gecko/toolkit/content/tests/browser/common/mockObjects.js

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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla XUL Toolkit Testing Code.
*
* The Initial Developer of the Original Code is
* Paolo Amadini <http://www.amadzone.org/>.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/**
* Allows registering a mock XPCOM component, that temporarily replaces the
* original one when an object implementing a given ContractID is requested
* using createInstance.
*
* @param aContractID
* The ContractID of the component to replace, for example
* "@mozilla.org/filepicker;1".
*
* @param aReplacementCtor
* The constructor function for the JavaScript object that will be
* created every time createInstance is called. This object must
* implement QueryInterface and provide the XPCOM interfaces required by
* the specified ContractID (for example
* Components.interfaces.nsIFilePicker).
*/
function MockObjectRegisterer(aContractID, aReplacementCtor)
{
this._contractID = aContractID;
this._replacementCtor = aReplacementCtor;
}
MockObjectRegisterer.prototype = {
/**
* Replaces the current factory with one that returns a new mock object.
*
* After register() has been called, it is mandatory to call unregister() to
* restore the original component. Usually, you should use a try-catch block
* to ensure that unregister() is called.
*/
register: function MOR_register() {
if (this._originalFactory)
throw new Exception("Invalid object state when calling register()");
// Define a factory that creates a new object using the given constructor.
var providedConstructor = this._replacementCtor;
this._mockFactory = {
createInstance: function MF_createInstance(aOuter, aIid) {
if (aOuter != null)
throw Cr.NS_ERROR_NO_AGGREGATION;
return new providedConstructor().QueryInterface(aIid);
}
};
// Preserve the original factory.
this._originalFactory = Cm.getClassObjectByContractID(this._contractID,
Ci.nsIFactory);
// Replace the original factory with the mock one.
var classInfo = this._originalFactory.QueryInterface(Ci.nsIClassInfo);
var componentRegistrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
componentRegistrar.registerFactory(classInfo.classID,
"Mock " + classInfo.classDescription,
this._contractID,
this._mockFactory);
},
/**
* Restores the original factory.
*/
unregister: function MOR_unregister() {
if (!this._originalFactory)
throw new Exception("Invalid object state when calling unregister()");
// Free references to the mock factory.
var classInfo = this._originalFactory.QueryInterface(Ci.nsIClassInfo);
var componentRegistrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
componentRegistrar.unregisterFactory(classInfo.classID,
this._mockFactory);
// Restore the original factory.
componentRegistrar.registerFactory(classInfo.classID,
classInfo.classDescription,
this._contractID,
this._originalFactory);
// Allow registering a mock factory again later.
this._originalFactory = null;
this._mockFactory = null;
},
// --- Private methods and properties ---
/**
* The original nsIFactory for the component being replaced, or null when the
* original component is in place.
*/
_originalFactory: null,
/**
* The nsIFactory that was automatically generated by this object.
*/
_mockFactory: null
}