Creating unitary tests in Spring 3

Question

I'm starting on testing applications in general and I want to create several tests to learn Mockito in Spring. I've been reading several information but I have some general doubts I'd like to ask.

1. I have seen come Mockito tests and they annotate the test of the class with: @RunWith(MockitoJUnitRunner.class) while in the Spring documentation it is used @RunWith(SpringJUnit4ClassRunner.class). I don't know what's the difference between them and which one should I use for a Spring application where tests use Mockito.
2. As I haven't seen any real application that has test I'd like to know typical test that a developer would do. For example in a typical CRUD application for users (users can be created, updated...) can anyone a usual test that it would be done.

Thanks.

Answer 1

@RunWith(MockitoJUnitRunner.class)

With this declaration you are suppose to write a unit test. Unit tests are exercising a single class mocking all dependencies. Typically you will inject mocked dependencies declared like this in your test case:

@Mock
private YourDependency yourDependencyMock;

---

@RunWith(SpringJUnit4ClassRunner.class)

Spring runner is meant for integration test (component test?) In this type of tests you are exercising a whole bunch of classes, in other words you are testing a single class with real dependencies (testing a controller with real services, DAOs, in-memory database, etc.)

You should probably have both categories in your application. Althought it is advices to have more unit tests and only few smoke integration tests, but I often found myself more confident writing almost only integration tests.

As for your second question, you should have:

• unit tests for each class (controller, services, DAOs) separately with mocked all other classes

• integration tests for a whole single CRUD operation. For instance creating a user that exercises controller, service, DAO and in-memory database.