RSpec

Short for 'Ruby specification'.

Benefits of testing:

Your code works.
You write less code! Specifically, you write only the code that's needed to pass your tests – nothing more.
Trying to break your tests gives you a good idea of how robust your code is and what everything's doing.

Getting started

Running rspec --init in the directory you want to test produces a lib folder with a spec_helper.rb file inside.

expect(lambda {...} ).to raise_error
# or:
expect{ ... }.to raise_error

If you don't use curly braces, the error kills the RSpec expect statement. The braces effectively allow RSpec to rescue the test from the error.

Methods you define in RSpec to assist you with tests.

def helper
	20.times{ dock.fill(bike) }
end

Now you can call helper in other tests.

Use 'shared examples'.

Group your tests by context. This makes them must clearer to read when they're displayed when running RSpec.
Mark a test as pending using xit instead of it.
Avoid "magic numbers", like 20.times.do. What does the 20 signify?