gistfile1.txt

# Rspec Template
# --------------

# 1) Setup the subject.  Only really possible when the same object is being
#    used for multiple tests.  Sometimes the subject will vary based on
#    the describe blocks, in which case the subject block will be defined
#    inside it.

subject { @string = '' }

# 2) Specify the class or textual description for non-public classes and the method

describe String, '#<<' do

  # 3) Describe the starting object state and arguments

  describe 'given an empty string', 'when appending another string' do

    # 4) Setup the object state and arguments

    before { @other = 'Hello World' }

    # 5) Define the action the "it" blocks will test the behavior of

    action { subject << @other }

    # 6) Check the return value
    #   - make sure the object class is expected
    #   - make sure the object value is expected
    #     - when self is returned, make sure to use the equal_self matcher

    should_return_kind_of(String)
    should_return_subject
    should_return_expected_value { 'Hello World' }

    # (ALTERNATE STEP 6 -- when the action causes an exception)
    #
    # 6) Check the exception
    #   - make sure the exception class is expected
    #   - make sure the exception message is expected (only if within our control)

    should_raise_error(FooError, 'an error message')

    # 7) Check for side effects
    #   - Check @self to see how if it's changed
    #   - Check the arguments to see if they've been changed

    it 'should not change the other string' do
      lambda { action }.should_not change(@other, :to_s)
    end
  end
end


# concise form without instructional comments:

subject { @string = '' }

describe String, '#<<' do
  describe 'given an empty string', 'when appending another string' do
    before { @other = 'Hello World' }

    action { subject << @other }

    should_be_a_kind_of(String)
    should_equal_subject
    should_return_expected_value { 'Hello World' }
    should_raise_error(FooError, 'an error message')

    it 'should not change the other string' do
      lambda { action }.should_not change(@other, :to_s)
    end
  end
end