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1 /* This Source Code Form is subject to the terms of the Mozilla Public |
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2 * License, v. 2.0. If a copy of the MPL was not distributed with this |
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3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
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4 |
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5 /** |
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6 * Allows registering a mock XPCOM component, that temporarily replaces the |
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7 * original one when an object implementing a given ContractID is requested |
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8 * using createInstance. |
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9 * |
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10 * @param aContractID |
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11 * The ContractID of the component to replace, for example |
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12 * "@mozilla.org/filepicker;1". |
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13 * |
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14 * @param aReplacementCtor |
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15 * The constructor function for the JavaScript object that will be |
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16 * created every time createInstance is called. This object must |
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17 * implement QueryInterface and provide the XPCOM interfaces required by |
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18 * the specified ContractID (for example |
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19 * Components.interfaces.nsIFilePicker). |
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20 */ |
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21 |
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22 function MockObjectRegisterer(aContractID, aReplacementCtor) { |
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23 this._contractID = aContractID; |
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24 this._replacementCtor = aReplacementCtor; |
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25 } |
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26 |
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27 MockObjectRegisterer.prototype = { |
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28 /** |
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29 * Replaces the current factory with one that returns a new mock object. |
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30 * |
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31 * After register() has been called, it is mandatory to call unregister() to |
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32 * restore the original component. Usually, you should use a try-catch block |
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33 * to ensure that unregister() is called. |
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34 */ |
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35 register: function MOR_register() { |
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36 if (this._originalFactory) |
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37 throw new Exception("Invalid object state when calling register()"); |
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38 |
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39 // Define a factory that creates a new object using the given constructor. |
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40 var providedConstructor = this._replacementCtor; |
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41 this._mockFactory = { |
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42 createInstance: function MF_createInstance(aOuter, aIid) { |
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43 if (aOuter != null) |
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44 throw SpecialPowers.Cr.NS_ERROR_NO_AGGREGATION; |
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45 return new providedConstructor().QueryInterface(aIid); |
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46 } |
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47 }; |
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48 |
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49 var retVal = SpecialPowers.swapFactoryRegistration(this._cid, this._contractID, this._mockFactory, this._originalFactory); |
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50 if ('error' in retVal) { |
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51 throw new Exception("ERROR: " + retVal.error); |
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52 } else { |
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53 this._cid = retVal.cid; |
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54 this._originalFactory = retVal.originalFactory; |
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55 } |
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56 }, |
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57 |
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58 /** |
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59 * Restores the original factory. |
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60 */ |
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61 unregister: function MOR_unregister() { |
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62 if (!this._originalFactory) |
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63 throw new Exception("Invalid object state when calling unregister()"); |
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64 |
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65 // Free references to the mock factory. |
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66 SpecialPowers.swapFactoryRegistration(this._cid, this._contractID, this._mockFactory, this._originalFactory); |
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67 |
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68 // Allow registering a mock factory again later. |
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69 this._cid = null; |
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70 this._originalFactory = null; |
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71 this._mockFactory = null; |
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72 }, |
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73 |
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74 // --- Private methods and properties --- |
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75 |
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76 /** |
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77 * The factory of the component being replaced. |
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78 */ |
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79 _originalFactory: null, |
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80 |
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81 /** |
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82 * The CID under which the mock contractID was registered. |
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83 */ |
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84 _cid: null, |
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85 |
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86 /** |
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87 * The nsIFactory that was automatically generated by this object. |
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88 */ |
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89 _mockFactory: null |
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90 } |