A spec level overview of rspec_mocks and rspec_spies syntax

gistfile1.rb

# When using the gems rspec_mocks and rspec_spies

class Widget
  def a_method
    'I am a method!'
  end
end

describe Widget do
  let(:item) {Widget.new}
  context 'arguments' do
    it 'works with returning multiple values based on passed in arguments' do
      item.stub(:a_method).with(2).and_return { 'two!'}
      item.stub(:a_method).with(3).and_return { 'three!'}
      item.a_method(3).should == 'three!'
      item.a_method(2).should == 'two!'
      expect {item.a_method(1)}.to raise_error
    end

    it 'works with returning multiple values for a method with multiple args' do
      item.stub(:a_method).with(anything, 'foo').and_return { 'three!'}
      item.stub(:a_method).with(anything, 'bar').and_return { 'two!'}
      item.a_method(1, 'foo').should == 'three!'
      item.a_method(1, 'bar').should == 'two!'
      expect {item.a_method(1, 'baz')}.to raise_error
    end

    it 'allows you to specify the number of arguments' do
      item.stub(:a_method).with(anything, anything).and_return { 'win!'}
      item.a_method(1,2).should == 'win!'
      expect {item.a_method(2)}.to raise_error
      expect {item.a_method(1,2,3)}.to raise_error
    end

    it 'blocks rock!' do
      item.stub(:a_method).with(anything, anything) do |arg1, arg2|
        "#{arg1} is a thing! so is #{arg2}."
      end
      item.a_method('Frog', 'dog').should == "Frog is a thing! so is dog."
    end
  end

  it 'allows you to stub methods that do not exist' do
    item.stub(:a_method_that_doesnt_exist)
    expect { item.a_method_that_doesnt_exist }.not_to raise_error
  end

  it 'stubbing class methods does not overwrite instance methods' do
    Widget.stub(:widge).and_return('widged')
    Widget.widge.should == 'widged'
    Widget.new.a_method.should == 'I am a method!'
  end

  describe 'spies' do
    it 'allows you to spy on things' do
      item.stub(:a_method).with(anything)
      item.a_method('foooo!')
      item.should have_received(:a_method).with('foooo!')
    end

    it 'allows you to spy and still call the original method' do
      item.stub(:a_method).and_call_original
      item.a_method.should == 'I am a method!'
      item.should have_received(:a_method)
    end
  end
end