javascript - 对角度教程步骤感到困惑

Question

来自https://docs.angularjs.org/tutorial/step_11单元测试部分：

it('should create "phones" model with 2 phones fetched from xhr', function() {
    expect(scope.phones).toEqualData([]);
    $httpBackend.flush();

    expect(scope.phones).toEqualData([{name: 'Nexus S'}, {name: 'Motorola DROID'}]);
});  

我只是不明白为什么第 2 行评估为真并且scope.phones正在[]追求

scope = $rootScope.$new();
ctrl = $controller(PhoneListCtrl, {$scope: scope});

beforectrl = $controller(PhoneListCtrl, {$scope: scope}); scope.phones评估为undefined和 after but before $httpBackend.flush()，它评估为一个空数组，有人可以解释一下这个谜吗？