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Commit 4241d874 authored by Alejandro Nijamkin's avatar Alejandro Nijamkin
Browse files

SysUiViewModel.hydratedStateOf 

Adds hydratedStateOf - a utility to help developers define a "hydrated"
(kept up-to-date) snapshot state (AKA compose State) property with a
single line of code and without needing to add a collector in the
activation code.

Bug: 354269846
Test: unit tests added
Test: manually verified with the next CL
Flag: NONE unused utility (in this CL)
Change-Id: Ibe0ccc623253d6df76cdef5c0842dda381b5a48a
parent 465342be

packages/SystemUI/Android.bp

+2 −0
Original line number Diff line number Diff line
@@ -893,6 +893,7 @@ android_robolectric_test { 
    ],

    static_libs: [

        "RoboTestLibraries",

        "androidx.compose.runtime_runtime",

    ],

    libs: [

        "android.test.runner",
@@ -929,6 +930,7 @@ android_robolectric_test { 
    ],

    static_libs: [

        "RoboTestLibraries",

        "androidx.compose.runtime_runtime",

    ],

    libs: [

        "android.test.runner",

packages/SystemUI/multivalentTests/src/com/android/systemui/lifecycle/SysUiViewModelTest.kt

+50 −0
Original line number Diff line number Diff line
@@ -17,8 +17,14 @@ 
package com.android.systemui.lifecycle



import android.view.View

import androidx.compose.foundation.layout.Column

import androidx.compose.material3.Text

import androidx.compose.runtime.getValue

import androidx.compose.runtime.mutableStateOf

import androidx.compose.ui.Modifier

import androidx.compose.ui.platform.testTag

import androidx.compose.ui.test.assertTextEquals

import androidx.compose.ui.test.hasTestTag

import androidx.compose.ui.test.junit4.createComposeRule

import androidx.test.ext.junit.runners.AndroidJUnit4

import androidx.test.filters.SmallTest
@@ -26,6 +32,8 @@ import com.android.systemui.SysuiTestCase 
import com.android.systemui.util.Assert

import com.google.common.truth.Truth.assertThat

import kotlinx.coroutines.awaitCancellation

import kotlinx.coroutines.flow.MutableStateFlow

import kotlinx.coroutines.flow.map

import kotlinx.coroutines.launch

import kotlinx.coroutines.test.runCurrent

import kotlinx.coroutines.test.runTest
@@ -149,6 +157,48 @@ class SysUiViewModelTest : SysuiTestCase() { 


        assertThat(viewModel.isActivated).isTrue()

    }



    @Test

    fun hydratedStateOf() {

        val keepAliveMutable = mutableStateOf(true)

        val upstreamStateFlow = MutableStateFlow(true)

        val upstreamFlow = upstreamStateFlow.map { !it }

        composeRule.setContent {

            val keepAlive by keepAliveMutable

            if (keepAlive) {

                val viewModel = rememberViewModel {

                    FakeSysUiViewModel(

                        upstreamFlow = upstreamFlow,

                        upstreamStateFlow = upstreamStateFlow,

                    )

                }



                Column {

                    Text(

                        "upstreamStateFlow=${viewModel.stateBackedByStateFlow}",

                        Modifier.testTag("upstreamStateFlow")

                    )

                    Text(

                        "upstreamFlow=${viewModel.stateBackedByFlow}",

                        Modifier.testTag("upstreamFlow")

                    )

                }

            }

        }



        composeRule.waitForIdle()

        composeRule

            .onNode(hasTestTag("upstreamStateFlow"))

            .assertTextEquals("upstreamStateFlow=true")

        composeRule.onNode(hasTestTag("upstreamFlow")).assertTextEquals("upstreamFlow=false")



        composeRule.runOnUiThread { upstreamStateFlow.value = false }

        composeRule.waitForIdle()

        composeRule

            .onNode(hasTestTag("upstreamStateFlow"))

            .assertTextEquals("upstreamStateFlow=false")

        composeRule.onNode(hasTestTag("upstreamFlow")).assertTextEquals("upstreamFlow=true")

    }

}



private class FakeViewModel : SysUiViewModel() {

packages/SystemUI/src/com/android/systemui/lifecycle/SysUiViewModel.kt

+32 −0
Original line number Diff line number Diff line
@@ -18,13 +18,45 @@ package com.android.systemui.lifecycle 


import android.view.View

import androidx.compose.runtime.Composable

import androidx.compose.runtime.State

import androidx.compose.runtime.mutableStateOf

import androidx.compose.runtime.snapshots.StateFactoryMarker

import kotlinx.coroutines.CoroutineScope

import kotlinx.coroutines.awaitCancellation

import kotlinx.coroutines.flow.Flow

import kotlinx.coroutines.flow.StateFlow

import kotlinx.coroutines.launch



/** Base class for all System UI view-models. */

abstract class SysUiViewModel : BaseActivatable() {



    @StateFactoryMarker

    fun <T> hydratedStateOf(

        source: StateFlow<T>,

    ): State<T> {

        return hydratedStateOf(

            initialValue = source.value,

            source = source,

        )

    }



    @StateFactoryMarker

    fun <T> hydratedStateOf(

        initialValue: T,

        source: Flow<T>,

    ): State<T> {

        val mutableState = mutableStateOf(initialValue)

        addChild(

            object : BaseActivatable() {

                override suspend fun onActivated(): Nothing {

                    source.collect { mutableState.value = it }

                    awaitCancellation()

                }

            }

        )

        return mutableState

    }



    override suspend fun onActivated(): Nothing {

        awaitCancellation()

    }

packages/SystemUI/tests/utils/src/com/android/systemui/lifecycle/FakeSysUiViewModel.kt

+12 −0
Original line number Diff line number Diff line
@@ -16,15 +16,27 @@ 


package com.android.systemui.lifecycle



import androidx.compose.runtime.getValue

import kotlinx.coroutines.awaitCancellation

import kotlinx.coroutines.flow.Flow

import kotlinx.coroutines.flow.MutableStateFlow

import kotlinx.coroutines.flow.StateFlow

import kotlinx.coroutines.flow.asStateFlow

import kotlinx.coroutines.flow.flowOf



class FakeSysUiViewModel(

    private val onActivation: () -> Unit = {},

    private val onDeactivation: () -> Unit = {},

    private val upstreamFlow: Flow<Boolean> = flowOf(true),

    private val upstreamStateFlow: StateFlow<Boolean> = MutableStateFlow(true).asStateFlow(),

) : SysUiViewModel() {



    var activationCount = 0

    var cancellationCount = 0



    val stateBackedByFlow: Boolean by hydratedStateOf(initialValue = true, source = upstreamFlow)

    val stateBackedByStateFlow: Boolean by hydratedStateOf(source = upstreamStateFlow)



    override suspend fun onActivated(): Nothing {

        activationCount++

        onActivation()