Spring4 MVC Unit test does not compile

问题:

I have strange behaviour when trying to compile sources after Spring 3.2.5 → 4.0.0 version update.

Faulty code snippet from ApplicationControllerTest.java (it is equivalent to code from documentation):

import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;
...
@Autowired
private WebApplicationContext wac;

private MockMvc               mockMvc;

@Before
public void setUp() {
    mockMvc = MockMvcBuilders.webAppContextSetup(wac).build();
}

Error:

COMPILATION ERROR : /C:/Development/.../war/src/test/java/org/.../web/controller/ApplicationControllerTest.java:[59,61] C:\Development\...\war\src\test\java\org\...\web\controller\ApplicationControllerTest.java:59: incompatible types; inferred type argument(s) java.lang.Object do not conform to bounds of type variable(s) B found : <B>org.springframework.test.web.servlet.setup.DefaultMockMvcBuilder<B> required: java.lang.Object

If one looks into MockMvcBuilders sources, one can see the difference:

Spring 4.0.0:

public static <B extends DefaultMockMvcBuilder<B>> DefaultMockMvcBuilder<B> webAppContextSetup(WebApplicationContext context) {
    return new DefaultMockMvcBuilder<B>(context);
}

Spring 3.2.5:

public static DefaultMockMvcBuilder<DefaultMockMvcBuilder<?>> webAppContextSetup(WebApplicationContext context) {
    return new DefaultMockMvcBuilder<DefaultMockMvcBuilder<?>>(context);
}

My attempts to make it compilable did not succeeded.

Actually Spring documentation says that framework should be Java 1.6.0_10 compatible. I use Java 1.6.0_45.

回答1:

I think the call of webAppContextSetup method now should be explicitly parameterized with the class of <B extends DefaultMockMvcBuilder<B>>. The obvious candidates are StandaloneMockMvcBuilder or simply DefaultMockMvcBuilder (though the later will generate a warning about unchecked or unsafe operations). So try this:

mockMvc = MockMvcBuilders.<StandaloneMockMvcBuilder>webAppContextSetup(wac).build();

回答2:

I had to tie the webAppContextSetup to the DefaultMockMvcBuilder in order to sort this problem out in my build (Java 1.6.0_65), and suppress the warnings that resulted from that.

@SuppressWarnings({"unchecked", "rawtypes"})
@Before
public void setUp()
{
   mockMvc = MockMvcBuilders.<DefaultMockMvcBuilder> webAppContextSetup(webApplicationContext).addFilter(springSecurityFilterChain).build();
}

As stated in another answer StandaloneMockMvcBuilder would work without warnings, if you are testing a stand alone controller rather than integration testing the full application context.

(Would have simply commented if I could have.)

回答3:

This has been fixed for Spring Framework 4.0.1.

See the following JIRA issue for details: https://jira.springsource.org/browse/SPR-11238