TDD Bus implementation with Keith

bus.rb

class Bus

  def initialize
    @parked = true
    @number_of_children_in_bus = 0
  end

  def drive!
    @driving = true
    @parked = false
  end

  def driving?
    @driving == true
  end

  def park!
    @driving = false
    @parked = true
  end

  def parked?
    @parked == true
  end

  def run_over_children(number_of_children)
    if driving?
      "I hit #{number_of_children} children."
    else
      false
    end
  end

  def children
    @number_of_children_in_bus
  end

  def pick_up_children(number_of_children)
    if parked?
      @number_of_children_in_bus = @number_of_children_in_bus + number_of_children
    else
      false
    end
  end

  def drop_off_children(number_of_children)
    @number_of_children_in_bus = @number_of_children_in_bus - number_of_children
  end

end

bus_spec.rb

require 'rspec'
require './bus'
# rspec -fd -c bus_spec.rb


describe Bus do

  let(:bus) { Bus.new }

  it 'should start off parked' do
    bus.parked?.should be_true
  end

  it 'should not start off driving' do
    bus.driving?.should be_false
  end

  it 'should drive' do
    bus.drive!
    bus.driving?.should be_true
  end

  it 'should not be parked and driving at the same time' do
    bus.parked?.should be_true
    bus.drive!
    bus.driving?.should be_true
    bus.parked?.should be_false
  end

  it 'should be able to park' do
    bus.drive!
    bus.driving?.should be_true
    bus.park!
    bus.parked?.should be_true
    bus.driving?.should be_false
  end

  it 'should be able to run over x children' do
    bus.drive!
    bus.run_over_children(3).should == 'I hit 3 children.'
    bus.run_over_children(5).should == 'I hit 5 children.'
  end

  it 'must be driving in order to run over children' do
    bus.park!
    bus.run_over_children(3).should be_false
  end

  it 'should be able to pick up children and drop them off' do
    bus.children.should == 0

    bus.pick_up_children(3)
    bus.children.should == 3

    bus.pick_up_children(2)
    bus.children.should == 5

    bus.drop_off_children(4)
    bus.children.should == 1

    bus.drop_off_children(1)
    bus.children.should == 0
  end

  it 'must be parked in order to pick up children' do
    bus.drive!
    bus.children.should == 0
    bus.pick_up_children(2)
    bus.children.should == 0
  end

end

Gemfile

gem 'rspec'
gem 'debugger'