Added tests to assert when LifecycleObserver is implemented.

Author: mvanbeusekom

packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/CameraTest.java

@@ -5,6 +5,7 @@
 package io.flutter.plugins.camera;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
@@ -27,6 +28,7 @@
 import android.os.Handler;
 import android.os.HandlerThread;
 import androidx.annotation.NonNull;
+import androidx.lifecycle.LifecycleObserver;
 import io.flutter.embedding.engine.systemchannels.PlatformChannel;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugins.camera.features.CameraFeatureFactory;
@@ -112,6 +114,13 @@ public void after() {
     mockHandlerFactory.close();
   }
 
+  @Test
+  public void shouldNotImplementLifecycleObserverInterface() {
+    Class<Camera> cameraClass = Camera.class;
+
+    assertFalse(LifecycleObserver.class.isAssignableFrom(cameraClass));
+  }
+
   @Test
   public void shouldCreateCameraPluginAndSetAllFeatures() {
     final Activity mockActivity = mock(Activity.class);

packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/MethodCallHandlerImplTest.java

@@ -4,13 +4,15 @@
 
 package io.flutter.plugins.camera;
 
+import static org.junit.Assert.assertFalse;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 
 import android.app.Activity;
 import android.hardware.camera2.CameraAccessException;
+import androidx.lifecycle.LifecycleObserver;
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
@@ -39,6 +41,13 @@ public void setUp() {
     TestUtils.setPrivateField(handler, "camera", mockCamera);
   }
 
+  @Test
+  public void shouldNotImplementLifecycleObserverInterface() {
+    Class<MethodCallHandlerImpl> methodCallHandlerClass = MethodCallHandlerImpl.class;
+
+    assertFalse(LifecycleObserver.class.isAssignableFrom(methodCallHandlerClass));
+  }
+
   @Test
   public void onMethodCall_pausePreview_shouldPausePreviewAndSendSuccessResult()
       throws CameraAccessException {