content: /*
   * 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.espresso;
  
  /**
   * Represents a resource of an application under test which can cause asynchronous background work
   * to happen during test execution (e.g. an intent service that processes a button click). By
   * default, {@link Espresso} synchronizes all view operations with the UI thread as well as
   * AsyncTasks; however, it has no way of doing so with "hand-made" resources. In such cases, test
   * authors can register the custom resource via {@link androidx.test.espresso.IdlingRegistry}
   * and {@link Espresso} will wait for the resource to become idle prior to executing a view
   * operation.
   *
   * <p><b>Important Note:</b> it is assumed that the resource stays idle most of the time.
   *
   * <p><b>Note:</b> before writing your implementation consider using
   * {@link androidx.test.espresso.idling.CountingIdlingResource} instead.
   */
  public interface IdlingResource {
  
    /** Returns the name of the resources (used for logging and idempotency of registration). */
    public String getName();
  
    /**
     * Returns {@code true} if resource is currently idle. Espresso will <b>always</b> call this
     * method from the main thread, therefore it should be non-blocking and return immediately.
     */
    public boolean isIdleNow();
  
    /**
     * Registers the given {@link ResourceCallback} with the resource. Espresso will call this method:
     *
     * <ul>
     *   <li>with its implementation of {@link ResourceCallback} so it can be notified asynchronously
     *       that your resource is idle
     *   <li>from the main thread, but you are free to execute the callback's onTransitionToIdle from
     *       any thread
     *   <li>once (when it is initially given a reference to your IdlingResource)
     * </ul>
     *
     * <p>You only need to call this upon transition from busy to idle - if the resource is already
     * idle when the method is called invoking the call back is optional and has no significant
     * impact.
     */
    public void registerIdleTransitionCallback(ResourceCallback callback);
  
    /** Registered by an {@link IdlingResource} to notify Espresso of a transition to idle. */
    public interface ResourceCallback {
      /** Called when the resource goes from busy to idle. */
      public void onTransitionToIdle();
    }
  }
  