单元测试AngularJS指令,该指令监视具有隔离范围的属性

Question

我有一个指令,它使用隔离范围将数据传递给随时间变化的指令.它会监视该值的变化,并对每次更改进行一些计算.当我尝试对指令进行单元测试时,我无法触发手表(为简洁而修剪,但基本概念如下所示):

指示:

angular.module('directives.file', [])
.directive('file', function() {
  return {
    restrict: 'E',
    scope: {
      data: '=',
      filename: '@',
    },
    link: function(scope, element, attrs) {
      console.log('in link');
      var convertToCSV = function(newItem) { ... };

      scope.$watch('data', function(newItem) {
        console.log('in watch');
        var csv_obj = convertToCSV(newItem);
        var blob = new Blob([csv_obj], {type:'text/plain'});
        var link = window.webkitURL.createObjectURL(blob);
        element.html('<a href=' + link + ' download=' + attrs.filename +'>Export to CSV</a>');
      }, true);
    }
  };
});

测试:

describe('Unit: File export', function() {
  var scope;

  beforeEach(module('directives.file'));
  beforeEach(inject(function ($rootScope, $compile) {
    scope = $rootScope.$new();
  };

  it('should create a CSV', function() {
    scope.input = someData;
    var e = $compile('<file data="input" filename="filename.csv"></file>')(scope);
    //I've also tried below but that does not help
    scope.$apply(function() { scope.input = {}; });
  });

我该怎么做才能触发手表,以便触发我的"In watch"调试语句？我编译时会触发"链接".

Answer 1

对于$watch得到触发,必须在它被定义的范围或其父发生消化周期.由于您的指令创建了隔离范围,因此它不会从父范围继承,因此在您调用$apply适当的范围之前,它的观察者不会被处理.

您可以通过调用服务scope()返回的元素来访问指令范围$compile:

scope.input = someData;
var e = $compile('<file data="input" filename="filename.csv"></file>')(scope);
e.isolateScope().$apply();

这个jsFiddler举例说明了这一点.