我正在为视图模型编写单元测试，但运行测试时出现以下异常lateinit属性backendApi尚未初始化我想知道问题到底出在哪里

kotlin.UninitializedPropertyAccessException: lateinit property backendApi has not been initialized
        at com.chargeatfriends.android.ui.settings.register.SignInViewModelTest.getBackendApi(SignInViewModelTest.kt:24)
        at com.chargeatfriends.android.ui.settings.register.SignInViewModelTest.<init>(SignInViewModelTest.kt:26)
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
        at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:250)
        at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:260)
        at org.junit.runners.BlockJUnit4ClassRunner$2.runReflectiveCall(BlockJUnit4ClassRunner.java:309)
        at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
        at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:306)
        at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
        at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
        at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
        at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
        at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
        at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
        at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
        at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
        at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
        at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
        at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
        at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:110)
        at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
        at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:38)
        at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:62)
        at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
        at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
        at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
        at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
        at com.sun.proxy.$Proxy2.processTestClass(Unknown Source)
        at org.gradle.api.internal.tasks.testing.worker.TestWorker.processTestClass(TestWorker.java:121)
        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$1.run(ManagedExecutorImpl.java:48)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$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:829

）
在我的SignViewModelTest.kt下面

internal class SignInViewModelTest{
    private val _login =  MutableStateFlow<UiStateObject<RegisterResponse>>(UiStateObject.EMPTY)

         @Mock
        lateinit var backendApi:BackendApi

    val fakeAuthRepository = FakeAuthRepository(backendApi)
    val authRepository = AuthRepository(backendApi)
    @Before
    fun setUp() {

        MockitoAnnotations.initMocks(this)

    }
var login = _login

    @Test
    fun `testing repository`() = runBlockingTest {

        login.test {
            val fake = fakeAuthRepository.login("kyodgorbek@gmail.com", "12345678", "android", "123455")
            val real  = authRepository.login("kyodgorbek@gmail.com", "12345678", "android", "123455")
            assertEquals(fake,real)

        }
    }
}

我想知道我在哪里做错了，我已经在stackoverflow上遵循了所有可能的答案，它没有解决我的问题