Guice injections

Any guice bean could be injected directly into a test field:

@Inject
SomeBean bean

This will work even for not declared (in guice modules) beans (JIT injection will occur).

To better understand injection scopes look the following test:

// one application instance started for all test methods
@TestGuiceyApp(AutoScanApplication.class)
@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
public class InjectionScopeTest {

    // new instance injected on each test
    @Inject
    TestBean bean;

    // the same context used for all tests (in class), so the same bean instance inserted before each test
    @Inject
    TestSingletonBean singletonBean;

    @Test
    @Order(1)
    public void testInjection() {
        bean.value = 5;
        singletonBean.value = 15;

        Assertions.assertEquals(5, bean.value);
        Assertions.assertEquals(15, singletonBean.value);

    }

    @Test
    @Order(2)
    public void testSharedState() {

        Assertions.assertEquals(0, bean.value);
        Assertions.assertEquals(15, singletonBean.value);
    }

    // bean is in prototype scope
    public static class TestBean {
        int value;
    }

    @Singleton
    public static class TestSingletonBean {
        int value;
    }
}

Note

Guice AOP will not work on test methods (because test instances are not created by guice).

Parameter injection

Any declared guice bean may be injected as test method parameter:

@Test
public void testSomthing(DummyBean bean) 

(where DummyBean is manually declared in some module or requested as a dependency (JIT-instantiated) during injector creation).

For unknown beans injection (not declared and not used during startup) special annotation must be used:

@Test
public void testSomthing(@Jit TestBean bean) 

Info

Additional annotation required because you may use other junit extensions providing their own parameters, which guicey extension should not try to handle. That's why not annotated parameters verified with existing injector bindings.

Qualified and generified injections will also work:

@Test
public void testSomthing(@Named("qual") SomeBean bean,
                         TestBean<String> generifiedBean,
                         Provider<OtherBean> provider) 

Also, there are special objects available as parameters:

• Application or exact application class (MyApplication)
• ObjectMapper
• ClientSupport application web client helper
• DropwizardTestSupport test support object used internally
• ExtensionContext junit extension context

Note

Parameter injection will work on test methods as well as lifecyle methods (beforeAll, afterEach etc.)

Example:

@TestDropwizardApp(AutoScanApplication.class)
public class ParametersInjectionDwTest {

    public ParametersInjectionDwTest(Environment env, DummyService service) {
        Preconditions.checkNotNull(env);
        Preconditions.checkNotNull(service);
    }

    @BeforeAll
    static void before(Application app, DummyService service) {
        Preconditions.checkNotNull(app);
        Preconditions.checkNotNull(service);
    }

    @BeforeEach
    void setUp(Application app, DummyService service) {
        Preconditions.checkNotNull(app);
        Preconditions.checkNotNull(service);
    }

    @AfterEach
    void tearDown(Application app, DummyService service) {
        Preconditions.checkNotNull(app);
        Preconditions.checkNotNull(service);
    }

    @AfterAll
    static void after(Application app, DummyService service) {
        Preconditions.checkNotNull(app);
        Preconditions.checkNotNull(service);
    }

    @Test
    void checkAllPossibleParams(Application app,
                                AutoScanApplication app2,
                                Configuration conf,
                                TestConfiguration conf2,
                                Environment env,
                                ObjectMapper mapper,
                                Injector injector,
                                ClientSupport client,
                                DropwizardTestSupport support,
                                DummyService service,
                                @Jit JitService jit) {
        assertNotNull(app);
        assertNotNull(app2);
        assertNotNull(conf);
        assertNotNull(conf2);
        assertNotNull(env);
        assertNotNull(mapper);
        assertNotNull(injector);
        assertNotNull(client);
        assertNotNull(support);
        assertNotNull(service);
        assertNotNull(jit);
        assertEquals(client.getPort(), 8080);
        assertEquals(client.getAdminPort(), 8081);
    }

    public static class JitService {

        private final DummyService service;

        @Inject
        public JitService(DummyService service) {
            this.service = service;
        }
    }
}

Tip

DropwizardTestSupport and ClientSupport objects are also available with a static calls (in the same thread):

DropwizardTestSupport support = TestSupport.getContext();
ClientSupport client = TestSupport.getContextClient();