使用茉莉來窺探document.createElement從角度模擬中拋出錯誤

我有一個處理網絡攝像機的Angular服務。下面是我想要測試功能：使用茉莉來窺探document.createElement從角度模擬中拋出錯誤

this.takePicture = function() { 
    var canvas = document.createElement('canvas'); 
    canvas.width = this.width; 
    canvas.height = this.height; 

    var context = canvas.getContext('2d'); 
    context.drawImage(this.videoElement, 0, 0, this.width, this.height); 

    return canvas.toDataURL('image/jpeg', 100); 
};

我試圖嘲弄調用使用document.createElement並返回一個假的畫布對象。下面是我的測試：

it('should draw an image', function() { 
    var drawImageSpy = jasmine.createSpy('drawImage'); 

    var canvas = { 
     getContext: jasmine.createSpy('getContext').and.returnValue({ drawImage: drawImageSpy }), 
     width: 0, 
     height: 0, 
     toDataURL: jasmine.createSpy('toDataUrl').and.returnValue('data-uri') 
    }; 

    document.createElement = jasmine.createSpy('createCanvas').and.returnValue(canvas); 

    WcCameraService.takePicture(); 

    expect(drawImageSpy).toHaveBeenCalled(); 
});

這是我得到的錯誤：

TypeError: Failed to execute 'appendChild' on 'Node': parameter 1 is not of type 'Node'. 
    at TypeError (native) 
    at Function.jQuery.extend.buildFragment (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/jquery/dist/jquery.js:5565:24) 
    at Function.jQuery.parseHTML (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/jquery/dist/jquery.js:9923:18) 
    at jQuery.fn.init (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/jquery/dist/jquery.js:2774:33) 
    at Object.jQuery [as element] (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/jquery/dist/jquery.js:73:10) 
    at $get (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/angular-mocks/angular-mocks.min.js:6:18224) 
    at Object.e [as invoke] (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/angular/angular.min.js:39:193) 
    at C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/angular/angular.min.js:41:10 
    at Object.d [as get] (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/angular/angular.min.js:38:394) 
    at Object.<anonymous> (C:/Projects/Accurev/WebCOE_FRF_DEV/src/bower_components/angular-mocks/angular-mocks.min.js:6:21105)

任何人都不會有爲什麼發生這種情況的任何想法？我正在尋找角模擬，它似乎在這一點上失敗：

if (window.jasmine || window.mocha) { 

... 

    if (injector) { 
    injector.get('$rootElement').off(); 
    }

來源

2016-02-12 Shane Brunson

據我所知，document.createElement是不可變的。你真的不應該在第一時間監視它。這是一種每次都會以相同方式執行的內置函數。你的其他間諜看起來很好。

來源

2016-02-12 22:31:46 MBielski

使用茉莉來窺探document.createElement從角度模擬中拋出錯誤

回答

相關問題