Pragmatic Unit Testing in Java with JUnit, 3rd Edition

The Parts of an Individual Test

A handful of chapters ago (see ​Scannability: Arrange—Act—Assert​), you learned how AAA provides a great visual mnemonic to help readers quickly understand the core parts of a test.

Some developers refer to a “four-phase test,”^[22] where each test can be broken into (wait for it) four parts or phases:

• Set up state/data in what’s sometimes called a fixture. Think of a fixture as the context in which a test runs—its world, so to speak. The fixture is managed for you by JUnit; you’ll learn more about that in this chapter as part of the JUnit test execution lifecycle.

• Interact with the system to execute what you want to verify.

• Do the verification (assert).

• Tear down the fixture—clean up any side effects, if necessary. ...