Interrogation about Spring MVC test API's model().attribute() method

Question

I am trying to test the following controller method using the Spring MVC test API:

@RequestMapping(value = "/preference/email", method = RequestMethod.GET, produces = "text/html")
public String emailForm(@ModelAttribute EmailInfo emailInfo, Model model, @CurrentMember Member member) {
    emailInfo.setEmail(member.getEmail());
    emailInfo.setActivated(member.isActivated());
    emailInfo.setToken(member.getToken());
    model.addAttribute("emailInfo", emailInfo);
    return "preference";
}

When I debug the following test method...

@Test
    public void shouldPopulateEmailInfo() throws Exception {
        when(currentMemberHandlerMethodArgumentResolver.supportsParameter(any(MethodParameter.class))).thenReturn(Boolean.TRUE);
        when(currentMemberHandlerMethodArgumentResolver.resolveArgument(any(MethodParameter.class), any(ModelAndViewContainer.class), any(NativeWebRequest.class), any(WebDataBinderFactory.class))).thenReturn(currentMember);
        mockMvc.perform(get("/preference/email"))//
                .andDo(print())//
                .andExpect(model().attribute("emailInfo.email", "currentMember@example.com"));//
    }

... I do see that "currentMember@example.com" is set on the email field of emailInfo.

However, I systematically get:

java.lang.AssertionError: Model attribute 'emailInfo.email' expected:<currentMember@example.com> but was:<null>
    at org.springframework.test.util.AssertionErrors.fail(AssertionErrors.java:60)
    at org.springframework.test.util.AssertionErrors.assertEquals(AssertionErrors.java:89)
    at org.springframework.test.web.servlet.result.ModelResultMatchers$2.match(ModelResultMatchers.java:68)
    at org.springframework.test.web.servlet.MockMvc$1.andExpect(MockMvc.java:141)
    at com.bignibou.tests.controller.preference.PreferenceControllerEmailManagementTest.shouldPopulateEmailInfo(PreferenceControllerEmailManagementTest.java:109)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:88)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

There is something I don't get with the Spring Mvc Test API.... Can anyone please help?

edit: Here is what I have come up with after taking into account the provided answer:

.andExpect(model().attribute("emailInfo", Matchers.hasProperty("email", Matchers.equalTo("currentMember@example.com"))));//

It works fine now.

Answer 1

As Sotirios pointed out, model().attribute("attributeName") wont allow you to navigate and it will use the whole thing as a name.

However you can use this method instead:

public <T> ResultMatcher attribute(final String name, final Matcher<T> matcher)

This will allow you to specify a Hamcrest matcher to match agains your attributes like:

.andExpect(model().attribute("emailInfo", hasProperty("email", is("currentMember@example.com"))))

Just make sure you have the Hamcrest library in your classpath and import it like:

import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*

Note: To import is specially important if you are using Groovy for your tests (Spock) as the method names in Hamcrest conflict with the Groovy standard library

Answer 2

Model attributes are String-key Object-value pairs. There is no expression resolving going on. When you do

model().attribute("emailInfo.email", "currentMember@example.com"));//

You are asking if there is a Model attribute with key emailInfo.email that has the specified value. The answer is obviously no since you don't have a Model attribute with such a key.

What you have is

model.addAttribute("emailInfo", emailInfo);

which is a Model attribute with key emailInfo that holds an object of type EmailInfo. You'll need to compare the email field of the EmailInfo object yourself.