Testing with Dagger, Retrofit & MockWebServer gists

build.gradle

compile 'com.squareup.retrofit:retrofit:1.6.1'
compile 'com.squareup.okhttp:okhttp:2.0.0'
compile 'com.squareup.okhttp:okhttp-urlconnection:2.0.0'
compile 'com.squareup.okhttp:mockwebserver:2.0.0'
compile 'com.squareup.dagger:dagger:1.2.+'
provided 'com.squareup.dagger:dagger-compiler:1.2.+'

androidTestCompile 'org.mockito:mockito-core:1.9.5'
androidTestCompile 'com.google.dexmaker:dexmaker:1.1'
androidTestCompile 'com.google.dexmaker:dexmaker-mockito:1.1'

DaggerHelper.java

/**
 * Allows easy swapping of production and test modules to satisfy Dagger dependencies
 */
public class DaggerHelper
{
    //DAGGER
    private static ObjectGraph sObjectGraph;

    private static final List<Object> productionModules;

    static
    {
        productionModules = new ArrayList<Object>();
        productionModules.add(new ServerApiModule());
    }

    /**
     * Init the dagger object graph with production modules
     */
    public synchronized static void initProductionModules()
    {
        initWithModules(productionModules);
    }

    /**
     * If passing in test modules make sure to override = true in the @Module annotation
     */
    public synchronized static void initWithTestModules(Object... testModules)
    {
        initWithModules(getModulesAsList(testModules));
    }

    /**
     * Will create a new object graph and therefore reset any previous modules set
     *
     * @param modules
     */
    private synchronized static void initWithModules(List<Object> modules)
    {
        sObjectGraph = ObjectGraph.create(modules.toArray());
    }

    private synchronized static List<Object> getModulesAsList(Object... extraModules)
    {
        List<Object> allModules = new ArrayList<Object>();
        allModules.addAll(productionModules);
        allModules.addAll(Arrays.asList(extraModules));
        return allModules;
    }

    /**
     * Dagger convience method - will inject the fields of the passed in object
     */
    public synchronized static void inject(Object object)
    {
        sObjectGraph.inject(object);
    }
}

ExampleTest.java

@Override
protected void tearDown() throws Exception
{
    super.tearDown();
    DaggerHelper.initProductionModules(); //make sure any mock web server module overrides are removed
}

/**
 * Allows a MockWebServer instance to be scripted for the api service
 */
@Module(
    overrides = true,
    library = true
)
public class TestServerApiModule
{
    private final MockWebServer mMockWebServer;

    public TestServerApiModule()
    {
        mMockWebServer = new MockWebServer();
        mMockWebServer.play();
    }

    @Provides
    MockWebServer providerMockWebServer()
    {
        return mMockWebServer;
    }

    @Provides
    ServerApi providerServerApi()
    {
        RestAdapter restAdapter = new RestAdapter.Builder()
                .setEndpoint(mMockWebServer.getUrl("/").toString())
                .build();

        ServerApi api = restAdapter.create(ServerApi.class);
        return api;
    }
}

public void testSomething()
{
    TestServerApiModule testServerApiModule = new TestServerApiModule();
    DaggerHelper.initWithTestModules(testServerApiModule);

    //script MockWebServer
    MockResponse mockResponse = new MockResponse().setResponseCode(500);
    testServerApiModule.getMockWebServer().enqueue(mockResponse);

    //test something    
    new SomeClassThatUsesTheApi().doSomething();
    ...
    <assert something>    
}

ServerApiModule.java

@Module(
    injects = Example.class
)
public class ServerApiModule
{
    @Provides
    ServerApi providerServerApi()
    {
        RestAdapter restAdapter = new RestAdapter.Builder()
                .setEndpoint(ServerConst.API_ENDPOINT)
                .build();

        ServerApi api = restAdapter.create(ServerApi.class);
        return api;
    }
}