1 JUnit jump-start

This chapter covers

  • Understanding JUnit
  • Installing JUnit
  • Writing your first tests
  • Running tests

Never in the field of software development was so much owed by so many to so few lines of code.

--Martin Fowler

All code needs to be tested. During development, the first thing we do is run our own programmer’s acceptance test. We code, compile, and run. When we run, we test. The test may just consist of clicking a button to see whether it brings up the expected menu or looking at a result to compare it with the expected value. Nevertheless, every day, we code, we compile, we run, and we test.

When we test, we often find issues, especially during early runs. So we code, compile, run, and test again.

Most of us quickly develop a pattern for our informal tests: add a record, view a record, edit a record, and delete a record. Running a little test suite like this by hand is easy enough to do, so we do it--over and over again.

Some programmers like doing this type of repetitive testing. It can be a pleasant break from deep thought and hardcoding. When our little click-through tests finally succeed, we have a real feeling of accomplishment (“Eureka! I found it!”).

Other programmers dislike this type of repetitive work. Rather than run the tests by hand, they prefer to create a small program that runs the tests automatically. Play-testing code is one thing; running automated tests is another.

1.1 Proving that a program works

1.2 Starting from scratch

1.2.1 Understanding unit testing frameworks

1.2.2 Adding unit tests

1.3 Setting up JUnit

1.4  Testing with JUnit