Java Extreme Programming Cookbook

Writing a Base Class for Your Tests

Problem

You want to reuse the same behavior in all of your tests without duplicating code.

Solution

Define common behavior in a subclass of junit.framework.TestCase and extend from your class, rather than directly extending TestCase.

Discussion

JUnit does not require that your tests directly extend TestCase. Instead, you can introduce new TestCase extensions for common behavior. You might want to ensure that some common initialization code is always executed before each of your tests. In that case, you might write something like this:

public abstract class MyAbstractTestCase extends TestCase {
    public MyAbstractTestCase(  ) {
        initializeApplicationProperties(  );
    }

    public MyAbstractTestCase(String testName) {
        super(testName);
        initializeApplicationProperties(  );
    }

    // initialize some custom application framework. Leave this method
    // protected so subclasses can customize.
    protected void initializeApplicationProperties(  ) {
        MyFramework.initialize("common/myappconfig.properties");
    }
}

Tests in your application can now extend MyAbstractTestCase and your framework initialization code will always be executed before the tests run.

Providing convenience methods is another reason why you might want to extend TestCase. We show this in the next recipe when we define a method to retrieve a Swing JFrame for graphical testing.