[英]How to mock a Scala singleton object?
我试图模拟Scala单例对象。 特别是,我需要模拟服务组件(测试中的类)中使用的对象play.api.libs.ws.WS
使用Mockito这是不可能的,测试执行失败的方式如下:
[error] MockitoException: :
[error] Cannot mock/spy class play.api.libs.ws.WS$
[error] Mockito cannot mock/spy following:
[error] - final classes
[error] - anonymous classes
[error] - primitive types (GeolocationSpec.scala:18)
在这里阅读,似乎Scalamock允许这样做:
要模拟独立的单例对象,请使用
org.scalamock.annotation.mockObject
。
我的服务组件是这样的:
trait GeolocationService {
def wsClient = WS
def getPath(origin: Location, destination: Location): Future[Route]
}
class DefaultGeolocationService extends GeolocationService {
val serviceProviderEndpoint = Play.current.configuration.getString("api.directions.endpoint")
override def getPath(origin: Location, destination: Location): Future[Route] = {
val params = Seq(
"origin" -> s"${origin.lat},${origin.lon}",
"destination" -> s"${destination.lat},${destination.lon}"
);
val resp = wsClient.url(serviceProviderEndpoint.get).withQueryString(params: _*).get()
resp.map {
// omitted code
}
}
}
我的build.sbt具有所有这些依赖项:
[...]
"org.scalatest" %% "scalatest" % "2.2.1",
"org.specs2" %% "specs2" % "2.3.13" % "test",
"org.scalamock" %% "scalamock-specs2-support" % "3.0.1" % "test",
"org.scalamock" %% "scalamock-scalatest-support" % "3.0.1" % "test",
"org.scalamock" %% "scalamock" % "3.0.1",
[...]
但我找不到这个: org.scalamock.annotation.mockObject
也许这也可以使用EasyMock和PowerMock完成,但我找不到任何Scala示例代码。
任何的想法?
使用ScalaMock 3模拟单例对象是不可能的 ,但Paul Butcher希望在ScalaMock 4中重新引入此功能(请参阅http://paulbutcher.com/2014/04/15/scalamock-status-report/ )
不要嘲笑单身人士。 而不是WS,使您的服务组件依赖于隐藏它的瘦外观:
trait GeolocationService {
def ws: (String, Seq[String]) => Promise[Response] = { (url, params) =>
wsClient.url(serviceProviderEndpoint.get).withQueryString(params: _*).get()
}
def getPath(origin: Location, destination: Location): Future[Route]
}
在你的测试中,只需使用mock重写ws方法,现在很容易创建:
val mockedWs = mock[(String, Seq[String]) => Promise[Response]]
// TODO specify mock's behavior here
val service = new DefaultGeolocationService() {
override def ws = mockedWs
}
为什么你不使用蛋糕模式?
它有点冗长但它会解决你的嘲弄问题。
trait GeolocationServiceComponent {
val geolocationService:GeolocationService
trait GeolocationService {
def wsClient
def getPath(origin:Location, destination: Location): Future[Route]
}
}
trait GeolocationServiceComponentImpl {
val geolocationService = new GeolocationService {
override def wsClient = WS
}
}
class DefaultGeolocationService extends GeolocationServiceComponent ...
//Defined into your test class
trait MockGeolocationServiceComponent {
val geolocationService = Mock[GeolocationService]
//Here you define your mock logic
}
您也可以使用monads来执行此操作,但我从未实现过,这里描述: Scala依赖注入:隐式参数的替代方法
我不喜欢改变设计以适应这种限制。 基本上我能得到的就是改变设计,然后使用模拟框架
//since mocking frameworks on SCALA is not support mocking singleton
//hacks are either required to change the design or ...
//I'd rather putting the mocking logic here by myself
var testUser:Option[User] = None;
def getCurrentUser(request: Request[Object]) = {
if( testUser != None ){
testUser;
}
希望能帮助到你。
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