When refactoring tests, you end up moving critical assertion logic outside of the test method. This can cause our tests to fail in the wrong spot. This becomes worse if multiple methods share test logic. When a test fails you want to know exactly where the failure occurred. By leveraging #file and #line expression literals we can move the failure back to where it should be, within the test method. We will also see how we can continue to use expectations outside of a test instance.
This is a companion discussion topic for the original entry at https://nsscreencast.com/episodes/337-refactoring-tests-part-1