// Copyright 2012 The Closure Library Authors. All Rights Reserved.
//
// 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.

/**
 * @fileoverview Provides the base Matcher interface. User code should use the
 * matchers through assertThat statements and not directly.
 */


goog.provide('goog.labs.testing.Matcher');



/**
 * A matcher object to be used in assertThat statements.
 * @interface
 */
goog.labs.testing.Matcher = function() {};


/**
 * Determines whether a value matches the constraints of the match.
 *
 * @param {*} value The object to match.
 * @return {boolean} Whether the input value matches this matcher.
 */
goog.labs.testing.Matcher.prototype.matches = function(value) {};


/**
 * Describes why the matcher failed.
 *
 * @param {*} value The value that didn't match.
 * @param {string=} opt_description A partial description to which the reason
 *     will be appended.
 *
 * @return {string} Description of why the matcher failed.
 */
goog.labs.testing.Matcher.prototype.describe = function(
    value, opt_description) {};


/**
 * Generates a Matcher from the ‘matches’ and ‘describe’ functions passed in.
 *
 * @param {!Function} matchesFunction The ‘matches’ function.
 * @param {Function=} opt_describeFunction The ‘describe’ function.
 * @return {!Function} The custom matcher.
 */
goog.labs.testing.Matcher.makeMatcher = function(
    matchesFunction, opt_describeFunction) {

  /**
   * @constructor
   * @implements {goog.labs.testing.Matcher}
   * @final
   */
  var matcherConstructor = function() {};

  /** @override */
  matcherConstructor.prototype.matches = matchesFunction;

  if (opt_describeFunction) {
    /** @override */
    matcherConstructor.prototype.describe = opt_describeFunction;
  }

  return matcherConstructor;
};
