UiThreadStatement.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * 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.
 */

package androidx.test.internal.runner.junit4.statement;

import static androidx.test.InstrumentationRegistry.getInstrumentation;

import android.os.Looper;
import android.util.Log;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
import java.util.concurrent.atomic.AtomicReference;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.Statement;

/** {@link Statement} that executes a test on the application's main thread (or UI thread). */
public class UiThreadStatement extends Statement {
  private static final String TAG = "UiThreadStatement";

  private final Statement mBase;

  private final boolean mRunOnUiThread;

  public UiThreadStatement(Statement base, boolean runOnUiThread) {
    mBase = base;
    mRunOnUiThread = runOnUiThread;
  }

  public boolean isRunOnUiThread() {
    return mRunOnUiThread;
  }

  @Override
  public void evaluate() throws Throwable {
    if (mRunOnUiThread) {
      final AtomicReference<Throwable> exceptionRef = new AtomicReference<>();
      runOnUiThread(
          new Runnable() {
            @Override
            public void run() {
              try {
                mBase.evaluate();
              } catch (Throwable throwable) {
                exceptionRef.set(throwable);
              }
            }
          });
      Throwable throwable = exceptionRef.get();
      if (throwable != null) {
        throw throwable;
      }
    } else {
      mBase.evaluate();
    }
  }

  public static boolean shouldRunOnUiThread(FrameworkMethod method) {
    Class<android.test.UiThreadTest> deprecatedUiThreadTestClass = android.test.UiThreadTest.class;
    if (method.getAnnotation(deprecatedUiThreadTestClass) != null) {
      return true;
    } else {
      try {
        // to avoid circular dependency on Rules module use the class name directly
        @SuppressWarnings("unchecked") // reflection
        Class UiThreadTestClass = Class.forName("androidx.test.annotation.UiThreadTest");
        if (method.getAnnotation(deprecatedUiThreadTestClass) != null
            || method.getAnnotation(UiThreadTestClass) != null) {
          return true;
        }
      } catch (ClassNotFoundException e) {
        // ignore, annotation is not used.
      }
    }
    return false;
  }

  public static void runOnUiThread(final Runnable runnable) throws Throwable {
    if (Looper.myLooper() == Looper.getMainLooper()) {
      Log.w(
          TAG,
          "Already on the UI thread, this method should not be called from the "
              + "main application thread");
      runnable.run();
    } else {
      FutureTask<Void> task = new FutureTask<>(runnable, null);
      getInstrumentation().runOnMainSync(task);
      try {
        task.get();
      } catch (ExecutionException e) {
        // Expose the original exception
        throw e.getCause();
      }
    }
  }
}