WebAppConfiguration in Spring Tests – 春季测试中的WebAppConfiguration

最后修改: 2016年 8月 24日

1. Overview


In this article, we’ll explore the @WebAppConfiguration annotation in Spring, why we need it in our integration tests and also how can we configure it so that these tests actually bootstrap a WebApplicationContext.


2. @WebAppConfiguration


Simply put, this is a class-level annotation used to create a web version of the application context in the Spring Framework.


It’s used to denote that the ApplicationContext which is bootstrapped for the test should be an instance of WebApplicationContext.


A quick note about usage – we’ll usually find this annotation in integration tests because the WebApplicationContext is used to build a MockMvc object. You can find more information about integration testing with Spring here.

关于用法的简短说明 – 我们通常会在集成测试中发现这个注解,因为WebApplicationContext被用来构建MockMvc对象。您可以在这里找到有关Spring集成测试的更多信息。

3. Loading a WebApplicationContext


Starting with Spring 3.2, there is now support for loading a WebApplicationContext in integration tests:

从Spring 3.2开始,现在支持在集成测试中加载WebApplicationContext

@ContextConfiguration(classes = WebConfig.class)
public class EmployeeControllerTest {

This instructs the TestContext framework that a WebApplicationContext should be loaded for the test.


And, in the background a MockServletContext is created and supplied to our test’s WebApplicationContext by the TestContext framework.


3.1. Configuration Options


By default, the base resource path for the WebApplicationContext will be set to “file:src/main/webapp”, which is the default location for the root of the WAR in a Maven Project.


However, we can override this by simply providing an alternate path to the @WebAppConfiguration annotation:



We can also reference a base resource path from the classpath instead of the file system:



3.2. Caching


Once the WebApplicationContext is loaded it will be cached and reused for all subsequent tests that declare the same unique context configuration within the same test suite.


For further details on caching, you can consult the Context caching section of the reference manual.


4. Using @WebAppConfiguration in Tests


Now that we understand why do we need to add the @WebAppConfiguration annotation in our test classes, let’s see what happens if we miss adding it when we are using a WebApplicationContext.


// @WebAppConfiguration omitted on purpose
@ContextConfiguration(classes = WebConfig.class)
public class EmployeeTest {

    private WebApplicationContext webAppContext;
    private MockMvc mockMvc;

    public void setup() {
        mockMvc = MockMvcBuilders.webAppContextSetup(webAppContext).build();

Notice that we commented out the annotation to simulate the scenario in which we forget to add it. Here it’s easy to see why the test will fail when we run the JUnit test: we are trying to autowire the WebApplicationContext in a class where we haven’t set one.


A more typical example however is a test that uses a web-enabled Spring configuration; that’s actually enough to make the test break.


Let’s have a look:


// @WebAppConfiguration omitted on purpose
@ContextConfiguration(classes = WebConfig.class)
public class EmployeeTestWithoutMockMvc {

    private EmployeeController employeeController;


Even though the above example isn’t autowiring a WebApplicationContext it will still fail because it’s trying to use a web-enabled configuration – WebConfig:

即使上面的例子没有自动连接WebApplicationContext,它仍然会失败,因为它试图使用一个支持网络的配置 – WebConfig

public class WebConfig implements WebMvcConfigurer {

The annotation @EnableWebMvc is the culprit here – that will basically require a web enabled Spring context, and without it – we’ll see the test fail:


Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: 
  No qualifying bean of type [javax.servlet.ServletContext] found for dependency: 
    expected at least 1 bean which qualifies as autowire candidate for this dependency. 

Dependency annotations: 
    at o.s.b.f.s.DefaultListableBeanFactory
    at o.s.b.f.s.DefaultListableBeanFactory
    at o.s.b.f.s.DefaultListableBeanFactory
    at o.s.b.f.a.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement
    ... 43 more

So that’s the problem that we’re easily fixing by adding the @WebAppConfiguration annotation to our tests.


5. Conclusion


In this article we showed how we can let the TestContext framework to load a WebApplicationContext into our integration tests just by adding the annotation.


Finally, we looked at the examples that even though if we add the @ContextConfiguration to the test, this won’t be able to work unless we add the @WebAppConfiguration annotation.


The implementation of the examples in this article are available in our repository on GitHub.