Kotlin 合并状态流

我有一个问题，我一个人走不动. 在我的view Model中，有两个合并为一个流的StateFlow. 就像val mergedState = merge(state1, state2)个. 现在，当我更新state1时，mergedState的值也更改为state1的值. 但是，当我try 更新state2时，mergedState的值不会改变.

为了更好地演示，我编写了一个简单的示例:

这是一个视图模型

class FlowViewModel : ViewModel() {

    private val state1 = MutableStateFlow(0)
    private val state2 = MutableStateFlow(0)

    val mergedState = merge(state1, state2)

    fun updateState1(value: Int) {
        state1.value = value
    }

    fun updateState2(value: Int) {
        state2.value = value
    }
}

下面是测试它的代码

class ExampleUnitTest {

    private lateinit var flowViewModel: FlowViewModel

    @Before
    fun setUp() {
        Dispatchers.setMain(UnconfinedTestDispatcher())
        flowViewModel = FlowViewModel()
    }

    @After
    fun tearDown() {
        Dispatchers.resetMain()
    }

    @Test
    fun `test merged flow`() = runTest {
        assertThat(flowViewModel.mergedState.first()).isEqualTo(0)

        flowViewModel.updateState1(1)
        assertThat(flowViewModel.mergedState.first()).isEqualTo(1) //works as expected

        flowViewModel.updateState2(2)
        assertThat(flowViewModel.mergedState.first()).isEqualTo(2) //the value is still 1
    }
}

我也不管我先更新哪个州. 看起来只有更新了state1才会更新mergedState.

我很确定我在这里忽略了一些东西.