In part 2 of this series, we write actual tests for the context structure we discovered in part 1. Along the way, we'll verify that each test is actually testing something by breaking the code in a very small way to see it fail. (Ideally, this would cause an assertion failure each time; some erroring tests are allowed to slip by for speed's sake.) (The respond_to block used in this screencast could be replaced with `post :foo, :id => 12, :format => :js` in the test, leaving the production code unchanged.)