the sum is 15" do
      sequence = Sequence.new(1, 1, 7, 6)
      sequence.should be_valid
      sequence = Sequence.new(1, 1, 7, 7)
      sequence.should_not be_valid
    end
    
    it "is invalid if there is no pair" do
      sequence = Sequence.new(8, 7)
      sequence.should_not have_digit_pair
      sequence.should_not be_valid
    end
    
    it "is invalid if there is a digit trio" do
      sequence = Sequence.new(1, 1, 1, 5, 7)
      sequence.should have_digit_trio
      sequence.should_not be_valid
    end
    
  end
  
  describe "sequencing" do
    
    it "should start with 1" do
      sequence = Sequence.new
      sequence.next.elements.should == [1]
    end
    
    it "a sequence with a low sum should spawn a new element" do
      sequence = Sequence.new(1)
      sequence.next.elements.should == [1, 1]
    end
    
    it "a sequence with a low sum should spawn a new element in numerical order" do
      sequence = Sequence.new(1, 1, 2)
      sequence.next.elements.should == [1, 1, 2, 2]
    end
    
    it "a sequence with a trio should increase its last element" do
      sequence = Sequence.new(1, 1, 1)
      sequence.next.elements.should == [1, 1, 2]
    end
    
    it "a sequence whose sum is too high should back up an element" do
      sequence = Sequence.new(1, 1, 2, 2, 3, 3, 4)
      sequence.next.elements.should == [1, 1, 2, 2, 3, 4]
    end
    
    it "a sequence should not let a digit get over 9" do
      sequence = Sequence.new(1, 9, 5)
      sequence.next.elements.should == [2]
    end
    
    it "the last sequence should end" do
      sequence = Sequence.new(9, 6)
      sequence.next.should be_nil
    end
    
  end
  
end