I have a scoped dependency in my Activity and I want to test that activity with some mocks. I have read about different approach that suggest to replace Application component with a test component during the test, but what I want is to replace the Activity component.
For example, I want to test the Activity against mock presenter in my MVP setup.
I believe that replacing component by calling setComponent() on Activity will not work, because Activity dependencies already injected via field injection, so during the test, real object will be used.
How can I resolve this issue? What about Dagger1? Is it has the same issue?
Injecting the Component
First, you create a static class to act as a factory for your Activity. Mine looks a little like this:
public class ActivityComponentFactory {
private static ActivityComponentFactory sInstance;
public static ActivityComponentFactory getInstance() {
if(sInstance == null) sInstance = new ActivityComponentFactory();
return sInstance;
}
#VisibleForTesting
public static void setInstance(ActivityComponentFactory instance) {
sInstance = instance;
}
private ActivityComponentFactory() {
// Singleton
}
public ActivityComponent createActivityComponent() {
return DaggerActivityComponent.create();
}
}
Then just do ActivityComponentFactory.getInstance().createActivityComponent().inject(this); inside your Activities.
For testing, you can replace the factory in your method, before the Activity is created.
Providing mocks
As #EpicPandaForce's answer makes clear, doing this the officially-supported way currently involves a lot of boilerplate and copy/pasted code. The Dagger 2 team need to provide a simpler way of partially overriding Modules.
Until they do though, here's my unnoficial way: Just extend the module.
Let's say you want to replace your ListViewPresenter with a mock. Say you have a PresenterModule which looks like this:
#Module #ActivityScope
public class PresenterModule {
#ActivityScope
public ListViewPresenter provideListViewPresenter() {
return new ListViewPresenter();
}
#ActivityScope
public SomeOtherPresenter provideSomeOtherPresenter() {
return new SomeOtherPresenter();
}
}
You can just do this in your test setup:
ActivityComponentFactory.setInstance(new ActivityComponentFactory() {
#Override
public ActivityComponent createActivityComponent() {
return DaggerActivityComponent.builder()
.presenterModule(new PresenterModule() {
#Override
public ListViewPresenter provideListViewPresenter() {
// Note you don't have to use Mockito, it's just what I use
return Mockito.mock(ListViewPresenter.class);
}
})
.build();
}
});
...and it just works!
Note that you don't have to include the #Provides annotation on the #Override method. In fact, if you do then the Dagger 2 code generation will fail.
This works because the Modules are just simple factories - the generated Component classes take care of caching instances of scoped instances. The #Scope annotations are used by the code generator, but are irrelevant at runtime.
You cannot override modules in Dagger2 [EDIT: you can, just don't specify the #Provides annotation on the mock), which would obviously be the proper solution: just use the builder().somethingModule(new MockSomethingModule()).build() and be done with it!
If you thought mocking is not possible, then I would have seen two possible solutions to this problem. You can either use the modules to contain a pluggable "provider" that can have its implementation changed (I don't favor this because it's just too verbose!)
public interface SomethingProvider {
Something something(Context context);
}
#Module
public class SomethingModule {
private SomethingProvider somethingProvider;
public SomethingModule(SomethingProvider somethingProvider) {
this.somethingProvider = somethingProvider;
}
#Provides
#Singleton
public Something something(Context context) {
return somethingProvider.something(context);
}
}
public class ProdSomethingProvider implements SomethingProvider {
public Something something(Context context) {
return new SomethingImpl(context);
}
}
public class TestSomethingProvider implements SomethingProvider {
public Something something(Context context) {
return new MockSomethingImpl(context);
}
}
SomethingComponent somethingComponent = DaggerSomethingComponent.builder()
.somethingModule(new SomethingModule(new ProdSomethingProvider()))
.build();
Or you can bring the provided classes and injection targets out into their own "metacomponent" interface, which your ApplicationComponent and your TestApplicationComponent extend from.
public interface MetaApplicationComponent {
Something something();
void inject(MainActivity mainActivity);
}
#Component(modules={SomethingModule.class})
#Singleton
public interface ApplicationComponent extends MetaApplicationComponent {
}
#Component(modules={MockSomethingModule.class})
#Singleton
public interface MockApplicationComponent extends MetaApplicationComponent {
}
The third solution is to just extend the modules like in #vaughandroid 's answer. Refer to that, that is the proper way of doing it.
As for activity scoped components... same thing as I mentioned here, it's just a different scope, really.
I've found the following post that solves the problem:
http://blog.sqisland.com/2015/04/dagger-2-espresso-2-mockito.html
You need first to allow to modify the component of the activity:
#Override public void onCreate() {
super.onCreate();
if (component == null) {
component = DaggerDemoApplication_ApplicationComponent
.builder()
.clockModule(new ClockModule())
.build();
}
}
public void setComponent(DemoComponent component) {
this.component = component;
}
public DemoComponent component() {
return component;
}
And modify it in the test case
#Before
public void setUp() {
Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
DemoApplication app
= (DemoApplication) instrumentation.getTargetContext().getApplicationContext();
TestComponent component = DaggerMainActivityTest_TestComponent.builder()
.mockClockModule(new MockClockModule())
.build();
app.setComponent(component);
component.inject(this);
}
Related
I am creating UI tests. In order not to interact with the real server, I use MockWebServer. My goal is to emulate various server responses and see how the program as a whole will respond to them. At the moment, I don’t understand how to open screens that require authorization. Of course, I can write a code that will login to the authorization screen, and then go to the desired window. But this requires additional time to complete the test, and I would like to avoid this. I would not want to mocking classes, because I need to check the production version of the application. How can i do this?
For DI, I use Dagger-2. Here is the component code:
#Singleton
#Component(modules = {
AvatarsModule.class,
EncryptionModule.class,
ApiModule.class,
WalletsModule.class,
GeneralModule.class,
InteractorsModule.class,
PushNotificationsModule.class,
AppModule.class
})
public interface AppComponent {
#Component.Builder
interface Builder {
#BindsInstance
Builder context(Context context);
AppComponent build();
}
void inject(App app);
}
Here is the class code in which the authorization state is stored:
public class ApiWrapper {
private Api api;
private KeyPair keyPair;
private Account account;
...
public Flowable<Authorization> authorize(KeyPair tempKeyPair) {
return api
.authorize(tempKeyPair.getPublicKeyString().toLowerCase())
.subscribeOn(Schedulers.io())
.doOnNext((authorization -> {
this.account = authorization.getAccount();
this.keyPair = tempKeyPair;
}));
}
...
}
If anyone is still interested. I wrote an InstrumentationTestFacade class in which I put an ApiWrapper object using Dagger. Next, the InstrumentationTestFacade is injected into the Application object. Since the application object is not a singleton, there is no leak of responsibility in the main code, but from the test code you can access this facade using the following code:
Application application = (Application) InstrumentationRegistry.getInstrumentation().getTargetContext().getApplicationContext();
InstrumentationTestFacade facade = application.getInstrumentationTestFacade();
Below is an example:
public class InstrumentationTestFacade {
private LogoutInteractor logoutInteractor;
private SecurityInteractor securityInteractor;
private ApiWrapper apiWrapper;
public InstrumentationTestFacade(
LogoutInteractor logoutInteractor,
SecurityInteractor securityInteractor,
ApiWrapper apiWrapper
) {
this.logoutInteractor = logoutInteractor;
this.securityInteractor = securityInteractor;
this.apiWrapper = apiWrapper;
}
public void logout() {
logoutInteractor.logout();
}
public ApiWrapper getApiWrapper() {
return apiWrapper;
}
public SecurityInteractor getSecurityInteractor() {
return this.securityInteractor;
}
}
public class Application extends MultiDexApplication implements HasActivityInjector, HasServiceInjector {
...
#Inject
InstrumentationTestFacade instrumentationTestFacade;
#Override
public void onCreate() {
super.onCreate();
DaggerAppComponent
.builder()
.context(this)
.build()
.inject(this);
}
...
public InstrumentationTestFacade getInstrumentationTestFacade() {
return instrumentationTestFacade;
}
}
Using Dagger 2 for the first time with MVP.
I am stuck at a very simple implementation.
my presenter module takes View Interface in constructor along with context and data manager,I am confused in how to send activity context to the constructor for the view interface..
Any help will be highly appreciated..
Here is my code for App class:
public class App extends Application {
private static App app;
public SampleComponent getSc() {
return sc;
}
private SampleComponent sc;
public static App getApp() {
return app;
}
#Override
public void onCreate() {
super.onCreate();
app = this;
sc = DaggerSampleComponent.builder()
//.sampleModule(new SampleModule())
.presenterModule(new PresenterModule(new MainActivity(), getApplicationContext(), new ModelManager()))
.build();
}
}
Code for Presenter Module :
#Module
public class PresenterModule {
ShowCountContract.view v;
ModelManager mm;
Context c;
public PresenterModule(MainActivity m, Context c,
ModelManager mm) {
this.c = c;
this.mm = mm;
this.v = m;
}
#Singleton
#Provides
PresenterClass getPresentationClass() {
return new PresenterClass(mm, v);
}
}
To handle the Android context the best approach is to create an Application Component with an Application Module. This module should be responsible to provide objects that are common in the entire application, as the Context. And based on that component you can create subcomponents for each feature/activity/etc.
#Module
public class ApplicationModule {
private final Application application;
public ApplicationModule(Application application) {
this.application = application;
}
#Provides
Context provideContext() {
return application;
}
}
If you choose to work with just one component (what I do not recommend), your code for DaggerComponent creation will look like this:
DaggerSampleComponent.builder()
.applicationModule(new ApplicationModule(this))
.otherModule(new OtherModule())
.build();
Or you can use Component.Builder
As the Activity instance is created by the Android Framework, we cannot pass the View interface as a constructor parameter. The common way is to create such a method as attachView(ViewInterface) in your Presenter to be able to set an internal property.
Another thing you should change is to remove the Presenter's constructor from App and let the OtherModule be responsible for that:
#Module
public class OtherModule {
#Singleton
#Provides
PresenterClass getPresentationClass(Context ctx) {
return new PresenterClass(ctx, new ModelManager());
}
}
I recommend you to check this article where it goes deeper on Dagger explanation and even shows another Dagger's version that is directly thought to the Android environment.
Using Dagger2, what are the pros and cons of the 2 following implementations:
1)
public class MyReceiver extends BroadcastReceiver {
Something something;
#Override public void onReceive(Context context, Intent intent) {
something = ((MyApplication) context.getApplicationContext())
.getComponent().getSomething();
}
}
#Component
public interface MyComponent() {
Something getSomething();
}
2)
public class MyReceiver extends BroadcastReceiver {
#Inject Something something;
#Override public void onReceive(Context context, Intent intent) {
((MyApplication) context.getApplicationContext())
.getComponent().inject(this);
}
}
#Component
public interface MyComponent() {
void inject(MyReceiver myReceiver);
}
tl;dr Go for Option 2. #Inject your fields.
If your object can be created by injecting into the constructor (sample below), definitely go for Option 2, since you will not have to write any code other than marking the constructor to use with #Inject.
// object can just be injected without any additional modules
// since all dependencies can be satisfied
public class Something {
#Inject
public Something() {}
}
So to further answer the question let us concentrate on field / method injection.
Just using #Inject annotations will keep your code simpler. Option 2 will let you again just declare dependencies.
// dont't worry about where they come from
// or how they are created
#Inject
Something mSomething;
#Inject
Foo mFoo;
public void onCreate() {
((Application) context.getApplicationContext())
.getComponent().inject(this);
}
Also, for testing purposes you might want to override the injected fields, by just injecting the same object again with your TestComponent. This also is only possible with Option 2.
#Test
void someTest() {
// this is only possible with #Injected annotated fields
testComponent.inject(activityUnderTest);
}
But the first option!
The 1. Option will mostly be used to expose dependencies for dependent components, not to be confused with SubComponent components, which will always have full access to the parent graph.
#Component
public interface MyComponent() {
Something getSomething(); // exposes something
}
#Component(dependencies = {MyComponent.class})
public interface OtherComponent() {
// can access something in modules
}
Using Option 1 manually would mean to handle the dependency injection yourself by programmatically fetching dependencies from actual business code and writing harder to test code, which you are trying to avoid by using DI.
Is it possible I can use Dagger2 to inject a concrete implementation based on SDK version?
For example
// MediaPlayerComponent.class
#Component(modules = {MediaPlayerModule.class}
public interface MediaPlayerComponent
{
void inject(MediaPlayerUI ui)
}
// MediaPlayerUI.java
public class MediaPlayerUI
{
#Inject
public MediaPlayer mPlayer;
}
// GingerbreadMediaPlayer.java
public class GingerbreadMediaPlayer extends MediaPlayer {...}
// IceCreamSandwichMediaPlayer.java
public class IceCreamSandwichMediaPlayer extends MediaPlayer {...}
Yes, just decide which of both implementations should be returned in the MediaPlayerModule module in the concrete method annotated with #Provides, the one that returns a generic MediaPlayer.
Theoretically that's possible, I haven't done it before since I didn't have the need to but I think the following scenario would work:
You should have one parent ApplicationComponent that defines the needs of your app. Let's call it ApplicationComponent.
Now let's assume you want to have 2 different dependencies for API21 and above and for API below 21. You should create two components that inherits from your application component let's call them Application21Component and ApplicationBelow21Component.
For each of the two components you should have a different ApplicationModule that tells you application component how to get the dependencies needed
In your application class the body of "getComponent" function will be something similar to the following
public ApplicationComponent getComponent(){
if (mApplicationComponent == null) {
if (Build.VERSION.SDK_INT >= 21) {
mApplicationComponent = DaggerApplication21Component.builder()
.applicationModule(new ApplicationModule(this))
.build();
} else {
mApplicationComponent = DaggerApplicationBelow21Component.builder()
.applicationModule(new ApplicationModule(this))
.build();
}
}
return mApplicationComponent;
}
I'm a beginner with dependency injection.. specifically Dagger 2. I'm trying to figure out if/how I can do something like this:
#Inject
public void someMethodName(int someInteger, SomeObject dependency){
// do something with the dependency.
}
Or do I need to put that dependency in as a class var? any help with this would be greatly appreciated. also in this case the variable someInteger is not a dependency, but is being added by the caller... does that matter?
can I call it like this:
this.someMethodName(5);
android studio does not like the above calling method (I'm assuming because I'm doing something wrong)
You need to create component which is annotated by #Component.
The Component accepts module which provides dependencies.
Every component's name that you create starts with Dagger prefix, e.g. for MyComponent.
Let's look at the following example:
#Singleton
#Component(modules = DemoApplicationModule.class)
public interface ApplicationComponent {
void inject(DemoApplication application);
}
We created ApplicationComponent with single injection method. What we're saying is that we want to inject certain dependencies in DemoApplication.
Moreover, in the #Component annotations we specify module with provision methods.
This is like our module looks like:
#Module
public class DemoApplicationModule {
private final Application application;
public DemoApplicationModule(Application application) {
this.application = application;
}
#Provides #Singleton SomeIntegerHandler provideIntegerHandler() {
return new MySomeIntegerHandlerImpl();
}
}
What we're saying by creating DemoApplicationModule is that the module can provide desired dependencies in the injection place specified by our Component.
public class DemoApplication extends Application {
private ApplicationComponent applicationComponent;
#Inject SomeIntegerHandler handler;
#Override public void onCreate() {
super.onCreate();
applicationComponent = DaggerApplicationComponent.builder()
.demoApplicationModule(new DemoApplicationModule(this))
.build();
applicationComponent.inject(this);
handler.someMethodName(5);
}
}
See documentation what you kind of dependencies you can obtain. Additionally to obtaining just raw instance you can obtain Provider, Factory or Lazy instance.
http://google.github.io/dagger/api/latest/dagger/Component.html
You can also create scoped dependencis, the lifecycles of which depend on the lifecycle of injection places, like Activities or Fragments.
Hope I gave you the basic notion of what Dagger is.
YOU CAN USE SOME INTERFACE
public interface myDependence{
int myFunction(int value);
}
NOW IMPLEMENT IN YOU CLASS
public myClass implements MyDependence{
#Override
int myFunction(int value){
// do something
}
}