问题是文档仅描述代码的“成功/快乐”分支，并且没有如何测试“失败”分支的示例。

我想做的是设置触发$ scope.status =’ERROR！’的前提条件码。

这是一个最小的例子。

// controller
function MyController($scope,$http) {

  this.saveMessage = function(message) {
    $scope.status = 'Saving...';
    $http.post('/add-msg.py',message).success(function(response) {
      $scope.status = '';
    }).error(function() {
      $scope.status = 'ERROR!';
    });
  };
}

// testing controller
var $httpBackend;

beforeEach(inject(function($injector) {
  $httpBackend = $injector.get('$httpBackend');
}));

it('should send msg to server',function() {

  $httpBackend.expectPOST('/add-msg.py','message content').respond(500,'');

  var controller = scope.$new(MyController);
  $httpBackend.flush();
  controller.saveMessage('message content');
  $httpBackend.flush();

  // Here is the question: How to set $httpBackend.expectPOST to trigger
  // this condition.
  expect(scope.status).toBe('ERROR!');
});

});