ViewModel UI 使用 JUnit 5 进行测试
ViewModel UI testing with JUnit 5
我正在尝试向我的应用添加一些单元测试，但我发现在向我的 ViewModel 的 classes 添加测试时遇到一些问题。
我使用 androidx. lifecycle 库创建了一个标准的 ViewModel class。
在这些 ViewModel classes 中，我启动了一个协程来进行 API 调用并检索一些数据。
为此，我创建了一个 ViewModel 扩展函数来调用用例以最终进行 API 调用。
fun ViewModel.execute(useCase: suspend () -> Unit) {
viewModelScope.launch { useCase() }
}
如您所见，我正在使用 viewModelScope 来避免一些样板代码，而且它工作得很好。
此外，我将项目配置为使用 JUnit5 和 Mockito。一切顺利，直到我尝试为 ViewModel class.
创建一些测试
因为我正在使用 LiveData，所以我创建了一个扩展，以便能够捕获 LiveData 对象的值。像这样：
import android.annotation.SuppressLint
import androidx.arch.core.executor.ArchTaskExecutor
import androidx.arch.core.executor.TaskExecutor
import org.junit.jupiter.api.extension.AfterEachCallback
import org.junit.jupiter.api.extension.BeforeEachCallback
import org.junit.jupiter.api.extension.ExtensionContext
/**
* JUnit5 extension to be able to test LiveData objects
*/
class InstantExecutorExtension : BeforeEachCallback, AfterEachCallback {
/**
* sets a delegate before each test that updates LiveData immediately on the calling thread
*/
@SuppressLint("RestrictedApi")
override fun beforeEach(context: ExtensionContext?) {
ArchTaskExecutor.getInstance()
.setDelegate(object : TaskExecutor() {
override fun executeOnDiskIO(runnable: Runnable) = runnable.run()
override fun postToMainThread(runnable: Runnable) = runnable.run()
override fun isMainThread(): Boolean = true
})
}
/**
* Remove delegate after each test, to avoid influencing other tests
*/
@SuppressLint("RestrictedApi")
override fun afterEach(context: ExtensionContext?) {
ArchTaskExecutor.getInstance().setDelegate(null)
}
}
好的，有了这个，我已经阅读了一些关于如何设置测试以能够测试使用协程的 ViewModel classes 的帖子。他们中的很多人解释创建一个规则，添加一个 TestCoroutine，以便能够启动协程。
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.test.TestCoroutineDispatcher
import kotlinx.coroutines.test.resetMain
import kotlinx.coroutines.test.setMain
import org.junit.rules.TestWatcher
import org.junit.runner.Description
@ExperimentalCoroutinesApi
class CoroutineTestRule(private val dispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()) :
TestWatcher() {
override fun starting(description: Description?) {
super.starting(description)
Dispatchers.setMain(dispatcher)
}
override fun finished(description: Description?) {
super.finished(description)
Dispatchers.resetMain()
}
}
我只需要将规则添加到我的 ViewModel 测试文件中，我就可以测试使用协程和 LiveData 的 ViewModel classes，但是，当我启动我的测试时。我正在检索一个异常，内容如下：
Exception in thread "Test worker @coroutine#1" java.lang.IllegalStateException: Module with the Main dispatcher had failed to initialize. For tests Dispatchers.setMain from kotlinx-coroutines-test module can be used
at kotlinx.coroutines.internal.MissingMainCoroutineDispatcher.missing(MainDispatchers.kt:113)
at kotlinx.coroutines.internal.MissingMainCoroutineDispatcher.isDispatchNeeded(MainDispatchers.kt:94)
at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:319)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:30)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable$default(Cancellable.kt:25)
at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:110)
at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:56)
at kotlinx.coroutines.BuildersKt.launch(Unknown Source)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default(Builders.common.kt:47)
at kotlinx.coroutines.BuildersKt.launch$default(Unknown Source)
at com.example.core.extensions.ViewModelExtensionKt.execute(ViewModelExtension.kt:8)
at com.example.baseapplication.presentation.main.firstView.FirstViewModel.getSampleData(FirstViewModel.kt:21)
at com.example.baseapplication.presentation.main.firstView.FirstViewModel.initialize(FirstViewModel.kt:17)
at com.example.baseapplication.presentation.FirstViewModelTest$getSampleData should return sample data .invokeSuspend(FirstViewModelTest.kt:42)
at com.example.baseapplication.presentation.FirstViewModelTest$getSampleData should return sample data .invoke(FirstViewModelTest.kt)
at com.example.baseapplication.presentation.FirstViewModelTest$getSampleData should return sample data .invoke(FirstViewModelTest.kt)
at kotlinx.coroutines.test.TestBuildersKt$runBlockingTest$deferred.invokeSuspend(TestBuilders.kt:50)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
at kotlinx.coroutines.test.TestCoroutineDispatcher.dispatch(TestCoroutineDispatcher.kt:50)
at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:322)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:30)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable$default(Cancellable.kt:25)
at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:110)
at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.async(Builders.common.kt:91)
at kotlinx.coroutines.BuildersKt.async(Unknown Source)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.async$default(Builders.common.kt:82)
at kotlinx.coroutines.BuildersKt.async$default(Unknown Source)
at kotlinx.coroutines.test.TestBuildersKt.runBlockingTest(TestBuilders.kt:49)
at kotlinx.coroutines.test.TestBuildersKt.runBlockingTest(TestBuilders.kt:80)
at com.example.baseapplication.presentation.FirstViewModelTest.getSampleData_should_return_sample_data_$lambda-1$lambda-0(FirstViewModelTest.kt:39)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.lambda$execute[=14=](DynamicTestTestDescriptor.java:52)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.api.extension.InvocationInterceptor.interceptDynamicTest(InvocationInterceptor.java:161)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.lambda$execute(DynamicTestTestDescriptor.java:58)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptorCall.lambda$ofVoid[=14=](InvocationInterceptorChain.java:78)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.execute(DynamicTestTestDescriptor.java:57)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.execute(DynamicTestTestDescriptor.java:31)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.NodeTestTask$DefaultDynamicTestExecutor.execute(NodeTestTask.java:212)
at org.junit.platform.engine.support.hierarchical.NodeTestTask$DefaultDynamicTestExecutor.execute(NodeTestTask.java:192)
at java.base/java.util.Optional.ifPresent(Optional.java:183)
at org.junit.jupiter.engine.descriptor.TestFactoryTestDescriptor.lambda$invokeTestMethod(TestFactoryTestDescriptor.java:106)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestFactoryTestDescriptor.invokeTestMethod(TestFactoryTestDescriptor.java:93)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:143)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:143)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute[=14=](EngineExecutionOrchestrator.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:99)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access[=14=]0(JUnitPlatformTestClassProcessor.java:79)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:75)
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:61)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
at com.sun.proxy.$Proxy2.stop(Unknown Source)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.stop(TestWorker.java:135)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:414)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.ManagedExecutorImpl.run(ManagedExecutorImpl.java:48)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.RuntimeException: Method getMainLooper in android.os.Looper not mocked. See http://g.co/androidstudio/not-mocked for details.
at android.os.Looper.getMainLooper(Looper.java)
at kotlinx.coroutines.android.AndroidDispatcherFactory.createDispatcher(HandlerDispatcher.kt:55)
at kotlinx.coroutines.android.AndroidDispatcherFactory.createDispatcher(HandlerDispatcher.kt:52)
at kotlinx.coroutines.internal.MainDispatchersKt.tryCreateDispatcher(MainDispatchers.kt:57)
at kotlinx.coroutines.test.internal.TestMainDispatcher.getDelegate(MainTestDispatcher.kt:19)
at kotlinx.coroutines.test.internal.TestMainDispatcher.getImmediate(MainTestDispatcher.kt:32)
at androidx.lifecycle.ViewModelKt.getViewModelScope(ViewModel.kt:42)
... 117 more
我不知道我是否遗漏了什么，但我无法 运行 ViewModel 测试并 运行 它们成功。
我刚刚能够 运行 测试成功，但是它将 Dispatcher 设置为 Unconfined，但这不是我想要做的，也不是推荐的方法。
好的，我找到问题了。我使用的是 JUnit 4 解决方案，而不是 JUnit 5 库。
- 我创建的扩展是正确的，每当我们使用 LiveData 对象时，我们应该立即更新 LiveData 对象。
- 我是如何为测试用例设置协程范围的，这是错误的。我正在使用 JUnit 4 的解决方案，但我应该修改代码以使其与 JUnit5 相同。
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.test.TestCoroutineDispatcher
import kotlinx.coroutines.test.TestCoroutineScope
import kotlinx.coroutines.test.resetMain
import kotlinx.coroutines.test.setMain
import org.junit.jupiter.api.extension.AfterEachCallback
import org.junit.jupiter.api.extension.BeforeEachCallback
import org.junit.jupiter.api.extension.ExtensionContext
@ExperimentalCoroutinesApi
class CoroutinesTestExtension(
private val dispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()
) : BeforeEachCallback, AfterEachCallback, TestCoroutineScope by TestCoroutineScope(dispatcher) {
/**
* Set TestCoroutine dispatcher as main
*/
override fun beforeEach(context: ExtensionContext?) {
Dispatchers.setMain(dispatcher)
}
override fun afterEach(context: ExtensionContext?) {
Dispatchers.resetMain()
}
}
JUnit 5 beforeEach(ExtensionContext) 和 afterEach(ExtensionContext) 等同于 JUnit 4 starting(Description) 和 finished(Description)。在每个用 @Test 注释的测试方法之前和之后调用它们。上面的扩展将在每次测试之前模拟 Dispatchers.Main 并在之后重置模拟。
之后，我只需要将我的扩展添加到我的测试文件中，如下所示：
@ExtendWith(InstantExecutorExtension::class, CoroutinesTestExtension::class)
我正在尝试向我的应用添加一些单元测试，但我发现在向我的 ViewModel 的 classes 添加测试时遇到一些问题。
我使用 androidx. lifecycle 库创建了一个标准的 ViewModel class。
在这些 ViewModel classes 中，我启动了一个协程来进行 API 调用并检索一些数据。
为此，我创建了一个 ViewModel 扩展函数来调用用例以最终进行 API 调用。
fun ViewModel.execute(useCase: suspend () -> Unit) {
viewModelScope.launch { useCase() }
}
如您所见，我正在使用 viewModelScope 来避免一些样板代码，而且它工作得很好。
此外，我将项目配置为使用 JUnit5 和 Mockito。一切顺利，直到我尝试为 ViewModel class.
创建一些测试因为我正在使用 LiveData，所以我创建了一个扩展，以便能够捕获 LiveData 对象的值。像这样：
import android.annotation.SuppressLint
import androidx.arch.core.executor.ArchTaskExecutor
import androidx.arch.core.executor.TaskExecutor
import org.junit.jupiter.api.extension.AfterEachCallback
import org.junit.jupiter.api.extension.BeforeEachCallback
import org.junit.jupiter.api.extension.ExtensionContext
/**
* JUnit5 extension to be able to test LiveData objects
*/
class InstantExecutorExtension : BeforeEachCallback, AfterEachCallback {
/**
* sets a delegate before each test that updates LiveData immediately on the calling thread
*/
@SuppressLint("RestrictedApi")
override fun beforeEach(context: ExtensionContext?) {
ArchTaskExecutor.getInstance()
.setDelegate(object : TaskExecutor() {
override fun executeOnDiskIO(runnable: Runnable) = runnable.run()
override fun postToMainThread(runnable: Runnable) = runnable.run()
override fun isMainThread(): Boolean = true
})
}
/**
* Remove delegate after each test, to avoid influencing other tests
*/
@SuppressLint("RestrictedApi")
override fun afterEach(context: ExtensionContext?) {
ArchTaskExecutor.getInstance().setDelegate(null)
}
}
好的，有了这个，我已经阅读了一些关于如何设置测试以能够测试使用协程的 ViewModel classes 的帖子。他们中的很多人解释创建一个规则，添加一个 TestCoroutine，以便能够启动协程。
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.test.TestCoroutineDispatcher
import kotlinx.coroutines.test.resetMain
import kotlinx.coroutines.test.setMain
import org.junit.rules.TestWatcher
import org.junit.runner.Description
@ExperimentalCoroutinesApi
class CoroutineTestRule(private val dispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()) :
TestWatcher() {
override fun starting(description: Description?) {
super.starting(description)
Dispatchers.setMain(dispatcher)
}
override fun finished(description: Description?) {
super.finished(description)
Dispatchers.resetMain()
}
}
我只需要将规则添加到我的 ViewModel 测试文件中，我就可以测试使用协程和 LiveData 的 ViewModel classes，但是，当我启动我的测试时。我正在检索一个异常，内容如下：
Exception in thread "Test worker @coroutine#1" java.lang.IllegalStateException: Module with the Main dispatcher had failed to initialize. For tests Dispatchers.setMain from kotlinx-coroutines-test module can be used
at kotlinx.coroutines.internal.MissingMainCoroutineDispatcher.missing(MainDispatchers.kt:113)
at kotlinx.coroutines.internal.MissingMainCoroutineDispatcher.isDispatchNeeded(MainDispatchers.kt:94)
at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:319)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:30)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable$default(Cancellable.kt:25)
at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:110)
at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:56)
at kotlinx.coroutines.BuildersKt.launch(Unknown Source)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default(Builders.common.kt:47)
at kotlinx.coroutines.BuildersKt.launch$default(Unknown Source)
at com.example.core.extensions.ViewModelExtensionKt.execute(ViewModelExtension.kt:8)
at com.example.baseapplication.presentation.main.firstView.FirstViewModel.getSampleData(FirstViewModel.kt:21)
at com.example.baseapplication.presentation.main.firstView.FirstViewModel.initialize(FirstViewModel.kt:17)
at com.example.baseapplication.presentation.FirstViewModelTest$getSampleData should return sample data .invokeSuspend(FirstViewModelTest.kt:42)
at com.example.baseapplication.presentation.FirstViewModelTest$getSampleData should return sample data .invoke(FirstViewModelTest.kt)
at com.example.baseapplication.presentation.FirstViewModelTest$getSampleData should return sample data .invoke(FirstViewModelTest.kt)
at kotlinx.coroutines.test.TestBuildersKt$runBlockingTest$deferred.invokeSuspend(TestBuilders.kt:50)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
at kotlinx.coroutines.test.TestCoroutineDispatcher.dispatch(TestCoroutineDispatcher.kt:50)
at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:322)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:30)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable$default(Cancellable.kt:25)
at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:110)
at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.async(Builders.common.kt:91)
at kotlinx.coroutines.BuildersKt.async(Unknown Source)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.async$default(Builders.common.kt:82)
at kotlinx.coroutines.BuildersKt.async$default(Unknown Source)
at kotlinx.coroutines.test.TestBuildersKt.runBlockingTest(TestBuilders.kt:49)
at kotlinx.coroutines.test.TestBuildersKt.runBlockingTest(TestBuilders.kt:80)
at com.example.baseapplication.presentation.FirstViewModelTest.getSampleData_should_return_sample_data_$lambda-1$lambda-0(FirstViewModelTest.kt:39)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.lambda$execute[=14=](DynamicTestTestDescriptor.java:52)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.api.extension.InvocationInterceptor.interceptDynamicTest(InvocationInterceptor.java:161)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.lambda$execute(DynamicTestTestDescriptor.java:58)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptorCall.lambda$ofVoid[=14=](InvocationInterceptorChain.java:78)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.execute(DynamicTestTestDescriptor.java:57)
at org.junit.jupiter.engine.descriptor.DynamicTestTestDescriptor.execute(DynamicTestTestDescriptor.java:31)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.NodeTestTask$DefaultDynamicTestExecutor.execute(NodeTestTask.java:212)
at org.junit.platform.engine.support.hierarchical.NodeTestTask$DefaultDynamicTestExecutor.execute(NodeTestTask.java:192)
at java.base/java.util.Optional.ifPresent(Optional.java:183)
at org.junit.jupiter.engine.descriptor.TestFactoryTestDescriptor.lambda$invokeTestMethod(TestFactoryTestDescriptor.java:106)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestFactoryTestDescriptor.invokeTestMethod(TestFactoryTestDescriptor.java:93)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:143)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:143)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:129)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively(NodeTestTask.java:127)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute[=14=](EngineExecutionOrchestrator.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:99)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access[=14=]0(JUnitPlatformTestClassProcessor.java:79)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:75)
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:61)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
at com.sun.proxy.$Proxy2.stop(Unknown Source)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.stop(TestWorker.java:135)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:414)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.ManagedExecutorImpl.run(ManagedExecutorImpl.java:48)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.RuntimeException: Method getMainLooper in android.os.Looper not mocked. See http://g.co/androidstudio/not-mocked for details.
at android.os.Looper.getMainLooper(Looper.java)
at kotlinx.coroutines.android.AndroidDispatcherFactory.createDispatcher(HandlerDispatcher.kt:55)
at kotlinx.coroutines.android.AndroidDispatcherFactory.createDispatcher(HandlerDispatcher.kt:52)
at kotlinx.coroutines.internal.MainDispatchersKt.tryCreateDispatcher(MainDispatchers.kt:57)
at kotlinx.coroutines.test.internal.TestMainDispatcher.getDelegate(MainTestDispatcher.kt:19)
at kotlinx.coroutines.test.internal.TestMainDispatcher.getImmediate(MainTestDispatcher.kt:32)
at androidx.lifecycle.ViewModelKt.getViewModelScope(ViewModel.kt:42)
... 117 more
我不知道我是否遗漏了什么，但我无法 运行 ViewModel 测试并 运行 它们成功。
我刚刚能够 运行 测试成功，但是它将 Dispatcher 设置为 Unconfined，但这不是我想要做的，也不是推荐的方法。
好的，我找到问题了。我使用的是 JUnit 4 解决方案，而不是 JUnit 5 库。
- 我创建的扩展是正确的，每当我们使用 LiveData 对象时，我们应该立即更新 LiveData 对象。
- 我是如何为测试用例设置协程范围的，这是错误的。我正在使用 JUnit 4 的解决方案，但我应该修改代码以使其与 JUnit5 相同。
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.test.TestCoroutineDispatcher
import kotlinx.coroutines.test.TestCoroutineScope
import kotlinx.coroutines.test.resetMain
import kotlinx.coroutines.test.setMain
import org.junit.jupiter.api.extension.AfterEachCallback
import org.junit.jupiter.api.extension.BeforeEachCallback
import org.junit.jupiter.api.extension.ExtensionContext
@ExperimentalCoroutinesApi
class CoroutinesTestExtension(
private val dispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()
) : BeforeEachCallback, AfterEachCallback, TestCoroutineScope by TestCoroutineScope(dispatcher) {
/**
* Set TestCoroutine dispatcher as main
*/
override fun beforeEach(context: ExtensionContext?) {
Dispatchers.setMain(dispatcher)
}
override fun afterEach(context: ExtensionContext?) {
Dispatchers.resetMain()
}
}
JUnit 5 beforeEach(ExtensionContext) 和 afterEach(ExtensionContext) 等同于 JUnit 4 starting(Description) 和 finished(Description)。在每个用 @Test 注释的测试方法之前和之后调用它们。上面的扩展将在每次测试之前模拟 Dispatchers.Main 并在之后重置模拟。
之后，我只需要将我的扩展添加到我的测试文件中，如下所示：
@ExtendWith(InstantExecutorExtension::class, CoroutinesTestExtension::class)