How to use PluginRegistry method of org.mockito.internal.configuration.plugins.Plugins class

How about

when( method-call ).thenReturn( value1, value2, value3 );

You can put as many arguments as you like in the brackets of thenReturn, provided they're all the correct type. The first value will be returned the first time the method is called, then the second answer, and so on. The last value will be returned repeatedly once all the other values are used up.

You could also Stub Consecutive Calls (#10 in 2.8.9 api). In this case, you would use multiple thenReturn calls or one thenReturn call with multiple parameters (varargs).

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import org.junit.Before;
import org.junit.Test;

public class TestClass {

    private Foo mockFoo;

    @Before
    public void setup() {
        setupFoo();
    }

    @Test
    public void testFoo() {
        TestObject testObj = new TestObject(mockFoo);

        assertEquals(0, testObj.bar());
        assertEquals(1, testObj.bar());
        assertEquals(-1, testObj.bar());
        assertEquals(-1, testObj.bar());
    }

    private void setupFoo() {
        mockFoo = mock(Foo.class);

        when(mockFoo.someMethod())
            .thenReturn(0)
            .thenReturn(1)
            .thenReturn(-1); //any subsequent call will return -1

        // Or a bit shorter with varargs:
        when(mockFoo.someMethod())
            .thenReturn(0, 1, -1); //any subsequent call will return -1
    }
}

Change this:

thenThrow(DataAccessException.class)

to

thenThrow(new DataAccessException("..."){ })

Example:

when(userSubModuleDao.findById(any(UserSubModuleId.class),eq(false))).thenThrow(new DataAccessException("..."){});

You can only pass a Class reference when that Exception type has a No-Arg constructor, and the Spring exception does not have one.

Turns out that Mockito, after "accepting" the first argument as Integer, fails to aceppt the second argument as String. The solution (after much debugging) is to cast the any() matcher in the test function to the corresponding class type:

@Test
public void testClass() throws Exception
{
    ResultSet rsResult = Mockito.mock(ResultSet.class);

    when(clsTableClass.getRecords(
            (Integer) any(),
            (String) any()).thenReturn(rsResult);
}

Now Mockito will match the parameters and the ResultSet will no longer return null.

In the setup of the unit test:

1. Get the same logger
2. Make it non-additive

3. Add an appender which remembers the messages in a list:

   public class TestAppender extends AppenderSkeleton {
       public List<String> messages = new ArrayList<String>();
   
       public void doAppend(LoggingEvent event) {
           messages.add( event.getMessage().toString() );
       }
   }
   

4. Add the appender to the logger

Now you can call your code. After the test, you will find all log messages in the list. Add the log level if you want (messages.add( event.getLevel() + " " + event.getMessage() );).

In tearDown(), remove the appender again and enable additivity.

Provided you are using Mockito version 1.9.0 or later, the best way to achieve what you want is like this:

@RunWith(MockitoJUnitRunner.class)
public class ServiceTest {

    @Mock
    private ServiceProxy proxy;

    @InjectMocks
    private Service service;

    @Test
    public void test() {
        assertNotNull(service);
        assertNotNull(proxy);
    }
}

First thing is the @RunWith(MockitoJUnitRunner.class) declaration which will cause @Mock and @InjectMocks annotation to work automatically without any explicit initialization. The second thing is that starting with Mockito 1.9.0 @InjectMocks annotation can use the Constructor injection mechanism which is the best option for your Service class.

Other options for @InjectMocks are Setter injection and Field injection (see docs BTW) but you'd need a no argument constructor to use them.

So summarizing - your code cannot work because:

• you are not using the MockitoJUnitRunner nor MockitoAnnotations.initMocks(this) so @Mock annotation takes no effect
• even if above were satisfied your example would fail because mockProxy would be initialized after the test is constructed and your service is tried to be initialized during the test class construction, hence it receives null mockProxy reference.

If for some reason you don't want to use @InjectMocks, the only way is to construct your Service object within the test method body or within the @Before annotated setUp method.

Caused by: org.mockito.exceptions.base.MockitoException: Checked exception is invalid for this method! Invalid: java.net.ConnectException: Test exception

As stated by the exception message (and told in comments), you have to throw a RestClientException, not a ConnectException:

Mockito.when(restOperations.exchange(
        Mockito.anyString(), Mockito.<HttpMethod>any(), Mockito.<HttpEntity<?>>any(),
        Mockito.<Class<UserByRoleHolder>>any())).thenThrow(new RestClientException("Test exception"));

You get this error message, because the method exchange declares no thrown exception and ConnectException is a checked exception (i.e. must be declared when thrown).

First, I would split your test into 2 separate tests, because you are testing 2 quite different scenarios:

@Test
public void testSuccessfulLogin() throws Exception {
    RequestBuilder requestBuilder = formLogin().user("test@tester.de").password("test");
    mockMvc.perform(requestBuilder).andExpect(redirectedUrl("/home")).andExpect(status().isFound());
}

@Test
public void testHomepageThrows500() throws Exception {

    // configure a mock service in the controller to throw an exception

    RequestBuilder requestBuilder = formLogin().user("test@tester.de").password("test");
    mockMvc.perform(requestBuilder).andExpect(redirectedUrl("/home")).andExpect(status().is5xxServerError());
}

Your first test is that of the successful login scenario.

The second test, as you've worded it in your question, is that where the home page (assuming a controller) returns a HTTP 500.
To get to the home page, you still need to login - it's not the act of logging on that generates the error, its the controller itself once you've logged on.
To make the controller return a HTTP 500 you are going to need to simulate some error. Without seeing your controller, I can only guess there is some service that is injected in. In your test you should be able to provide a mock of that, and then configure the mock to throw an exception.

You should be able to inject a mock something like this:

@RunWith(SpringJUnit4ClassRunner.class)
@WebMvcTest(HomeController.class)
public class HomeControllerIntegrationTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private YourService yourService;

And then within your test do something like the following (I'm using the BDD methods of mockito):

@Test
public void testHomepageThrows500() throws Exception {

    given(yourService.someMethod()).willThrow(new Exception("something bad happened");

    RequestBuilder requestBuilder = formLogin().user("test@tester.de").password("test");
    mockMvc.perform(requestBuilder).andExpect(redirectedUrl("/home")).andExpect(status().is5xxServerError());
}

Lenient mocks are what you want, if you can't just use a real UserKeychain.

Mockito.lenient().when(userKeychain.getUserStatus()).thenReturn(UserState.OK);
Mockito.lenient().when(otherUserKeychain.getUserStatus()).thenReturn(UserState.SUSPENDED);

Mockito is designed to replace systems where you can't use the real system in your test, particularly in systems that predictably invoke services instead of getting properties from data objects (or other idempotent actions). Because your system doesn't call those methods in a deterministic order, and because the calls aren't expensive and don't have side effects, I would recommend just going with the "lenient" option.

Imagine this case instead, where you are testing deleting user 1001:

when(userRpc.deleteUser(1001)).thenReturn(RPC_SUCCESS);
when(userRpc.deleteUser(1002)).thenReturn(RPC_SUCCESS);  // unnecessary

The test might pass if you ever delete the wrong user: Over-stubbing has masked a problem. Compare with this:

when(userRpc.fetchExpensiveUserDetails(1001)).thenReturn(user1001);
when(userRpc.fetchExpensiveUserDetails(1002)).thenReturn(user1002);  // unnecessary

Depending on what you're testing, this might be dangerous, but might not be so bad. Simulating a slow mobile network or with expensive data, maybe it is entirely against spec for you to fetch too much. However, in other cases, it may be acceptable. Finally, compare this case:

when(calculationResult.getRealComponent()).thenReturn(-1d);
when(calculationResult.getComplexComponent()).thenReturn(5);
when(calculationResult.getShortString()).thenReturn("-1 + 5i");

calculationResult looks an awful lot like a data object, and it is probably not a critical part of your test which of your methods to call or whether you're calling all of them. This is a case where Mockito's strict stubbing hinders you rather than helping you, and might be a case where you want to make some of those stubbings lenient. You might also choose to make the entire mock lenient, which particularly makes sense if you were to create a test helper method like stubCalculationResult(-1, 5) that prepared an entire object for you like that.

The only option better than that is to use a real object. In my example, if CalculationResult is an existing well-defined object, it may be lower risk overall to use a real one than to mock the behavior you believe at test-writing time to be correct. Similarly for your case, if you have access to a UserKeychain constructor that populates UserStatus etc, then it may be safer to use that in a test.

Though this might appear at first glance to be a slippery slope into turning a unit test into an integration test, I'd like to clarify that I'm recommending this only for data objects, which have no dependencies, and which ideally are immutable objects that have no methods with side-effects. If you use dependency injection, these are the type of single-implementation data holders that you would call new on rather than getting from your graph. This is also a good reason to separate your data objects so they are immutable and easy to construct, and to shift your services to consume those objects rather than giving methods to the data objects (favoring loginService.login(user) rather than user.login(loginService)).