问存根时出现空指针异常
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Stack Overflow用户

提问于 2020-11-02 11:07:54

回答 1查看 361关注 0票数 0

下午好，我在存根时有一个空指针异常

package com.micheladrien.android.fresquerappel

import android.app.Application
import androidx.arch.core.executor.testing.InstantTaskExecutorRule
import com.micheladrien.fresquerappel.R
import org.junit.Before
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith
import org.mockito.Mock    
import org.mockito.Mockito.`when`
import org.mockito.Mockito.mock
import org.mockito.junit.MockitoJUnitRunner


@RunWith(MockitoJUnitRunner::class)
class MainViewModelTest {

  @Rule
  @JvmField
  var instantTaskExecutorRule = InstantTaskExecutorRule()    

  @Mock
  val applicationMock: Application = mock(Application::class.java)
 
  @Before
  fun setUpTaskDetailViewModel() {
        `when`(applicationMock.getString(R.string.collage_climat)).thenReturn("Climat")
    }
    }

编辑:我需要存根函数when(applicationMock.getString(R.string.collage_climat)).thenReturn("Climat")，因为我的视图模型将从上下文中获取字符串。

根据这篇博文：https://codepills.com/2018/05/10/3-basic-mistakes-for-nullpointerexception-when-mock/我应该在返回时替换为when then (回答)，如果这是真的，为什么？

我已经测试过:将R.id值更改为一个不正确的数字。模拟before中的文件并在@Mock =>中使用=>声明时出现相同的错误

与前面的问题线程Mockito - NullpointerException when stubbing Method不同，我直接截断了这个方法。不截断另一个方法的对象的方法。

任何帮助都将不胜感激。

编辑:我要测试的虚拟机：

class MainViewModel(application: Application): AndroidViewModel(application), WaitingViewModel{

    private val _name = MutableLiveData<String>().apply {
        value = application.getString(R.string.collage_climat)
    }

    val name : LiveData<String> = _name

    override fun notifyNewCollage(collage_name: String) {
        _name.value = collage_name
    }

}

如果你想检查Mockito的版本，这里是gradle：

dependencies {
implementation fileTree(dir: "libs", include: ["*.jar"])
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
implementation 'androidx.core:core-ktx:1.3.2'
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'com.google.android.material:material:1.2.1'
implementation 'androidx.constraintlayout:constraintlayout:2.0.3'
def navigation_version = '2.3.1'
implementation "androidx.navigation:navigation-fragment-ktx:$navigation_version"
implementation "androidx.navigation:navigation-ui-ktx:$navigation_version"
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
implementation "androidx.navigation:navigation-fragment:$navigation_version"
implementation "androidx.navigation:navigation-ui:$navigation_version"
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
implementation 'androidx.annotation:annotation:1.1.0'
implementation 'androidx.recyclerview:recyclerview:1.1.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
implementation 'il.co.theblitz:observablecollections:1.4.2'
def espressocore_version = '3.3.0'
androidTestImplementation "androidx.test.espresso:espresso-core:$espressocore_version"
androidTestImplementation "androidx.test.espresso:espresso-core:$espressocore_version"
androidTestImplementation "android.arch.core:core-testing:$lifecycle_version"
def mockito_version = '3.5.5' // For local unit tests on your development machine (also tested on 3.3.3)
testImplementation "org.mockito:mockito-core:$mockito_version" // For instrumentation tests on Android devices and emulators
androidTestImplementation "org.mockito:mockito-android:$mockito_version"
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test:rules:1.0.2'

}