| /*! |
| * Chai - overwriteMethod utility |
| * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com> |
| * MIT Licensed |
| */ |
| |
| var addLengthGuard = require('./addLengthGuard'); |
| var chai = require('../../chai'); |
| var flag = require('./flag'); |
| var proxify = require('./proxify'); |
| var transferFlags = require('./transferFlags'); |
| |
| /** |
| * ### .overwriteMethod(ctx, name, fn) |
| * |
| * Overwrites an already existing method and provides |
| * access to previous function. Must return function |
| * to be used for name. |
| * |
| * utils.overwriteMethod(chai.Assertion.prototype, 'equal', function (_super) { |
| * return function (str) { |
| * var obj = utils.flag(this, 'object'); |
| * if (obj instanceof Foo) { |
| * new chai.Assertion(obj.value).to.equal(str); |
| * } else { |
| * _super.apply(this, arguments); |
| * } |
| * } |
| * }); |
| * |
| * Can also be accessed directly from `chai.Assertion`. |
| * |
| * chai.Assertion.overwriteMethod('foo', fn); |
| * |
| * Then can be used as any other assertion. |
| * |
| * expect(myFoo).to.equal('bar'); |
| * |
| * @param {Object} ctx object whose method is to be overwritten |
| * @param {String} name of method to overwrite |
| * @param {Function} method function that returns a function to be used for name |
| * @namespace Utils |
| * @name overwriteMethod |
| * @api public |
| */ |
| |
| module.exports = function overwriteMethod(ctx, name, method) { |
| var _method = ctx[name] |
| , _super = function () { |
| throw new Error(name + ' is not a function'); |
| }; |
| |
| if (_method && 'function' === typeof _method) |
| _super = _method; |
| |
| var overwritingMethodWrapper = function () { |
| // Setting the `ssfi` flag to `overwritingMethodWrapper` causes this |
| // function to be the starting point for removing implementation frames from |
| // the stack trace of a failed assertion. |
| // |
| // However, we only want to use this function as the starting point if the |
| // `lockSsfi` flag isn't set. |
| // |
| // If the `lockSsfi` flag is set, then either this assertion has been |
| // overwritten by another assertion, or this assertion is being invoked from |
| // inside of another assertion. In the first case, the `ssfi` flag has |
| // already been set by the overwriting assertion. In the second case, the |
| // `ssfi` flag has already been set by the outer assertion. |
| if (!flag(this, 'lockSsfi')) { |
| flag(this, 'ssfi', overwritingMethodWrapper); |
| } |
| |
| // Setting the `lockSsfi` flag to `true` prevents the overwritten assertion |
| // from changing the `ssfi` flag. By this point, the `ssfi` flag is already |
| // set to the correct starting point for this assertion. |
| var origLockSsfi = flag(this, 'lockSsfi'); |
| flag(this, 'lockSsfi', true); |
| var result = method(_super).apply(this, arguments); |
| flag(this, 'lockSsfi', origLockSsfi); |
| |
| if (result !== undefined) { |
| return result; |
| } |
| |
| var newAssertion = new chai.Assertion(); |
| transferFlags(this, newAssertion); |
| return newAssertion; |
| } |
| |
| addLengthGuard(overwritingMethodWrapper, name, false); |
| ctx[name] = proxify(overwritingMethodWrapper, name); |
| }; |