在 Scala 中调用静态模拟时 NotAMockException

Question

我正在尝试在Scala中使用PowerMockito来绕过对scala.io.Source.fromURL的调用，这是类Source中的静态方法。我已经非常接近让它工作，但我一直在NotAMockException.

import com.sun.xml.internal.messaging.saaj.util.ByteInputStream
import org.junit.Test
import org.junit.runner.RunWith
import org.mockito.Mockito
import org.powermock.api.mockito.PowerMockito
import org.powermock.core.classloader.annotations.PrepareForTest
import org.powermock.modules.junit4.PowerMockRunner
import scala.io.BufferedSource
import scala.io.Source
@RunWith(classOf[PowerMockRunner])
@PrepareForTest(Array(classOf[Source]))
class UtilsTest {
  @Test def someTest() {
    PowerMockito.mockStatic(classOf[Source])
    val a = "hello"
    Mockito.doReturn(
      new BufferedSource(
        new ByteInputStream(a.getBytes, 6), 6))
      .when(Source).fromURL(anyString)
  }
}

我在when行上收到以下错误：

org.mockito.exceptions.misusing.NotAMockException: 
Argument passed to when() is not a mock!
Example of correct stubbing:
    doThrow(new RuntimeException()).when(mock).someMethod();

知道我做错了什么吗？我把这门课模拟得对了，不是吗？

[编辑]

我的build.sbt(显然瘦了(：

import _root_.sbtassembly.AssemblyPlugin.autoImport._
name := "yahoo-cml"
organization := "com.yahoo"
version := "0.1.0"
scalaVersion := "2.11.8"
lazy val yahooNexusRepo = "Nexus" at "http://pp-nexus.office.yahoo.com/content/groups/public"
lazy val cpArchiva = "cpArchiva" at "http://cp-archiva.office.yahoo.com"
lazy val yahooRepo = "NexusXP" at
  "http://pp-nexus.office.yahoo.com/content/repositories/yahoo-releases"
fullResolvers ++= Seq(
  yahooNexusRepo,
  cpArchiva,
  yahooRepo
)
libraryDependencies ++= Seq(
  // scalatest is exlcuded due to conflict with testing libraries.
  "org.apache.spark" %% "spark-core" % "2.1.0" % "provided"
    exclude("org.scalatest", "scalatest_2.11"),
  "org.apache.spark" %% "spark-sql" % "2.1.0" % "provided",
  "org.apache.spark" % "spark-hive_2.11" % "2.1.0" % "provided",
  "org.apache.spark" % "spark-mllib_2.11" % "2.1.0" % "provided",
  // Command line parser
  "com.frugalmechanic" %% "scala-optparse" % "1.1.1",
  //  SBT Junit is supported through junit-interface
  "com.novocode" % "junit-interface" % "0.11" % "test",
  // scalacheck added explicitely to avoid below error due to higher version of scalacheck.
  // "org.scalacheck" % "scalacheck_2.11" % "1.12.5" % "test",
  //  ScalaTest is test framework for scala
  // "org.scalatest" % "scalatest_2.11" % "3.0.1" % "test",
  //  Added as this is optional dependency for generating HTML reports in scalatest.
  "org.pegdown" % "pegdown" % "1.6.0" % "test",
  //  spark test framework.
  "com.holdenkarau" % "spark-testing-base_2.11" % "2.1.0_0.6.0" % "test",
  // mockito
  "org.powermock" % "powermock-api-mockito" % "1.7.4" % Test,
  "org.powermock" % "powermock-core" % "1.7.4" % Test,
  "org.powermock" % "powermock-module-junit4" % "1.7.4" % Test,
  "org.mockito" % "mockito-core" % "1.10.19" % Test,
  "com.novocode" % "junit-interface" % "0.11" % Test,
  // fastUtil efficient type specific collection library
  "it.unimi.dsi" % "fastutil" % "8.2.1"
)
// Create a default Scala style task to run with compile
(scalastyleConfig in Compile) := baseDirectory.value / "scalastyle-config.xml"
lazy val compileScalastyle = taskKey[Unit]("compileScalastyle")
compileScalastyle := org.scalastyle.sbt.ScalastylePlugin.scalastyle.in(Compile).toTask("").value
(compile in Compile) <<= (compile in Compile) dependsOn compileScalastyle
// Create a default Scala style task to run with tests
lazy val testScalastyle = taskKey[Unit]("testScalastyle")
testScalastyle := org.scalastyle.sbt.ScalastylePlugin.scalastyle.in(Test).toTask("").value
(test in Test) <<= (test in Test) dependsOn testScalastyle

// Configure Java source code style checking plugin.
checkstyleConfigLocation := CheckstyleConfigLocation.File("checkstyle-config.xml")
checkstyleSeverityLevel := Some(CheckstyleSeverityLevel.Error)
(checkstyle in Compile) <<= (checkstyle in Compile) triggeredBy (compile in Compile)
(checkstyle in Test) <<= (checkstyle in Test) triggeredBy (compile in Test)
// Specifying scalatest style traits for uniformity.
// All scala test classes should extend this style ONLY.
testOptions in Test += Tests.Argument(TestFrameworks.ScalaTest, "-y", "org.scalatest.PropSpec")
testOptions in Test += Tests.Argument(TestFrameworks.JUnit, "-v")
testOptions in Test ++= Seq(Tests.Argument(TestFrameworks.ScalaTest, "-o"),
  Tests.Argument(TestFrameworks.ScalaTest, "-h", "target/scala-2.11/scalatest-reports"))
testOptions in Test += Tests.Argument("-oD") // test execution time recording.
parallelExecution in Test := false
fork in Test := true
javaOptions ++= Seq("-Xms512M", "-Xmx2048M",
  "-XX:MaxPermSize=2048M", "-XX:+CMSClassUnloadingEnabled")
// Coverage settings
// Coverage is disabled by default to avoid Scoverage's runtime dependency in application jar.
// Enable coverage explicitly when needed. like,
//   sbt coverage clean test coverageReport
// Do not use coverage when publishing jar
// coverageEnabled := true
coverageMinimum := 70
coverageFailOnMinimum := false
coverageHighlighting := true
// Do not include scala librabries in assembly jar.
assemblyOption in assembly :=
  (assemblyOption in assembly).value.copy(includeScala = false)
// assembly name here should match to same generated by publishLocal.
assemblyJarName := "cml_" + scalaBinaryVersion.value + "-assembly.jar"
// addArtifact(artifact in (Compile, assembly), assembly)

// https://books.sonatype.com/nexus-book/reference/sbt.html
// SBT publish settings.
credentials += Credentials("Sonatype Nexus Repository Manager",
  "pp-nexus.office.yahoo.com",
  "yahooUser", "password")
publishTo <<= version { v: String =>
  val nexus = "http://pp-nexus.office.yahoo.com/"
  if (v.trim.endsWith("SNAPSHOT")) {
    Some("snapshots" at nexus + "content/repositories/yahoo-snapshots/")
  } else {
    Some("releases" at nexus + "content/repositories/yahoo-releases/")
  }
}

Answer 1

这里有两点需要注意。

• 作为一般规则，object会妨碍您的测试能力，因此，如果他们扩展了一个特征，您应该耦合到该特征，然后将object作为默认实现注入，或者您只需将它们包装在您自己的特征中并耦合到该特征中。

模拟主要用于替换你自己的类/特征，

• 而不是第三方的类/特征，所以同样，这里最好的办法是将该调用包装到你自己的组件中(并为其做一个集成测试(，然后耦合到它，这将允许你轻松模拟它。