在Scala中理解模拟 [英] Mock for comprehension in scala

问题描述

我有这段代码

   for (element <- table.find;
     Right(info) = exceptionManager(mapper.getInfoFromDbObject(element)))
yield info

，我想对其进行单元测试.我想模拟table.find以返回我想要的元素序列.我曾尝试模拟Iterator接口的hasNext()和next()方法，但似乎无法正常工作.哪种方法可以模拟a进行理解?

and I would like to unit test it. I want to mock table.find in order to return a sequence of element that I want. I have tried mocking hasNext() and next() methods of Iterator interface but it seems it is not working. Which is the method to mock a for comprehension?

推荐答案

用于理解的内容均转换为map，flatMap，filter方法调用.因此，您至少应该嘲笑它们.

Each for comprehension is translated to map, flatMap, filter method calls. So you should mock at least them.

您可以在此处找到更多信息(例如):

You can find more information here (for example):

http://www.lambdascale.com/2010/12/the-adventures-of-a-java-developer-in-monadland/

当然，您会在在Scala书中编程中找到深入的解释.

And of course you will find deep explanation in Programming in Scala book.

但是正如 Dave Griffith 所说，您可以自己初始化新的Iterator.这是一个使用 Mockito 和 ScalaTest :

But as Dave Griffith said, you can just initialize new Iterator yourself. Here is an example that uses Mockito and ScalaTest:

val table = mock[TableClass]
when(table find) thenReturn Iterator(new ModelObject(1), new ModelObject(2))

编辑1

正如 Daniel 所注意到的，出于理解的考虑，现在不推荐使用filter方法.相反，您应该使用withFilter.有关更多信息，请参见此线程:

Edit 1

As Daniel noticed, filter method is now deprecated in for comprehensions. Instead you should use withFilter. For more information you can look in this thread:

http://scala-programming -language.1934581.n4.nabble.com/Rethinking-filter-td2009215.html#a2009218

和这个相关的SO问题:

and this related SO question:

从过滤器移至withFilter的指南?

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