Mockito, JUnit and Spring

Honestly I am not sure if I really understand your question :P I will try to clarify as much as I can, from what I get from your original question:

First, in most case, you should NOT have any concern on Spring. You rarely need to have spring involved in writing your unit test. In normal case, you only need to instantiate the system under test (SUT, the target to be tested) in your unit test, and inject dependencies of SUT in the test too. The dependencies are usually a mock/stub.

Your original suggested way, and example 2, 3 is precisely doing what I am describing above.

In some rare case (like, integration tests, or some special unit tests), you need to create a Spring app context, and get your SUT from the app context. In such case, I believe you can:

1) Create your SUT in spring app ctx, get reference to it, and inject mocks to it

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration("test-app-ctx.xml")public class FooTest {    @Autowired    @InjectMocks    TestTarget sut;    @Mock    Foo mockFoo;    @Before    /* Initialized mocks */    public void setup() {        MockitoAnnotations.initMocks(this);    }    @Test    public void someTest() {         // ....    }}

or

2) follow the way described in your link Spring Integration Tests, Creating Mock Objects. This approach is to create mocks in Spring's app context, and you can get the mock object from the app ctx to do your stubbing/verification:

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration("test-app-ctx.xml")public class FooTest {    @Autowired    TestTarget sut;    @Autowired    Foo mockFoo;    @Test    public void someTest() {         // ....    }}

Both ways should work. The main difference is the former case will have the dependencies injected after going through spring's lifecycle etc. (e.g. bean initialization), while the latter case is injected beforehands. For example, if your SUT implements spring's InitializingBean, and the initialization routine involves the dependencies, you will see the difference between these two approach. I believe there is no right or wrong for these 2 approaches, as long as you know what you are doing.

Just a supplement, @Mock, @Inject, MocktoJunitRunner etc are all unnecessary in using Mockito. They are just utilities to save you typing the Mockito.mock(Foo.class) and bunch of setter invocations.

Your question seems to be asking about which of the three examples you have given is the preferred approach.

Example 1 using the Reflection TestUtils is not a good approach for Unit testing. You really don't want to be loading the spring context at all for a unit test. Just mock and inject what is required as shown by your other examples.

You do want to load the spring context if you want to do some Integration testing, however I would prefer using @RunWith(SpringJUnit4ClassRunner.class) to perform the loading of the context along with @Autowired if you need access to its' beans explicitly.

Example 2 is a valid approach and the use of @RunWith(MockitoJUnitRunner.class) will remove the need to specify a @Before method and an explicit call to MockitoAnnotations.initMocks(this);

Example 3 is another valid approach that doesn't use @RunWith(...). You haven't instantiated your class under test HelloFacadeImpl explicitly, but you could have done the same with Example 2.

My suggestion is to use Example 2 for your unit testing as it reduces the code clutter. You can fall back to the more verbose configuration if and when you're forced to do so.

The introduction of some new testing facilities in Spring 4.2.RC1 lets one write Spring integration tests that don't rely on the SpringJUnit4ClassRunner. Check out this part of the documentation.

In your case you could write your Spring integration test and still use mocks like this:

@RunWith(MockitoJUnitRunner.class)@ContextConfiguration("test-app-ctx.xml")public class FooTest {    @ClassRule    public static final SpringClassRule SPRING_CLASS_RULE = new SpringClassRule();    @Rule    public final SpringMethodRule springMethodRule = new SpringMethodRule();    @Autowired    @InjectMocks    TestTarget sut;    @Mock    Foo mockFoo;    @Test    public void someTest() {         // ....    }}