/*
 * Copyright (C) 2013 DroidDriver committers
 *
 * 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 io.appium.droiddriver.validators;

import io.appium.droiddriver.UiElement;
import io.appium.droiddriver.actions.Action;

/**
 * Interface for validating a UiElement, checked when an action is performed.
 * For example, in general accessibility mandates that an actionable UiElement
 * has content description or text.
 */
public interface Validator {
  /**
   * Returns true if this {@link Validator} applies to {@code element} on this
   * {@code action}.
   */
  boolean isApplicable(UiElement element, Action action);

  /**
   * Returns {@code null} if {@code element} is valid on this {@code action},
   * otherwise a string describing the failure.
   */
  String validate(UiElement element, Action action);
}