lib/goog/labs/testing/matcher.js

1// Copyright 2012 The Closure Library Authors. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS-IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15/**
16 * @fileoverview Provides the base Matcher interface. User code should use the
17 * matchers through assertThat statements and not directly.
18 */
19
20
21goog.provide('goog.labs.testing.Matcher');
22
23
24
25/**
26 * A matcher object to be used in assertThat statements.
27 * @interface
28 */
29goog.labs.testing.Matcher = function() {};
30
31
32/**
33 * Determines whether a value matches the constraints of the match.
34 *
35 * @param {*} value The object to match.
36 * @return {boolean} Whether the input value matches this matcher.
37 */
38goog.labs.testing.Matcher.prototype.matches = function(value) {};
39
40
41/**
42 * Describes why the matcher failed.
43 *
44 * @param {*} value The value that didn't match.
45 * @param {string=} opt_description A partial description to which the reason
46 *     will be appended.
47 *
48 * @return {string} Description of why the matcher failed.
49 */
50goog.labs.testing.Matcher.prototype.describe =
51    function(value, opt_description) {};
52
53
54/**
55 * Generates a Matcher from the ‘matches’ and ‘describe’ functions passed in.
56 *
57 * @param {!Function} matchesFunction The ‘matches’ function.
58 * @param {Function=} opt_describeFunction The ‘describe’ function.
59 * @return {!Function} The custom matcher.
60 */
61goog.labs.testing.Matcher.makeMatcher =
62    function(matchesFunction, opt_describeFunction) {
63
64  /**
65   * @constructor
66   * @implements {goog.labs.testing.Matcher}
67   * @final
68   */
69  var matcherConstructor = function() {};
70
71  /** @override */
72  matcherConstructor.prototype.matches = matchesFunction;
73
74  if (opt_describeFunction) {
75    /** @override */
76    matcherConstructor.prototype.describe = opt_describeFunction;
77  }
78
79  return matcherConstructor;
80};