Java™ Application Development on Linux - Dator

13.5 Writing Test Cases305Table 13.1 JUnit NamingClassMethodIn your original codeMyClassmyMethodIn your test caseMyClassTesttestMyMethodprepend the word “test” to the method name, and capitalize the now-no-longerfirstletter. Again, JUnit will use this naming convention, along withintrospection, to automatically derive the test names from the actual methodnames (more on that later, too). The naming conventions we’ve seen so far aresummarized in Table 13.1.Let’s take a quick look at the code. We import the framework for JUnittest cases, so that the compiler can resolve the names that deal with JUnit stuff.The TestCase class that we extend is part of that JUnit stuff. It’s an abstractclass that defines much of what we use for testing. We just fill in what we need.The TestCase class defines a method called setUp(). The setUp()method is called not just once, but before every test method is called. That wayyou can initialize variables and get into a known state before each test. Sinceit’s already defined in the TestCase class, we can override it (as in our example)to do what we want, or we can not include it in our class and get the defaultbehavior from TestCase (which is to do nothing).There is also a method named tearDown() which you can override if youneed to close things up at the end of a test case (e.g., close a database connection).As with setUp(), its default behavior, as defined in TestCase, is to donothing.The test case itself—the method where we will exercise our class—is calledtestCreateSub (since we want to test our createSub() method). Inside sucha method (and we could have more than one) we write code which uses theobjects in our application. Then at various junctures in the code we make assertionsabout the state of things—for example, this variable should be non-null,or this expression should have this particular value.Those assertions are, to our way of thinking, the tests. We’re testing to seeif the subaccount was created, or if the main account did, indeed, use up all ofits dollars in allocation to the subaccounts. But they are not what is called testsby JUnit. Rather, each individual method in a test class is considered a singletest. Such test methods are, typically, a collection of assertions surrounding theuse of a single (application) method. So in our example, the method