97 Things Every Java Programmer Should Know

Chapter 90. Use Testing to Develop Better Software Faster

Marit van Dijk

Testing your code will help you verify that your code does what you expect it to do. Tests will also help you to add, change, or remove functionality without breaking anything. But testing can have additional benefits.

Merely thinking about what to test will help to identify different ways the software will be used, discover things that are not clear yet, and better understand what the code should (and shouldn’t) do. Thinking about how to test these things before even starting your implementation could also improve your application’s testability and architecture. All of this will help you build a better solution before the tests and code are written.

Alongside the architecture of your system, think not only about what to test but also where to test. Business logic should be tested as close as possible to where it lives: unit tests to test small units (methods and classes), integration tests to test the integration between different components, contract tests to prevent breaking your API, etc.

Consider how to interact with your application in the context of a test, and use tools designed for that particular layer, from unit test (e.g., JUnit, TestNG), to API (e.g., Postman, REST-assured, RestTemplate), to UI (e.g., Selenium, Cypress).

Keep the goal of a particular test type in mind, and use the tools for that ...