Provider mock error: Expected a spy, but got Function - angularjs

Question

I'm very new to jasmine and I got some issue trying to mock a provider.
I have a provider that looks like :
angular.module('myApp')
.factory('MyService', function ($resource) {
return {
actionResource : function(projectId, actionId){
var url = 'blablabla';
if(actionId){
url += "/"+actionId;
}
return $resource(url, {}, {
'create': {
method: 'POST'
}
});
},
};
});
I have a controller using this factory
angular.module('myApp')
.controller('myCtrl', function ($scope, MyService, $state) {
$scope.addAction = function(){
MyService.actionResource($scope.projectId).create($scope.action,
function(){
$state.go('somewhere', {});
});
};
});
and I'd really like to test this controller, at the moment I'm doing something like :
'use strict';
describe('[test] [controller] - myCtrl', function() {
beforeEach(angular.mock.module('myApp'));
//mock creation
beforeEach(
module(function($provide) {
$provide.factory('MyService', function() {
var actionResource = function(projectId, actionId){
var create = function(){return {}};
return {create:create};
}
return {actionResource:actionResource}
}
)})
);
var $httpBackend, $rootScope, myController, mockMyService;
var scope = {};
beforeEach(angular.mock.inject(function($injector, $rootScope, MyService) {
var $controller = $injector.get('$controller');
scope=$rootScope.$new();
mockMyService = MyService;
spyOn(mockPilotageService, 'actionResource').and.callThrough();
spyOn(mockPilotageService.actionResource(), 'create');
createController = function() {
return $controller("myCtrl", {$scope:scope, myService:mockMyService});
};
}));
it('myCtrl - addAction() calls actionRessource.create() method', function() {
createController();
scope.addAction();
expect(mockMyService).toBeDefined();
expect(mockMyService.actionResource).toHaveBeenCalled();
expect(mockMyService.actionResource().create).toHaveBeenCalled();
});
});
and I'm getting this error :
Error: Expected a spy, but got Function.
at /Users/*****/myController.spec.js:86
So it's able to spy on mockMyService.actionResource but not on mockMyService.actionResource().create. I can't understand why
any help would be more than welcome
thanks