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/*!
* Chai - addProperty utility
* Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
* MIT Licensed
*/
var chai = require('../../chai');
var flag = require('./flag');
var isProxyEnabled = require('./isProxyEnabled');
var transferFlags = require('./transferFlags');
/**
* ### .addProperty(ctx, name, getter)
*
* Adds a property to the prototype of an object.
*
* utils.addProperty(chai.Assertion.prototype, 'foo', function () {
* var obj = utils.flag(this, 'object');
* new chai.Assertion(obj).to.be.instanceof(Foo);
* });
*
* Can also be accessed directly from `chai.Assertion`.
*
* chai.Assertion.addProperty('foo', fn);
*
* Then can be used as any other assertion.
*
* expect(myFoo).to.be.foo;
*
* @param {Object} ctx object to which the property is added
* @param {String} name of property to add
* @param {Function} getter function to be used for name
* @namespace Utils
* @name addProperty
* @api public
*/
module.exports = function addProperty(ctx, name, getter) {
getter = getter === undefined ? function () {} : getter;
Object.defineProperty(ctx, name,
{ get: function propertyGetter() {
// Setting the `ssfi` flag to `propertyGetter` 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 and proxy protection is disabled.
//
// 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 proxy protection is enabled, then the `ssfi` flag has already been
// set by the proxy getter.
if (!isProxyEnabled() && !flag(this, 'lockSsfi')) {
flag(this, 'ssfi', propertyGetter);
}
var result = getter.call(this);
if (result !== undefined)
return result;
var newAssertion = new chai.Assertion();
transferFlags(this, newAssertion);
return newAssertion;
}
, configurable: true
});
};
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