request scoped beans in spring testing

Question

I would like to make use of request scoped beans in my app. I use JUnit4 for testing. If I try to create one in a test like this:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:spring/TestScopedBeans-context.xml" })
public class TestScopedBeans {
    protected final static Logger logger = Logger
            .getLogger(TestScopedBeans.class);

    @Resource
    private Object tObj;

    @Test
    public void testBean() {
        logger.debug(tObj);
    }

    @Test
    public void testBean2() {
        logger.debug(tObj);
    }

With the following bean definition:

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"&gt;
  <bean class="java.lang.Object" id="tObj" scope="request" />
 </beans>           

And I get:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'gov.nasa.arc.cx.sor.query.TestScopedBeans': Injection of resource fields failed; nested exception is java.lang.IllegalStateException: No Scope registered for scope 'request'
<...SNIP...>
Caused by: java.lang.IllegalStateException: No Scope registered for scope 'request'

So I found this blog that seemed helpful: http://www.javathinking.com/2009/06/no-scope-registered-for-scope-request/

But I noticed he uses AbstractDependencyInjectionSpringContextTests which seems to be deprecated in Spring 3.0. I use Spring 2.5 at this time, but thought it shouldn't be too hard to switch this method to use AbstractJUnit4SpringContextTests as the docs suggest (ok the docs link to the 3.8 version but I'm using 4.4). So I change the test to extend AbstractJUnit4SpringContextTests... same message. Same problem. And now the prepareTestInstance() method I want to override is not defined. OK, maybe I'll put those registerScope calls somewhere else... So I read more about TestExecutionListeners and think that would be better since I don't want to have to inherit the spring package structure. So I changed my Test to:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:spring/TestScopedBeans-context.xml" })
@TestExecutionListeners({})
public class TestScopedBeans {

expecting I would have to create a custom listener but I when I ran it. It works! Great, but why? I don't see where any of the stock listeners are registering request scope or session scope, and why would they? there's nothing to say I want that yet, this might not be a Test for Spring MVC code...

Answer 1

The test passes because it isn't doing anything :)

When you omit the @TestExecutionListeners annotation, Spring registers 3 default listeners, including one called DependencyInjectionTestExecutionListener. This is the listener responsible for scanning your test class looking for things to inject, including @Resource annotations. This listener tried to inject tObj, and fails, because of the undefined scope.

When you declare @TestExecutionListeners({}), you suppress the registration of the DependencyInjectionTestExecutionListener, and so the test never gets tObj injected at all, and because your test is not checking for the existence of tObj, it passes.

Modify your test so that it does this, and it will fail:

@Test
public void testBean() {
    assertNotNull("tObj is null", tObj);
}

So with your empty @TestExecutionListeners, the test passes because nothing happens.

Now, on to your original problem. If you want to try registering the request scope with your test context, then have a look at the source code for WebApplicationContextUtils.registerWebApplicationScopes(), you'll find the line:

beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());

You could try that, and see how you go, but there might be odd side-effects, because you're not really meant to do this in a test.

Instead, I would recommend rephrasing your test so that you don't need request scoped beans. This shouldn't be difficult, the lifecycle of the @Test shouldn't be any longer than the lifecycle of a request-scoped bean, if you write self-contained tests. Remember, there's no need to test the scoping mechanism, it's part of Spring and you can assume it works.