Question

因此，我尝试使用Mockito为我的Hadoop映射功能创建一个单元测试。我已经正确创建了Mapper类：

class XmlMapper extends Mapper[LongWritable, Text, Text, LongWritable] {

    override def map(key: LongWritable, value: Text, context: Mapper[LongWritable, Text, Text, LongWritable]#Context): Unit = {
        //does stuff
    }
}

然后我进行了以下测试：

import org.apache.hadoop.io.{LongWritable, Text}
import org.scalatest.FlatSpec
import org.scalatest.mockito.MockitoSugar
import org.mockito.Mockito.verify
import org.mockito.Mockito.times

class XmlMapperTest extends FlatSpec with MockitoSugar {

    "XmlMapper" should "output" in {
        val mapper = new XmlMapper
        val context = mock[mapper.Context]
        //so far does nothing yet
    }
}

但是出现以下错误：

- should output *** FAILED ***
[info]   org.mockito.exceptions.base.MockitoException: Mockito cannot mock this class: class org.apache.hadoop.mapreduce.Mapper$Context.
[info]
[info] Mockito can only mock non-private & non-final classes.
[info] If you're not sure why you're getting this error, please report to the mailing list.

这没有意义，因为Mapper.Context是公共抽象类。

这是总堆栈跟踪：

[info] Underlying exception : java.lang.UnsupportedOperationException: Cannot define class using reflection
[info]   at org.scalatest.mockito.MockitoSugar.mock(MockitoSugar.scala:73)
[info]   at org.scalatest.mockito.MockitoSugar.mock$(MockitoSugar.scala:72)
[info]   at XmlMapperTest.mock(XmlMapperTest.scala:7)
[info]   at XmlMapperTest.$anonfun$new$1(XmlMapperTest.scala:11)
[info]   at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:22)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:20)

Answer 1

考虑到您正在使用Scala，您似乎正在使用旧版本的Mockito-core，强烈建议您改用最新版本的mockito-scala

此外，只要有可能，作为一种好的实践，您应该避免嘲笑您不拥有的类。更好的方法是将与第三方的交互包装在一个类（或一组类）中，并进行集成测试以证明它们按预期工作。

在系统的其余部分上，您注入了这些类，因此，为了进行测试，您对上述类进行了模拟，这使您可以控制（并简化）公开的接口，并在第三版的未来版本中最大程度地减少中断方lib更改其API。

有关更多详细信息，请在Mockito博客上查看此StackOverflow answer和此post

Mockito无法模拟Hadoop Mapper上下文

1 个答案: