使用Mockito& Guice在Scala中测试与泛型的接口 [英] Using Mockito & Guice to test interfaces with generics in Scala

问题描述

我有一个InputService特性方法

  def poll（参数：HashMap [String，String]）：选项[T] 
  

其中T是通用的，所以InputService有一个类型参数[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

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

但问题是当我运行它时，它给了我这个错误

 调用嵌套套件运行时遇到异常 -  Guice配置错误：
 1）没有为services.InputService实现绑定。 
同时定位services.InputService 
  

我认为这是因为它正在寻找services.InputService绑定，但它只有services.InputService [String]。但是，当我只使用InputService而不是InputService [String]时，我得到错误 Trait缺少类型参数。

任何建议？

编辑：
原来我可以使用scala-guice和KeyExtensions中的typeLiteral来解决我的问题。感谢Tavian！

解决方案

由于类型擦除，在 getInstance（classOf [InputService [String]] ）调用，你只是传递 InputService.class 。您需要传递 TypeLiteral 来编码通用类型信息。从快速Google看起来像

  import net.codingwell.scalaguice._ 
 import net.codingwell.scalaguice.InjectorExtensions._ 
 
 Guice.createInjector（new MockWatcherModule）.instance [InputService [String]] 
  

会起作用。

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

I have an InputService trait with method

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

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

In my module, I have

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

and in my InputServiceTest, I have

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

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

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.

Any suggestions?

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

解决方案

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]]

will work.

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