calculator_spec.rb

# another way of doing require_relative
require "#{File.dirname(__FILE__)}/calculator"
require_relative '../../spec_helper'

describe Calculator do

  before do
    @calculator = Calculator.new
  end

  describe "#sum" do
    it "computes the sum of an empty array" do
      @calculator.sum([]).should == 0
    end

    it "computes the sum of an array of one number" do
      @calculator.sum([7]).should == 7
    end

    it "computes the sum of an array of two numbers" do
      @calculator.sum([7,11]).should == 18
    end

    it "computes the sum of an array of many numbers" do
      @calculator.sum([1,3,5,7,9]).should == 25
    end
  end

  # Once the above tests pass,
  # write tests and code for the following:
  describe "#multiply" do
  	it "multiplies two numbers" do
		@calculator.multiply(2,2).should eq 4
	end

  	it "multiplies an array of numbers" do
		@calculator.multiply([2,2]).should eq 4
  	end
  end

  it "raises one number to the power of another number" do
  	p = 1
	32.times{ p *= 2 }
	@calculator.pow(2,32).should eq p
  end

  # http://en.wikipedia.org/wiki/Factorial
  describe "#factorial" do
    it "computes the factorial of 0" do
    	@calculator.fac(0).should eq 1
    end
    it "computes the factorial of 1" do
    	@calculator.fac(1).should eq 1
    end

    it "computes the factorial of 2" do
    	@calculator.fac(2).should eq 2
    end

    it "computes the factorial of 5" do
    	@calculator.fac(5).should eq 120
    end

    it "computes the factorial of 10" do
    	@calculator.fac(10).should eq 3628800
    end

  end

end