测试LiveData有什么问题？测试没有通过

Question

我正在尝试使用LiveData测试ViewModel，但是存在一些问题。我无法得到它。我的测试只在一种情况下不通过 - HashMap的最后一个元素的值为true。但测试通过任何其他案件

这是我的测试没有通过

class PermissionsViewModelTest{
    @get:Rule
    var rule: TestRule = InstantTaskExecutorRule()
    lateinit var viewModel: PermissionsViewModel
    @Before
    fun setUp() {
        viewModel = PermissionsViewModel()
    }

   //Omited

   @Test
   fun `Should post false if permissions is not granted`() {
        val permissions = hashMapOf(
            Pair("123", true),
            Pair("123", false),
            Pair("123", true),
            Pair("123", true),
            Pair("123", true)
        )
        val observer = Mockito.mock(Observer::class.java) as Observer<Boolean>
        viewModel.isAllPermissionsGranted.observeForever(observer)
        viewModel.checkPermissions(permissions)
        assertFalse(viewModel.isAllPermissionsGranted.value!!)
    }
//Omitted
}

这是我的ViewModel

class PermissionsViewModel : ViewModel() {
        var isAllPermissionsGranted = MutableLiveData<Boolean>().apply {
            value = null
        }

        fun checkPermissions(permissionsResult: HashMap<String, Boolean>) {
            var isAllPermissionsGranted = true
            permissionsResult.values.forEach { isGranted ->
                if (!isGranted) {
                    isAllPermissionsGranted = false
                    return@forEach
                }
            }
            this.isAllPermissionsGranted.postValue(isAllPermissionsGranted)
        }
    }

我是否以错误的方式测试LiveData？或者测试LiveData有什么问题吗？

Answer 1

首先，我不确定您是否使用该hashmap进行测试，因为它具有相同的密钥，因此它可能会使用最后一对。其次，对于实时数据（因为它是异步的）我发现使用阻塞可观察扩展非常有帮助。这是阻塞可观察扩展的工作代码：

class PermissionsViewModelTest{
@get:Rule
var rule: TestRule = InstantTaskExecutorRule()
lateinit var viewModel: PermissionsViewModel
@Before
fun setUp() {
    viewModel = PermissionsViewModel()
}

//Omited

@Test
fun `Should post false if permissions is not granted`() {
    val permissions = hashMapOf(
            Pair("123", true),
            Pair("124", true),
            Pair("125", false),
            Pair("126", true),
            Pair("127", true)
    )
    val grantedObserver = viewModel.isAllPermissionsGranted
    viewModel.checkPermissions(permissions)
    val value = grantedObserver.blockingObserve() // extension below
    assertFalse(value!!)
    }

//Omited
}

class PermissionsViewModel : ViewModel() {
var isAllPermissionsGranted = MutableLiveData<Boolean>().apply {
    value = null
}

fun checkPermissions(permissionsResult: HashMap<String, Boolean>) {
    val isAllPermissionsGranted = permissionsResult.values.all{it}
    this.isAllPermissionsGranted.postValue(isAllPermissionsGranted)
    }
}

// blocking observe extension:
    fun <T> LiveData<T>.blockingObserve(): T? {
    var value: T? = null
    val latch = CountDownLatch(1)
        val innerObserver = Observer<T> {
        value = it
        latch.countDown()
    }
    observeForever(innerObserver)
    latch.await(2, TimeUnit.SECONDS)
    return value
}