Light cycle

Android library that helps you break BaseActivity and BaseFragment into smaller testable components.

Usage

public abstract class BaseActivity extends LightCycleActivity {
  @LightCycle ScreenStateProvider screenStateProvider;
  @LightCycle UserAccountController userAccountController;
  [...]
  
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
  }
}

class ScreenStateProvider extends DefaultLightCycleActivity<Activity> {
    private boolean isForeground;

    boolean isForeground() {
        return isForeground;
    }

    @Override
    public void onResume(Activity activity) {
        isForeground = true;
    }

    @Override
    public void onPause(Activity activity) {
        isForeground = false;
    }
}

Note : The LightCycle API is close to the ActivityLifecycleCallbacks API available since Android 14.

Principles

Collaborators over inheritance

Activities / Fragments are respeonsables for :

• Inflating layout and views
• Setting resources
• Hooking up lightcycles

Lightcycles are responsible for specific features, regarless the Activy or Fragment.

Testing the logic

A typical Light Cycle Activity or Fragment does not contain any logic and may not be tested.

A Light Cycle should not depend on any Android Framework specific classes, meaning it should not be needed to hook up resources or mock up views to test it.

public class ScreenStateProviderTest {
    @Mock private Activity activity;
    
    private ScreenStateProvider lightCycle;

    @Before
    public void setUp() throws Exception {
        lightCycle = new ScreenStateProvider();
    }

    @Test
    public void isNotForegroundByDefault() {
        expect(lightCycle.isForeground()).toBeFalse();
    }

    @Test
    public void isForegroundWhenOnResume() {
        lightCycle.onResume(activity);
        expect(lightCycle.isForeground()).toBeTrue();
    }

    @Test
    public void isNotForegroundOnPause() {
        lightCycle.onResume(activity);
        lightCycle.onPause(activity);
        expect(lightCycle.isForeground()).toBeFalse();
    }
[...]
}

Empower

LightCycles compose well with other injection libraries.

Exemple :

public abstract class BaseActivity extends LightCycleActivity {
  @Inject @Singleton @LightCycle ScreenStateProvider screenStateProvider;
  @Inject @LightCycle UserAccountController userAccountController;
  [...]
  
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
  }
}

Integration

Dependencies

Gradle :

compile com.soundcloud.lightcycle:lightcycle-processor:VERSION
compile com.soundcloud.lightcycle:lightcycle-lib:VERSION

Proguard

Add this to your config file.

-keep class com.soundcloud.lightcycle.** {
    *;
}