Getting Started with Unit Tests

A unit test tests one unit of code. In Java terms, this usually means that a unit test tests a single Java class. The test should run quickly, so you know whether there are any problems as soon as possible.

A unit test is a separate Java class designed just for testing. You should write separate test methods for each part of the original class you want to test. Typically, the more fine-grained the test, the better.

Sometimes, due to necessity, a unit test will test more than one class. That's OK and not something to worry about. In general, though, you want to concentrate on writing separate tests for each class in your Java application.

Note

Writing your Java classes so that they are easy to test will improve your code. You'll have better code organization, clearer code, and better quality as a result.

Integration tests, on the other hand, test a part of the entire system, including external dependencies. For example, a unit...