9.2 Unit testing

9.2 Unit testing
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Dependency Injection should make your code less dependent on the container than it would be with traditional Java EE development. The POJOs that make up your application should be testable in JUnit or TestNG tests, with objects simply instantiated using the new operator, without Spring or any other container. You can use mock objects (in conjunction with other valuable testing techniques) to test your code in isolation. If you follow the architecture recommendations for Spring, the resulting clean layering and componentization of your codebase will facilitate easier unit testing. For example, you can test service layer objects by stubbing or mocking DAO or Repository interfaces, without needing to access persistent data while running unit tests.

True unit tests typically run extremely quickly, as there is no runtime infrastructure to set up. Emphasizing true unit tests as part of your development methodology will boost your productivity. You may not need this section of the testing chapter to help you write effective unit tests for your IoC-based applications. For certain unit testing scenarios, however, the Spring Framework provides the following mock objects and testing support classes.

9.2.1 Mock objects

9.2.1.1 JNDI

The org.springframework.mock.jndi package contains an implementation of the JNDI SPI, which you can use to set up a simple JNDI environment for test suites or stand-alone applications. If, for example, JDBC DataSources get bound to the same JNDI names in test code as within a Java EE container, you can reuse both application code and configuration in testing scenarios without modification.

9.2.1.2 Servlet API

The org.springframework.mock.web package contains a comprehensive set of Servlet API mock objects, targeted at usage with Spring's Web MVC framework, which are useful for testing web contexts and controllers. These mock objects are generally more convenient to use than dynamic mock objects such as EasyMock or existing Servlet API mock objects such as MockObjects.

9.2.1.3 Portlet API

The org.springframework.mock.web.portlet package contains a set of Portlet API mock objects, targeted at usage with Spring's Portlet MVC framework.

9.2.2 Unit testing support classes

9.2.2.1 General utilities

The org.springframework.test.util package contains ReflectionTestUtils, which is a collection of reflection-based utility methods. Developers use these methods in unit and integration testing scenarios in which they need to set a non-public field or invoke a non-public setter method when testing application code involving, for example:

ORM frameworks such as JPA and Hibernate that condone private or protected field access as opposed to public setter methods for properties in a domain entity.
Spring's support for annotations such as @Autowired and @Resource, which provides dependency injection for private or protected fields, setter methods, and configuration methods

9.2.2.2 Spring MVC

The org.springframework.test.web package contains ModelAndViewAssert, which you can use in combination with JUnit 4+, TestNG, and so on for unit tests dealing with Spring MVC ModelAndView objects.

	Unit testing Spring MVC Controllers
	To test your Spring MVC `Controller`s, use `ModelAndViewAssert` combined with `MockHttpServletRequest`, `MockHttpSession`, and so on from the `org.springframework.mock.web` package.