ScalaMock.模拟一个带有参数的类 [英] ScalaMock. Mock a class that takes arguments

问题描述

全面披露:我对模拟和模拟框架还是很陌生的.我正在尝试使用ScalaMock，因为它看起来像与ScalaTest一起使用的默认"模拟框架，但我很乐意使用与ScalaTest兼容的任何其他框架.

问题:我已经在Scala中编写了一个与套接字对话的类.该类具有要与之通信的套接字类型的类型参数，并且其参数之一是用于创建该类型套接字的工厂.它具有签名:

class XScanner[T <: SocketClient](
  confPath: String = "/etc/default/configPath",
  socketClientFactory: String => T
) extends ScannerBase(path)

我希望能够通过提供一个模拟SocketClient来为此类编写单元测试，这样我的测试代码不必连接到真正的套接字，但是我无法弄清楚如何使用ScalaMock做到这一点. /p>

我的测试代码如下:

val t = new XScanner[SocketClient](confPath, (s: String) => mock[SocketClient])

显然不会编译，因为SocketClient希望将套接字的路径作为参数，但是我不能调用mock[SocketClient(s)]，因为那不是类型，我也不能调用mock[SocketClient](s)，因为模拟没有接受传递给它的类型的参数作为它自己的参数.

那么我该如何编写模拟SocketClient工厂以传递给我的扫描仪?我什至无法弄清楚如何模拟一个带有参数的类！

解决方案

洞察力在于，您需要模拟的是socketClientFactory.然后将其设置为返回模拟SocketClient.

给出:

trait SocketClient {
  def frobnicate(): Unit
}

class ScannerBase(path: String)

class XScanner[T <: SocketClient](
  confPath: String = "/etc/default/configPath",
  socketClientFactory: String => T
) extends ScannerBase(confPath) {
  val socket = socketClientFactory("Some Socket Name")
  socket.frobnicate
}

(旁注-您无法使用confPath的默认值，因为socketClientFactory没有默认值).

然后，这应该会让您入门(这与Scala 2.9.x和ScalaMock2-与ScalaMock3的2.10.x会稍有不同，但差别不大):

import org.scalatest.FunSuite
import org.scalamock.scalatest.MockFactory
import org.scalamock.generated.GeneratedMockFactory

class ScannerTest extends FunSuite with MockFactory with GeneratedMockFactory {

  test("scanner") {
    val mockFactory = mockFunction[String, SocketClient]
    val mockClient = mock[SocketClient]
    mockFactory.expects("Some Socket Name").returning(mockClient)
    mockClient.expects.frobnicate
    val scanner = new XScanner("path/to/config", mockFactory)
  }
}

为完整起见，这是Scala 2.10.0和ScalaMock3中的相同测试:

import org.scalatest.FunSuite
import org.scalamock.scalatest.MockFactory

class ScannerTest extends FunSuite with MockFactory {

  test("scanner") {
    val mockFactory = mockFunction[String, SocketClient]
    val mockClient = mock[SocketClient]
    mockFactory.expects("Some Socket Name").returning(mockClient)
    (mockClient.frobnicate _).expects()
    val scanner = new XScanner("path/to/config", mockFactory)
  }
}

Full disclosure: I'm very new to mocking and mocking frameworks. I'm trying to use ScalaMock because it seemed like the 'default' mocking framework to use with ScalaTest but I am happy to use any other framework which is compatible with ScalaTest.

The problem: I've written in Scala a class that talks to a socket. The class has a type parameter of what sort of socket it is to talk to and one of it's arguments is a factory for creating sockets of that type. It has the signature:

class XScanner[T <: SocketClient](
  confPath: String = "/etc/default/configPath",
  socketClientFactory: String => T
) extends ScannerBase(path)

I would like to be able to write unit tests for this class by supplying a mock SocketClient so my test code doesn't have to connect to a real socket but I can't work out how to do this with ScalaMock.

My test code looks like this:

val t = new XScanner[SocketClient](confPath, (s: String) => mock[SocketClient])

Clearly that won't compile because SocketClient expects a path to the socket as an argument but I can't call mock[SocketClient(s)] because that's not a type and I can't call mock[SocketClient](s) because mock doesn't take the arguments of the type passed to it as it's own arguments.

So how can I write a mock SocketClient factory to pass to my Scanner? I can't even work out how to mock a class that takes arguments!

解决方案

The insight is that what you need to mock is socketClientFactory. And then set it up to return a mock SocketClient.

Given:

trait SocketClient {
  def frobnicate(): Unit
}

class ScannerBase(path: String)

class XScanner[T <: SocketClient](
  confPath: String = "/etc/default/configPath",
  socketClientFactory: String => T
) extends ScannerBase(confPath) {
  val socket = socketClientFactory("Some Socket Name")
  socket.frobnicate
}

(side note - your default value for confPath can never be used because there's no default value for socketClientFactory).

then this should get you started (this is with Scala 2.9.x and ScalaMock2 - 2.10.x with ScalaMock3 will be slightly different, but not much so):

import org.scalatest.FunSuite
import org.scalamock.scalatest.MockFactory
import org.scalamock.generated.GeneratedMockFactory

class ScannerTest extends FunSuite with MockFactory with GeneratedMockFactory {

  test("scanner") {
    val mockFactory = mockFunction[String, SocketClient]
    val mockClient = mock[SocketClient]
    mockFactory.expects("Some Socket Name").returning(mockClient)
    mockClient.expects.frobnicate
    val scanner = new XScanner("path/to/config", mockFactory)
  }
}

For completeness, here's the same test in Scala 2.10.0 and ScalaMock3:

import org.scalatest.FunSuite
import org.scalamock.scalatest.MockFactory

class ScannerTest extends FunSuite with MockFactory {

  test("scanner") {
    val mockFactory = mockFunction[String, SocketClient]
    val mockClient = mock[SocketClient]
    mockFactory.expects("Some Socket Name").returning(mockClient)
    (mockClient.frobnicate _).expects()
    val scanner = new XScanner("path/to/config", mockFactory)
  }
}

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