如何模拟Scala单例对象? [英] How to mock a Scala singleton object?

问题描述

我正在尝试模拟Scala单例对象.特别是，我需要模拟在服务组件(被测类)中使用的对象play.api.libs.ws.WS. 使用Mockito是不可能的，测试执行将通过以下方式失败:

I am trying to mock a Scala singleton object. In particular, I need to mock the object play.api.libs.ws.WS used inside a service component (class under test). Using Mockito this is not possible, the test execution fails in the following way:

[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)

在此处中阅读，看来Scalamock允许这样做:

Reading here, it seems that Scalamock allows to do it:

要模拟独立的单例对象，请使用 org.scalamock.annotation.mockObject.

To mock a standalone singleton object, use org.scalamock.annotation.mockObject.

我的服务组件是这样的:

My service component is something like this:

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:

My build.sbt has all these dependencies:

[...]
"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",
[...]

但是我找不到这个:org.scalamock.annotation.mockObject

可能也可以使用EasyMock和PowerMock来完成，但是我找不到任何Scala示例代码.

Probably this can be done also using EasyMock and PowerMock, but I cannot find any Scala example code.

有什么主意吗?

推荐答案

使用ScalaMock 3模拟单例对象是不可能的 ，但是Paul Butcher希望在ScalaMock 4中重新引入此功能(请参见 http://paulbutcher.com/2014/04/15/scalamock-status-report/)

Mocking singleton objects using ScalaMock 3 is not possible, however Paul Butcher expects to reintroduce this feature in ScalaMock 4 (see http://paulbutcher.com/2014/04/15/scalamock-status-report/)

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