Laurie Williams, Ben Smith, Sarah Heckman, and Lauren Hayward [Contact Authors]
CSC 326 - Software Engineering
Department of Computer Science
North Carolina State University

Back to Software Engineering Tutorials

Jazz Code Coverage is a component that measures the test coverage as your projects evolve.

Coverage is defined as a measure of the completeness of the set of test cases. This definition means that the more source code that is executed by your test cases the better. There are four types of coverage:

• Method coverage: what percentage of your methods have been called by your test cases?
• Statement coverage: what percentage of your statements have been run by your test cases?
• Decision/Branch coverage: what percentage of your decision points (if statements) have evaluated both true and false?
• Condition coverage: what percentage of your Boolean sub-expressions have been evaluated both true and false at a decision point?

For small programs, coverage is relatively easy to calculate by hand; however, for larger programs, the task is much more difficult. Coverage tools, like Jazz Code Coverage, help by automating the coverage process and providing readable reports.

Jazz Code Coverage may be used to calculate coverage for any launched application. We will be using it to calculate the coverage of our JUnit test cases (view the JUnit tutorial). You can run your JUnit test cases, and Jazz Code Coverage will generate the coverage report from the execution. Jazz Code Coverage provides overall, package, and file level information on statement coverage.

Jazz Code Coverage can be downloaded as an incubator from jazz.net. For more information on installing eclipse plugins, consult the tutorial on the subject.

1. For this tutorial, we will be using the CoffeeMaker project. Download the CoffeeMaker project from here or import the CoffeeMaker project that you used in the JUnit tutorial. Unzip the CoffeeMaker project to your home directory and import the project into Eclipse. Please see the Rational XDE and Eclipse Import/Export Guide for instructions on how to import a project into Eclipse.
2. In order to begin gathering code coverage information, you must first enable static code instrumentation.
In the Package Explorer view, right-click on your project and select Properties as shown in Figure 1.


Figure 1. Project Properties

3. Click the Java Coverage option in the left pane. Check the box Enable static code instrumentation. Static code instrumentation involves inserting probes throughout the software to monitor the software during run time (reference).
4. The settings automatically set 80% block coverage. In our class, we will try to achieve 80% line coverage as shown in Figure 2. (To learn more about the different types of coverage, view the Emma FAQ). Click OK.


Figure 2. Java Coverage

5. A dialog box will appear asking you if you would like to rebuild the project now. Click Yes.
6. Run your unit tests by right-clicking CoffeeMakerTest.java (located in CoffeeMaker > Src > unitttests > edu.csc.ncu.csc326.coffeemaker) and selecting Run As > JUnit Test. The Jazz Coverage tooling not only works with JUnit tests, it works with all Java-based launches supported by Eclipse! Section 3 will show you how to view your results!