使用 statIn 和 MVVM 的测试流程不更新数据

Question

你好吗 我使用扩展 fun 将流程转换为 StateIn 我应用了官方文档中的这些步骤 https://developer.android.com/kotlin/flow/test#statein

这是我的代码

@HiltViewModel
class HomeViewModel @Inject constructor(
    private val chatRepository: ChatRepository,
    private val messageRepository: MessageRepository,
    private val dispatchers :DispatcherProvider
) : ViewModel() {
    val homeState = chatRepository.getChats().map {
        HomeChatState(it)
    }.stateIn(viewModelScope, SharingStarted.WhileSubscribed(5000), HomeChatState())

    fun addTestChat(chat: Chat) {
        viewModelScope.launch(dispatchers.io) {
            chatRepository.insertChat(
                chat
            )
        }
    }

和这个假回购

class FakeChatRepo:ChatRepository {
    private val chats = MutableStateFlow<List<Chat>>(emptyList())
    override fun getChats(): Flow<List<Chat>> {
        return chats.asStateFlow()
    }

    override suspend fun insertChat(chat: Chat) {
        chats.emit(chats.value + chat)
    }

    override suspend fun deleteChatById(chat: Chat) {
        chats.value -= chat
    }

    override suspend fun readMessages(chatId: Int) {
        TODO("Not yet implemented")
    }
}

和这个测试代码

class ExampleUnitTest {
    private lateinit var homeViewModel: HomeViewModel

    @Before
    fun setup() {
        val messageRepo = MessageFakeRepository()
        val chatRepo = FakeChatRepo()
        val testDispatcher = TestDispatcherProvider()
        homeViewModel = HomeViewModel(chatRepo, messageRepo, testDispatcher)
    }

    @OptIn(ExperimentalCoroutinesApi::class)
    @Test
    fun addChat_returnTrue() = runTest {
        val chat =
            Chat(
                1,
                "sender test",
                "test",
                "salman",
                "Hi",
                "",
                LocalDateTime.now(),
                1,
                "hi"
            )
        val s = homeViewModel.homeState

        backgroundScope.launch(UnconfinedTestDispatcher(testScheduler)) {
            s.collect()
        }
        Truth.assertThat(s.value.chats).isEmpty()
        homeViewModel.addTestChat(chat) // here is issue not update data and always retrun empty valye
        Truth.assertThat(s.value.chats).containsExactly(chat)

    }
}

问题是当从 addTestChat() 添加数据时，它不起作用，除了 谢谢