I’ve just watched this presentation by Sandro Mancuso about Testing and Refactoring Legacy Code.

In this video the trip-service-kata is used.

These are notes to myself taken while watching the video:

• Wrap code with tests before modifying it. If the code is not covered by tests perform IDE auto refactorings only.
• Start testing from the lower nesting level to the deepest.
• Start refactoring from the deepest nesting level to the shorter.
• In the case of static methods, singletons or instances being created inside a method: create seams to make code testable. Seams can be overriden in order to obtain an intermediate testable class.
• When working with legacy code use code coverage in order to verify that your tests cover the code they are created for.
• Use builders to make tests more readable.
• Refactor staying on the green side of red-green-refactor cycle as much as you can.
• Try to convert conditionals to guards.
• Initially get rid of variables whenever possible without considering potential performance issues caused by calling methods multiple times. Variables can be reintroduced later on if needed.
• Your code should reflect the language in your tests if possible.
• The language in your tests and code should be the domain language.
• If the design is wrong - when adding tests we are perpetuating the wrong design!
• Wrap static methods in instance methods. In your code base start replacing static calls to instance calls, until the static call is not used anymore: then you can get rid of the static method.