1. Intoduction to Unit Testing Using JUnit to structure Unit Testing SE-2030 Dr. Mark L. Hornick 1

2. How can you test your code? SE-2030 Dr. Mark L. Hornick 2

3. How can you test your app? Run the app with inputs that should produce a known output, and verify the actual output One problem with this approach may be that you can’t make your app accept “bad” inputs; thus you may not be able to force all possible if-then-else blocks of the app’s classes’ methods to execute Write a separate “test” program that is designed to exercise the classes and methods of the “production” app A problem with this might be gathering the results of the exercises and determining whether each one passed or failed. SE-2030 Dr. Mark L. Hornick 3

4. What is Unit Testing? Creating special-purpose test code that exercises specific classes of your application is called Unit Testing Such test code usually exercises one method at a time whenever possible. The tests usually include exercising the methods in “boundary conditions” by force- feeding the methods “bad” arguments, such as nulls. SE-2030 Dr. Mark L. Hornick 4

5. What is JUnit? JUnit is an open source Java testing framework used to write and run repeatable tests. It is built in to Eclipse. Like Ant, it can also run standalone JUnit is designed to automatically call “test” methods that in turn test the “real” code. It can compare actual results the “test” received from a real method vs. the results it expected, and report deviations. It does not guarantee that the methods it calls actually perform meaningful tests You must write meaningful tests You must write “enough” tests to cover all possible situations SE-2030 Dr. Mark L. Hornick 5

6. Demonstration SE-2030 Dr. Mark L. Hornick 6