Why unit testing with Spring 3.1 WebMvcConfig fails?

Question

From Spring 3.1, we can use JavaConfig more easily thanks to @Enable* annotations.

So I made a WebConfig to set WebMvc configuration, and tried to test it. But if I extends WebMvcConfigurerAdapter or WebMvcConfigurationSupport with WebConfig the unit test fails because of lack of ServletContext. The code and messages look like below.

WebConfig.java

@Configuration @EnableWebMvc public class WebConfig extends WebMvcConfigurationSupport {} 

Test.java

@RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes=WebConfig.class) public class TestFail {     @Test     public void test() {} } 

Message

java.lang.IllegalStateException: Failed to load ApplicationContext     at org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:157)     at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109)     at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75) ... Caused by: java.lang.IllegalArgumentException: A ServletContext is required to configure default servlet handling     at org.springframework.util.Assert.notNull(Assert.java:112)     at org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer.<init>(DefaultServletHandlerConfigurer.java:54)     at org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport.defaultServletHandlerMapping(WebMvcConfigurationSupport.java:253)     at com.zum.news.comments.web.WebConfig$$EnhancerByCGLIB$$8bbfcca1.CGLIB$defaultServletHandlerMapping$10(<generated>)     at com.zum.news.comments.web.WebConfig$$EnhancerByCGLIB$$8bbfcca1$$FastClassByCGLIB$$19b86ad0.invoke(<generated>)     at net.sf.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:215)     at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:280)     at com.zum.news.comments.web.WebConfig$$EnhancerByCGLIB$$8bbfcca1.defaultServletHandlerMapping(<generated>)     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)     at java.lang.reflect.Method.invoke(Method.java:597)     at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:149)     ... 41 more 

How to unit test the WebConfig properly?

Edit

As Garcia said, this bug is fixed in Spring 3.2.0.RC1.

Just add @WebAppConfiguration annotation in the test class.

@RunWith(SpringJUnit4ClassRunner.class) @WebAppConfiguration @ContextConfiguration(classes=WebConfig.class) public class TestFail {     @Test     public void test() {} } 

Answer 1

As Guido mentioned previously, this has been solved as of 3.2. The following are the details of how to take advantage of the new test improvements. To ensure that a servlet context is loaded for your test, you need to annotate your test with @WebAppConfiguration and define AnnotationConfigWebContextLoader as your context loader, as below:

@RunWith(SpringJUnit4ClassRunner.class)     @WebAppConfiguration @ContextConfiguration(     classes = MyWebConfig.class,      loader = AnnotationConfigWebContextLoader.class) public class MyTest {     //... } 

Answer 2

If @EnableWebMvc annotation require ServletContext then I suggest to split your config to beans definitions which will be used in unit tests and other configuration which used by application and framework. In this case application will import both configs and unit tests will import only one.

BeansConfig.java:

@Configuration public class BeansConfig {     @Bean     MyBean myBean() {         return new MyBean()     } } 

WebConfig.java:

@Configuration @EnableWebMvc @Import(BeansConfig.class) public class WebConfig extends WebMvcConfigurationSupport {} 

TestFail.java:

@RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes=BeansConfig.class) public class TestFail {     @Test     public void test() {} }