DaggerMock
A JUnit rule to easily override Dagger 2 objects
Override an object managed by Dagger 2 is not easy, you need to define a TestModule and, if you want to inject your test object, a TestComponent.
Using a DaggerMockRule it's possible to override easily the objects defined in a Dagger module:
public class MainServiceTest {
@Rule public DaggerMockRule<MyComponent> mockitoRule = new DaggerMockRule<>(MyComponent.class, new MyModule())
.set(new DaggerMockRule.ComponentSetter<MyComponent>() {
@Override public void setComponent(MyComponent component) {
mainService = component.mainService();
}
});
@Mock RestService restService;
@Mock MyPrinter myPrinter;
MainService mainService;
@Test
public void testDoSomething() {
when(restService.doSomething()).thenReturn("abc");
mainService.doSomething();
verify(myPrinter).print("ABC");
}
}In this example
MyModule
contains three methods to provide RestService, MyPrinter and MainService objects.
The DaggerMockRule rule dynamically creates a new module that override MyModule, it returns the mocks
for restService and myPrinter defined in the test instead of the real objects.
Espresso support
A DaggerMockRule can also be used in an Espresso test:
public class MainActivityTest {
@Rule public DaggerMockRule<MyComponent> daggerRule = new DaggerMockRule<>(MyComponent.class, new MyModule())
.set(new DaggerMockRule.ComponentSetter<MyComponent>() {
@Override public void setComponent(MyComponent component) {
App app = (App) InstrumentationRegistry.getInstrumentation().getTargetContext().getApplicationContext();
app.setComponent(component);
}
});
@Rule public ActivityTestRule<MainActivity> activityRule = new ActivityTestRule<>(MainActivity.class, false, false);
@Mock RestService restService;
@Mock MyPrinter myPrinter;
@Test
public void testCreateActivity() {
when(restService.doSomething()).thenReturn("abc");
activityRule.launchActivity(null);
verify(myPrinter).print("ABC");
}
}Robolectric support
In a similar way a DaggerMockRule can be used in a Robolectric test:
@RunWith(RobolectricGradleTestRunner.class)
@Config(constants = BuildConfig.class, sdk = 21)
public class MainActivityTest {
@Rule public final DaggerMockRule<MyComponent> mockitoRule = new DaggerMockRule<>(MyComponent.class, new MyModule())
.set(new DaggerMockRule.ComponentSetter<MyComponent>() {
@Override public void setComponent(MyComponent component) {
((App) RuntimeEnvironment.application).setComponent(component);
}
});
@Mock RestService restService;
@Mock MyPrinter myPrinter;
@Test
public void testCreateActivity() {
when(restService.doSomething()).thenReturn("abc");
Robolectric.setupActivity(MainActivity.class);
verify(myPrinter).print("ABC");
}
}Custom rules
It's easy to create a DaggerMockRule subclass to avoid copy and paste and simplify the test code:
public class MyRule extends DaggerMockRule<MyComponent> {
public MyRule() {
super(MyComponent.class, new MyModule());
set(new DaggerMockRule.ComponentSetter<MyComponent>() {
@Override public void setComponent(MyComponent component) {
App app = (App) InstrumentationRegistry.getInstrumentation().getTargetContext().getApplicationContext();
app.setComponent(component);
}
});
}
}The final test uses the rule subclass:
public class MainActivityTest {
@Rule public MyRule daggerRule = new MyRule();
@Rule public ActivityTestRule<MainActivity> activityRule = new ActivityTestRule<>(MainActivity.class, false, false);
@Mock RestService restService;
@Mock MyPrinter myPrinter;
@Test
public void testCreateActivity() {
when(restService.doSomething()).thenReturn("abc");
activityRule.launchActivity(null);
verify(myPrinter).print("ABC");
}
}JitPack configuration
DaggerMock is available on JitPack, add the JitPack repository in your build.gradle (in top level dir):
repositories {
jcenter()
maven { url "https://jitpack.io" }
}and the dependency in the build.gradle of the module:
dependencies {
compile 'com.github.fabioCollini:DaggerMock:0.4'
}License
Copyright 2016 Fabio Collini
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
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