PowerMockito Spy：使用CannotStubVoidMethodWithReturnValue调用实方法结果

Question

我开始把头撞到墙上，但我完全不明白如何在间谍类上调用真正的方法。

长话短说，我正在监视我的测试类，以存根一个私有方法。然后我想调用测试类的real void方法，但它说

testedmethod是一个空方法，不能用返回值来存根它！

问题是，我不需要把它存根。我也尝试过doCallRealMethod（），没有用。

我正在使用静态编程语言和Android Studio为我的Android项目运行一些单元测试。我想测试以下类：

class MyClass {
   fun persistDeviceData(deviceInfo: DeviceInfo, saveCallback: SaveCallback) {
       val deviceObject = getDeviceObject()
          // some setters from deviceInfo here
       deviceObject.saveInBackground(callback)
   }

   // This method is created for unit testing purposes
   private fun getDeviceObject(): MyDeviceObject{
       return MyDeviceObject("someStringArgument")
   }
}

这是测试课

import io.kotlintest.KTestJUnitRunner
import io.kotlintest.specs.BehaviorSpec
import junit.framework.Assert
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 org.powermock.modules.junit4.PowerMockRunnerDelegate

@RunWith(PowerMockRunner::class)
@PowerMockRunnerDelegate(KTestJUnitRunner::class)
@PrepareForTest(MyClass::class)
class MyClassTest: BehaviorSpec(){

    init {

        val deviceObject = PowerMockito.mock(MyDeviceObject::class.java)
        val myClassTest = PowerMockito.spy(MyClass())
        // Mocking private method call
        PowerMockito.doReturn(deviceObject).`when`(testedRepo,
                PowerMockito.method(
                        MyClass::class.java,
                        "getDeviceObject"))
        val a = SaveCallback { // Callback handling here }
        // Calling REAL method of spy class. Here it fails
        myClassTest.persistDeviceData(DeviceInfo(), a)
        Assert.assertTrue(true)
    }

}

在下面一行调用real方法时，测试失败

MyClassTest.persistDeviceData（DeviceInfo（）， a）

这是错误堆栈跟踪

org.mockito.exceptions.misusing.Cannot StubVoidmetodwith ReportnValue：'坚持设备数据'是一个空方法，它不能用一个返回值来存根！空通常用Throwable来存根：doThrow（异常）。当（mock）。一些Voidmethod（）；如果你需要设置空方法什么也不做，你可以使用：do没什么（）。当（mock）。一些Voidmethod（）；有关更多信息，请查看Mockito.do没什么（）的javadocs。

如果你不确定为什么会出现上述错误，请继续阅读。由于语法的性质，上述问题可能会出现，因为：1。您尝试存根的方法已重载。确保调用的是正确的重载版本。2.在考试的某个地方，你正在截取最后的方法。抱歉，Mockito不验证/stub final方法。3.间谍使用when（spy.foo（））进行存根。then（）语法。使用doReturn | Throw（）方法系列，对存根间谍更安全。更多关于Mockito的javadocs。spy（）方法。4.不支持对非公共父类声明的模拟方法。

at MyClassTest.<init>(MyClass.kt:46)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at java.lang.Class.newInstance(Class.java:442)
at io.kotlintest.KTestJUnitRunner.<init>(KTestJUnitRunner.kt:9)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.powermock.reflect.internal.WhiteboxImpl.createInstance(WhiteboxImpl.java:1414)
at org.powermock.reflect.internal.WhiteboxImpl.invokeConstructor(WhiteboxImpl.java:1262)
at org.powermock.reflect.Whitebox.invokeConstructor(Whitebox.java:497)
at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner$1.call(DelegatingPowerMockRunner.java:101)
at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner$1.call(DelegatingPowerMockRunner.java:97)
at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.withContextClassLoader(DelegatingPowerMockRunner.java:132)
at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.createDelegate(DelegatingPowerMockRunner.java:96)
at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.<init>(DelegatingPowerMockRunner.java:64)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:165)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:47)
at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.createTestDelegators(AbstractTestSuiteChunkerImpl.java:107)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.<init>(JUnit4TestSuiteChunkerImpl.java:69)
at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.<init>(AbstractCommonPowerMockRunner.java:36)
at org.powermock.modules.junit4.PowerMockRunner.<init>(PowerMockRunner.java:34)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:104)
at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:86)
at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)
at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:33)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:49)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Answer 1

回答我自己的问题——我错误地使用了PowerMockito的。when（）方法。以下是有效的代码：

@RunWith(PowerMockRunner::class)
@PrepareForTest(MyClass::class, DeviceObject::class)
class DeviceRepositoryImplTest{

    private val testedRepo = PowerMockito.spy(MyClass())
    private val deviceObject = PowerMockito.mock(DeviceObject())

    @Test
    fun persistDeviceData_ok(){
        // Mocking private method
        PowerMockito.`when`<ParseObject>(testedRepo,
            PowerMockito.method(
                        MyClass::class.java,
                            "getDeviceObject")).withNoArguments().thenReturn(deviceObject)

        // Creating callback for tested method
        val callback = SaveCallback {
            ...
        }

        ...

        testedRepo.persistDeviceData(DeviceInfo(), callback)

    }