RenderingComponentTest.java

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package io.flutter.embedding.engine;
 
import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
 
import androidx.test.ext.junit.runners.AndroidJUnit4;
import io.flutter.embedding.engine.renderer.FlutterRenderer;
import io.flutter.embedding.engine.renderer.FlutterUiDisplayListener;
import java.util.concurrent.atomic.AtomicInteger;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.annotation.Config;
 
@Config(manifest = Config.NONE)
@RunWith(AndroidJUnit4.class)
public class RenderingComponentTest {
  @Test
  public void flutterUiDisplayListenersCanRemoveThemselvesWhenInvoked() {
    // Setup test.
    FlutterJNI flutterJNI = new FlutterJNI();
    FlutterRenderer flutterRenderer = new FlutterRenderer(flutterJNI);
 
    AtomicInteger listenerInvocationCount = new AtomicInteger(0);
    FlutterUiDisplayListener listener =
        new FlutterUiDisplayListener() {
          @Override
          public void onFlutterUiDisplayed() {
            // This is the behavior we're testing, but we also verify that this method
            // was invoked to ensure that this test behavior executed.
            flutterRenderer.removeIsDisplayingFlutterUiListener(this);
 
            // Track the invocation to ensure this method is called once, and only once.
            listenerInvocationCount.incrementAndGet();
          }
 
          @Override
          public void onFlutterUiNoLongerDisplayed() {}
        };
    flutterRenderer.addIsDisplayingFlutterUiListener(listener);
 
    // Execute behavior under test.
    // Pretend we are the native side and tell FlutterJNI that Flutter has rendered a frame.
    flutterJNI.onFirstFrame();
 
    // Verify results.
    // If we got to this point without an exception, and if our listener was called one time,
    // then the behavior under test is correct.
    assertEquals(1, listenerInvocationCount.get());
  }
 
  @Test
  public void flutterUiDisplayListenersAddedAfterFirstFrameAreAutomaticallyInvoked() {
    // Setup test.
    FlutterJNI flutterJNI = new FlutterJNI();
    FlutterRenderer flutterRenderer = new FlutterRenderer(flutterJNI);
 
    FlutterUiDisplayListener listener = mock(FlutterUiDisplayListener.class);
 
    // Pretend we are the native side and tell FlutterJNI that Flutter has rendered a frame.
    flutterJNI.onFirstFrame();
 
    // Execute behavior under test.
    flutterRenderer.addIsDisplayingFlutterUiListener(listener);
 
    // Verify results.
    verify(listener, times(1)).onFlutterUiDisplayed();
  }
 
  @Test
  public void flutterUiDisplayListenersAddedAfterFlutterUiDisappearsAreNotInvoked() {
    // Setup test.
    FlutterJNI flutterJNI = new FlutterJNI();
    FlutterRenderer flutterRenderer = new FlutterRenderer(flutterJNI);
 
    FlutterUiDisplayListener listener = mock(FlutterUiDisplayListener.class);
 
    // Pretend we are the native side and tell FlutterJNI that Flutter has rendered a frame.
    flutterJNI.onFirstFrame();
 
    // Pretend that rendering has stopped.
    flutterJNI.onRenderingStopped();
 
    // Execute behavior under test.
    flutterRenderer.addIsDisplayingFlutterUiListener(listener);
 
    // Verify results.
    verify(listener, never()).onFlutterUiDisplayed();
  }
}