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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
const EXPORTED_SYMBOLS = ["MockObjectReplacer", "MockObjectRegisterer"];
var Cm = Components.manager;
function MockObjectRegisterer(aContractID, aCID, aComponent) {
this._contractID = aContractID;
this._cid = Components.ID("{" + aCID + "}");
this._component = aComponent;
}
MockObjectRegisterer.prototype = {
register() {
let providedConstructor = this._component;
this._mockFactory = {
createInstance(aIid) {
return new providedConstructor().QueryInterface(aIid);
},
};
let componentRegistrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
componentRegistrar.registerFactory(
this._cid,
"",
this._contractID,
this._mockFactory
);
},
unregister() {
let componentRegistrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
componentRegistrar.unregisterFactory(this._cid, this._mockFactory);
},
};
/**
* 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
* Ci.nsIFilePicker).
*/
function MockObjectReplacer(aContractID, aReplacementCtor) {
this._contractID = aContractID;
this._replacementCtor = aReplacementCtor;
this._cid = null;
}
MockObjectReplacer.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() {
if (this._cid) {
throw Error("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(aIid) {
return new providedConstructor().QueryInterface(aIid);
},
};
var retVal = swapFactoryRegistration(
this._cid,
this._originalCID,
this._contractID,
this._mockFactory
);
if ("error" in retVal) {
throw new Error("ERROR: " + retVal.error);
} else {
this._cid = retVal.cid;
this._originalCID = retVal.originalCID;
}
},
/**
* Restores the original factory.
*/
unregister() {
if (!this._cid) {
throw Error("Invalid object state when calling unregister()");
}
// Free references to the mock factory.
swapFactoryRegistration(
this._cid,
this._originalCID,
this._contractID,
this._mockFactory
);
// Allow registering a mock factory again later.
this._cid = null;
this._originalCID = null;
this._mockFactory = null;
},
// --- Private methods and properties ---
/**
* The CID under which the mock contractID was registered.
*/
_cid: null,
/**
* The nsIFactory that was automatically generated by this object.
*/
_mockFactory: null,
};
/**
* Swiped from mozilla/testing/mochitest/tests/SimpleTest/specialpowersAPI.js
*/
function swapFactoryRegistration(CID, originalCID, contractID, newFactory) {
let componentRegistrar = Cm.QueryInterface(Ci.nsIComponentRegistrar);
if (originalCID == null) {
if (contractID != null) {
originalCID = componentRegistrar.contractIDToCID(contractID);
void Cm.getClassObject(Cc[contractID], Ci.nsIFactory);
} else {
return {
error: "trying to register a new contract ID: Missing contractID",
};
}
CID = Services.uuid.generateUUID();
componentRegistrar.registerFactory(CID, "", contractID, newFactory);
} else {
componentRegistrar.unregisterFactory(CID, newFactory);
// Restore the original factory.
componentRegistrar.registerFactory(originalCID, "", contractID, null);
}
return { cid: CID, originalCID };
}
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