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;
  
  import android.view.View;
  
  /**
   * Responsible for performing assertions on a View element.<br>
   *
   * <p>This is considered part of the test framework public API - developers are free to write their
   * own assertions as long as they meet the following requirements:
   *
   * <ul>
   *   <li>Do not mutate the passed in view.
   *   <li>Throw junit.framework.AssertionError when the view assertion does not hold.
   *   <li>Implementation runs on the UI thread - so it should not do any blocking operations
   *   <li>Downcasting the view to a specific type is allowed, provided there is a test that view is
   *       an instance of that type before downcasting. If not, an AssertionError should be thrown.
   *   <li>It is encouraged to access non-mutating methods on the view to perform assertion.
   * </ul>
   *
   * <br>
   *
   * <p>Strongly consider using a existing ViewAssertion via the ViewAssertions utility class before
   * writing your own assertion.
   */
  public interface ViewAssertion {
  
    /**
     * Checks the state of the given view (if such a view is present).
     *
     * @param view the view, if one was found during the view interaction or null if it was not (which
     *     may be an acceptable option for an assertion)
     * @param noViewFoundException an exception detailing why the view could not be found or null if
     *     the view was found
     */
    void check(View view, NoMatchingViewException noViewFoundException);
  }
  