使用Mockito& amp;在Scala中使用泛型测试接口的向导 [英] Using Mockito & Guice to test interfaces with generics in Scala

问题描述

我是Scala的新手，在尝试对某些接口进行单元测试时，我就遇到了这个问题.

I am new to Scala, and I'm running into this problem when I'm trying to unit test some of my interfaces.

我具有方法的InputService特征

I have an InputService trait with method

def poll(parameters: HashMap[String, String]): Option[T]

其中T是通用的，因此InputService具有类型参数[T].

where T is generic, so InputService has a type parameter [T].

在我的模块中，我有

val inputService: InputService[String] = mock(classOf[InputService[String]])
bind[InputService[String]].toInstance(inputService)

在我的InputServiceTest中，我有

and in my InputServiceTest, I have

  var inputService: InputService[String] = _
  before {
    inputService = Guice.createInjector(new MockWatcherModule).getInstance(classOf[InputService[String]])
  }

但是问题是当我运行它时，它给了我这个错误

But the issue is when I run it, it gives me this error

Exception encountered when invoking run on a nested suite - Guice configuration errors:
1) No implementation for services.InputService was bound.
  while locating services.InputService

我认为这是因为它正在寻找绑定的services.InputService，但是它仅具有services.InputService [String].但是，当我只使用InputService而不是InputService [String]时，出现错误 Trait缺少类型参数.

I think it's because it's looking for services.InputService to bound, but it only has services.InputService[String]. However, when I just use InputService instead of InputService[String], I get the error Trait missing Type Parameter.

有什么建议吗?

事实证明，我可以使用scala-guice和KeyExtensions中的typeLiteral解决我的问题.谢谢塔维安！

Turns out that I can use typeLiteral from scala-guice and KeyExtensions to solve my issue. Thanks Tavian!

推荐答案

由于要进行擦除，因此在 getInstance(classOf [InputService [String]])调用中，您只是传递了 InputService.class .您需要传递 TypeLiteral 来编码通用类型信息.从一个快速的Google看来，

Due to type erasure, in the getInstance(classOf[InputService[String]]) call, you're just passing InputService.class. You need to pass a TypeLiteral instead to encode the generic type information. From a quick Google it looks like

import net.codingwell.scalaguice._
import net.codingwell.scalaguice.InjectorExtensions._

Guice.createInjector(new MockWatcherModule).instance[InputService[String]]

将起作用.

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