When a method is long and complex, it is harder to test. You can make it easier by extracting methods
# Check if results have been cached. # No results in the cache, so check the database. # Count passing and failing tests. This method is difficult to test because it not only relies on a database, but also on a cache. In addition, it performs some post processing of the retrieved results. The first hint that this method could use refactoring is the abundance of comments. Extracting sections of code into well-named methods reduces the original method's complexity. When complexity is reduced, comments often become unnecessary. For example, consider the following:
Now, tests can focus on each individual piece of the original method by testing each extracted method. This has the added benefit of making the code more readable and easier to maintain.
(Note: Method extraction can be done for you automatically in Python by the open-source refactoring browser BicycleRepairMan, and in Java by several IDEs, including IntelliJ IDEA and Eclipse.)
Remember to download this episode of Testing on the Toilet and post it in your office.
I find it interesting that the fallacy of strong method names means that one does not need to use comments. Comments can and should be used to express intent, while code only expresses what the developer has done. When testing code what the code does is less important than the intent of the code.
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