Test-Driven Development Using StrutsTestCase

StrutsTestCase is a powerful and easy-to-use testing framework for Struts actions. Using Struts and then StrutsTestCase, in combination with traditional JUnit tests, will give you a very high level of test coverage and increase your product reliability accordingly.

StrutsTestCase is a test framework based on JUnit for testing Struts actions. If you use Struts, it can provide an easy and efficient manner for testing the Struts action classes of your application.

Typical J2EE applications are built in layers, as illustrated in Figure 1.

• The DAO layer encapsulates database access. Hibernate mapping and object classes, Hibernate queries, entity EJBs, or some other entity-relation persistence technology may be found here.
• The business layer contains more high-level business services. Ideally, the business layer will be relatively independent of the database implementation. Session EJBs are often used in this layer.
• The presentation layer involves displaying application data for the user and interpreting the user requests. In a Struts application, this layer typically uses JSP/JSTL pages to display data and Struts actions to interpret the user queries.
• The client layer is basically the web browser running on the user's machine. Client-side logic (for example, JavaScript) is sometimes placed here, though it is hard to test efficiently.

Figure 1. Typical J2EE architecture

The DAO and business layers can be tested either using classic JUnit tests or some of the various JUnit extensions, depending on the architectural details. DbUnit is a good choice for database unit testing--see Andrew Glover's "Effective Unit Testing with DbUnit" for more on DbUnit.

On the other hand, testing Struts actions has always been difficult. Even when business logic is well confined to the business layer, Struts actions generally contain important data validation, conversion, and flow control code. Not testing the Struts actions leaves a nasty gap in code coverage. StrutsTestCase lets you fill this gap.

Unit testing the action layer also provides other benefits:

• The view and control layers tend to be better thought out and are often simpler and clearer.
• Refactoring the action classes is easier.
• It helps to avoid redundant and unused action classes.
• The test cases help document the action layer, which can help when writing the JSP screens.

Introducing StrutsTestCase

The StrutsTestCase project provides a flexible and convenient way to test Struts actions from within the JUnit framework. It lets you do white-box testing on your Struts actions by setting up request parameters and checking the resulting Request or Session state after the action has been called.

StrutsTestCase allows either a mock-testing approach, where the framework simulates the web server container, or an in-container approach, where the Cactus framework is used to run the tests from within the server container (for example, Tomcat). In general, I prefer the mock-testing approach because it is more lightweight and runs faster, and thus allows a tighter development cycle.

All StrutsTestCase unit test classes are derived from either MockStrutsTestCase for mock testing, or from CactusStrutsTestCase for in-container tests. We'll concentrate on mock testing here, as it requires less setup and is faster to run.