首先,您需要使用InstantTaskExecutorRule,这意味着:

@Rule public InstantTaskExecutorRule instantExecutorRule = new InstantTaskExecutorRule();

testCompile "android.arch.core:core-testing:$rootProject.ext.arch_version"

然后,您需要使用规则覆盖rxscheduler定义JUnit规则,或者在@Before内使用RxAndroidPlugins覆盖调度程序(如果您使用的是RxJava)

RxSchedulersOverrideRule:

public class RxSchedulersOverrideRule implements TestRule {
    @Override public Statement apply(final Statement base, Description description) {
    return new Statement() {
        @Override public void evaluate() throws Throwable {
            RxAndroidPlugins.reset();
            RxAndroidPlugins.setMainThreadSchedulerHandler(scheduler -> Schedulers.trampoline());

        RxJavaPlugins.reset();
        RxJavaPlugins.setIoSchedulerHandler(scheduler -> Schedulers.trampoline());
        RxJavaPlugins.setComputationSchedulerHandler(scheduler -> Schedulers.trampoline());
        RxJavaPlugins.setNewThreadSchedulerHandler(scheduler -> Schedulers.trampoline());

        base.evaluate();

        RxAndroidPlugins.reset();
        RxJavaPlugins.reset();
      }
    };
  }
}

@Rule public RxSchedulersOverrideRule rxSchedulersOverrideRule = new RxSchedulersOverrideRule();

另一个选项是在@Before中的setup()内调用:

RxAndroidPlugins.setInitMainThreadSchedulerHandler(schedulerCallable -> Schedulers.trampoline());

RxAndroidPlugins.reset(); 

确保观察者不在主线程上

Jeroen Mols implementation 对于JUnit 4和JUnit 5。我使用Junit 5方法,使用Kotlin、Junit 5、MockK和AssertJ库对Coinverse Open App的本地单元测试进行了测试。

JUnit 4

@卡洛斯·丹尼尔的 solution InstantExecutorRule 对于JUnit 4是正确的。

示例UnitTest。千吨

class ExampleUnitTest {

    @get:Rule
    val rule = InstantTaskExecutorRule()

    @Test
    fun `my test`() {
        val mutableLiveData = MutableLiveData<String>()
        mutableLiveData.postValue("test")
        assertEquals("test", mutableLiveData.value)
    }
}

建筑格拉德尔

dependencies {
    testImplementation 'android.arch.core:core-testing:X.X.X'
}

InstantExecutorExtension。千吨

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

class InstantExecutorExtension : BeforeEachCallback, AfterEachCallback {
    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
        })
    }

    override fun afterEach(context: ExtensionContext?) {
        ArchTaskExecutor.getInstance().setDelegate(null)
    }
}

这个 InstantExecutorExtension 在本地单元测试类中使用注释实现。

...
import androidx.paging.PagedList
import com.google.firebase.Timestamp
import io.mockk.*
import org.assertj.core.api.Assertions.assertThat
import org.junit.jupiter.api.AfterAll
import org.junit.jupiter.api.BeforeAll
import org.junit.jupiter.api.BeforeEach
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.extension.ExtendWith

@ExtendWith(InstantExecutorExtension::class)
class ContentViewModelTest {
    val timestamp = getTimeframe(DAY)

    @BeforeAll
    fun beforeAll() {
        mockkObject(ContentRepository)
    }

    @BeforeEach
    fun beforeEach() {
        clearAllMocks()
    }

    @AfterAll
    fun afterAll() {
        unmockkAll()
    }

    @Test
    fun `Feed Load`() {
        val content = Content("85", 0.0, Enums.ContentType.NONE, Timestamp.now(), "",
            "", "", "", "", "", "", MAIN,
            0, 0.0, 0.0, 0.0, 0.0,
            0.0, 0.0, 0.0, 0.0)
        every {
            getMainFeedList(any(), any())
        } returns MutableLiveData<Lce<ContentResult.PagedListResult>>().also { lce ->
            lce.value = Lce.Content(
                ContentResult.PagedListResult(
                    pagedList = MutableLiveData<PagedList<Content>>().apply {
                        this.value = listOf(content).asPagedList(
                            PagedList.Config.Builder().setEnablePlaceholders(false)
                                .setPrefetchDistance(24)
                                .setPageSize(12)
                                .build())
                        }, errorMessage = ""))
        }
        val contentViewModel = ContentViewModel(ContentRepository)
        contentViewModel.processEvent(ContentViewEvent.FeedLoad(MAIN, DAY, timestamp, false))
        assertThat(contentViewModel.feedViewState.getOrAwaitValue().contentList.getOrAwaitValue()[0])
            .isEqualTo(content)
        assertThat(contentViewModel.feedViewState.getOrAwaitValue().toolbar).isEqualTo(
            ToolbarState(
                    visibility = GONE,
                    titleRes = app_name,
                    isSupportActionBarEnabled = false))
        verify {
            getMainFeedList(any(), any())
        }
        confirmVerified(ContentRepository)
    }
}

@Carlos Daniel 的回答对我帮助很大,但面临另一个问题 Rule 未应用于 PowerMockRunner

@RunWith(PowerMockRunner::class)
@PowerMockRunnerDelegate(MockitoJUnitRunner::class) //this line allows you to use the powermock runner and mockito runner
@PrepareForTest(UnderTestClass::class)
class UnderTestClassTest {
@get:Rule
var instantExecutorRule = InstantTaskExecutorRule()

安德洛瓦

  implementation 'androidx.arch.core:core-testing:$version' 

 implementation 'android.arch.core:core-testing:$version'