Show a Stopwatch widget in communal blueprint

This change introduces a keyguard section for widgets in communal mode,
and adds a Stopwatch widget to it, laid out at the bottom right corner.

Bug: 288275889
Test: adb shell cmd statusbar flag widget_on_keyguard on && \
      adb shell setprop ctl.restart zygote && \
      adb shell cmd statusbar blueprint communal
Test: atest KeyguardWidgetRepositoryImplTest
Test: atest CommunalInteractorTest
Test: atest DefaultCommunalBlueprintTest

Change-Id: Ib8a5a18bd78778c0915ef1796c594e170f2a0b64

19 files changed, 988 insertions, 8 deletions

diff --git a/packages/SystemUI/res/values/ids.xml b/packages/SystemUI/res/values/ids.xml
index d2cb475ad2b0..4e72518bc613 100644
--- a/packages/SystemUI/res/values/ids.xml
+++ b/packages/SystemUI/res/values/ids.xml
@@ -219,4 +219,7 @@
     <!-- Privacy dialog -->
     <item type="id" name="privacy_dialog_close_app_button" />
     <item type="id" name="privacy_dialog_manage_app_button" />
+
+    <!-- Communal mode -->
+    <item type="id" name="communal_widget_wrapper" />
 </resources>
diff --git a/packages/SystemUI/src/com/android/systemui/communal/data/repository/CommunalWidgetRepository.kt b/packages/SystemUI/src/com/android/systemui/communal/data/repository/CommunalWidgetRepository.kt
new file mode 100644
index 000000000000..e2a7d077a32c
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/data/repository/CommunalWidgetRepository.kt
@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.communal.data.repository
+
+import android.appwidget.AppWidgetHost
+import android.appwidget.AppWidgetManager
+import android.appwidget.AppWidgetProviderInfo
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.IntentFilter
+import android.content.pm.PackageManager
+import android.os.UserManager
+import com.android.systemui.broadcast.BroadcastDispatcher
+import com.android.systemui.common.coroutine.ChannelExt.trySendWithFailureLogging
+import com.android.systemui.communal.shared.CommunalAppWidgetInfo
+import com.android.systemui.dagger.SysUISingleton
+import com.android.systemui.flags.FeatureFlags
+import com.android.systemui.flags.Flags
+import com.android.systemui.log.LogBuffer
+import com.android.systemui.log.core.Logger
+import com.android.systemui.log.dagger.CommunalLog
+import com.android.systemui.settings.UserTracker
+import javax.inject.Inject
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.map
+
+/** Encapsulates the state of widgets for communal mode. */
+interface CommunalWidgetRepository {
+    /** A flow of provider info for the stopwatch widget, or null if widget is unavailable. */
+    val stopwatchAppWidgetInfo: Flow<CommunalAppWidgetInfo?>
+}
+
+@SysUISingleton
+class CommunalWidgetRepositoryImpl
+@Inject
+constructor(
+    private val appWidgetManager: AppWidgetManager,
+    private val appWidgetHost: AppWidgetHost,
+    broadcastDispatcher: BroadcastDispatcher,
+    private val packageManager: PackageManager,
+    private val userManager: UserManager,
+    private val userTracker: UserTracker,
+    @CommunalLog logBuffer: LogBuffer,
+    featureFlags: FeatureFlags,
+) : CommunalWidgetRepository {
+    companion object {
+        const val TAG = "CommunalWidgetRepository"
+        const val WIDGET_LABEL = "Stopwatch"
+    }
+
+    private val logger = Logger(logBuffer, TAG)
+
+    // Whether the [AppWidgetHost] is listening for updates.
+    private var isHostListening = false
+
+    // Widgets that should be rendered in communal mode.
+    private val widgets: HashMap<Int, CommunalAppWidgetInfo> = hashMapOf()
+
+    private val isUserUnlocked: Flow<Boolean> = callbackFlow {
+        if (!featureFlags.isEnabled(Flags.WIDGET_ON_KEYGUARD)) {
+            awaitClose()
+        }
+
+        fun isUserUnlockingOrUnlocked(): Boolean {
+            return userManager.isUserUnlockingOrUnlocked(userTracker.userHandle)
+        }
+
+        fun send() {
+            trySendWithFailureLogging(isUserUnlockingOrUnlocked(), TAG)
+        }
+
+        if (isUserUnlockingOrUnlocked()) {
+            send()
+            awaitClose()
+        } else {
+            val receiver =
+                object : BroadcastReceiver() {
+                    override fun onReceive(context: Context?, intent: Intent?) {
+                        send()
+                    }
+                }
+
+            broadcastDispatcher.registerReceiver(
+                receiver,
+                IntentFilter(Intent.ACTION_USER_UNLOCKED),
+            )
+
+            awaitClose { broadcastDispatcher.unregisterReceiver(receiver) }
+        }
+    }
+
+    override val stopwatchAppWidgetInfo: Flow<CommunalAppWidgetInfo?> =
+        isUserUnlocked.map { isUserUnlocked ->
+            if (!isUserUnlocked) {
+                clearWidgets()
+                stopListening()
+                return@map null
+            }
+
+            startListening()
+
+            val providerInfo =
+                appWidgetManager.installedProviders.find {
+                    it.loadLabel(packageManager).equals(WIDGET_LABEL)
+                }
+
+            if (providerInfo == null) {
+                logger.w("Cannot find app widget: $WIDGET_LABEL")
+                return@map null
+            }
+
+            return@map addWidget(providerInfo)
+        }
+
+    private fun startListening() {
+        if (isHostListening) {
+            return
+        }
+
+        appWidgetHost.startListening()
+        isHostListening = true
+    }
+
+    private fun stopListening() {
+        if (!isHostListening) {
+            return
+        }
+
+        appWidgetHost.stopListening()
+        isHostListening = false
+    }
+
+    private fun addWidget(providerInfo: AppWidgetProviderInfo): CommunalAppWidgetInfo {
+        val existing = widgets.values.firstOrNull { it.providerInfo == providerInfo }
+        if (existing != null) {
+            return existing
+        }
+
+        val appWidgetId = appWidgetHost.allocateAppWidgetId()
+        val widget =
+            CommunalAppWidgetInfo(
+                providerInfo,
+                appWidgetId,
+            )
+        widgets[appWidgetId] = widget
+        return widget
+    }
+
+    private fun clearWidgets() {
+        widgets.keys.forEach { appWidgetId -> appWidgetHost.deleteAppWidgetId(appWidgetId) }
+        widgets.clear()
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/data/repository/CommunalWidgetRepositoryModule.kt b/packages/SystemUI/src/com/android/systemui/communal/data/repository/CommunalWidgetRepositoryModule.kt
new file mode 100644
index 000000000000..3d1185b79275
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/data/repository/CommunalWidgetRepositoryModule.kt
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package com.android.systemui.communal.data.repository
+
+import android.appwidget.AppWidgetHost
+import android.appwidget.AppWidgetManager
+import android.content.Context
+import com.android.systemui.dagger.SysUISingleton
+import com.android.systemui.dagger.qualifiers.Application
+import dagger.Binds
+import dagger.Module
+import dagger.Provides
+
+@Module
+interface CommunalWidgetRepositoryModule {
+    companion object {
+        private const val APP_WIDGET_HOST_ID = 116
+
+        @SysUISingleton
+        @Provides
+        fun provideAppWidgetManager(@Application context: Context): AppWidgetManager {
+            return AppWidgetManager.getInstance(context)
+        }
+
+        @SysUISingleton
+        @Provides
+        fun provideAppWidgetHost(@Application context: Context): AppWidgetHost {
+            return AppWidgetHost(context, APP_WIDGET_HOST_ID)
+        }
+    }
+
+    @Binds
+    fun communalWidgetRepository(impl: CommunalWidgetRepositoryImpl): CommunalWidgetRepository
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/domain/interactor/CommunalInteractor.kt b/packages/SystemUI/src/com/android/systemui/communal/domain/interactor/CommunalInteractor.kt
new file mode 100644
index 000000000000..6dc305e6f826
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/domain/interactor/CommunalInteractor.kt
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.communal.domain.interactor
+
+import com.android.systemui.communal.data.repository.CommunalWidgetRepository
+import com.android.systemui.communal.shared.CommunalAppWidgetInfo
+import com.android.systemui.dagger.SysUISingleton
+import javax.inject.Inject
+import kotlinx.coroutines.flow.Flow
+
+/** Encapsulates business-logic related to communal mode. */
+@SysUISingleton
+class CommunalInteractor
+@Inject
+constructor(
+    widgetRepository: CommunalWidgetRepository,
+) {
+    /** A flow of info about the widget to be displayed, or null if widget is unavailable. */
+    val appWidgetInfo: Flow<CommunalAppWidgetInfo?> = widgetRepository.stopwatchAppWidgetInfo
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/shared/CommunalAppWidgetInfo.kt b/packages/SystemUI/src/com/android/systemui/communal/shared/CommunalAppWidgetInfo.kt
new file mode 100644
index 000000000000..0803a01b93b8
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/shared/CommunalAppWidgetInfo.kt
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package com.android.systemui.communal.shared
+
+import android.appwidget.AppWidgetProviderInfo
+
+/** A data class that stores info about an app widget that displays in communal mode. */
+data class CommunalAppWidgetInfo(
+    val providerInfo: AppWidgetProviderInfo,
+    val appWidgetId: Int,
+)
diff --git a/packages/SystemUI/src/com/android/systemui/communal/ui/adapter/CommunalWidgetViewAdapter.kt b/packages/SystemUI/src/com/android/systemui/communal/ui/adapter/CommunalWidgetViewAdapter.kt
new file mode 100644
index 000000000000..2a08d7f6bc28
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/ui/adapter/CommunalWidgetViewAdapter.kt
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.communal.ui.adapter
+
+import android.appwidget.AppWidgetHost
+import android.appwidget.AppWidgetManager
+import android.content.Context
+import android.util.SizeF
+import com.android.systemui.communal.shared.CommunalAppWidgetInfo
+import com.android.systemui.communal.ui.view.CommunalWidgetWrapper
+import com.android.systemui.dagger.qualifiers.Application
+import com.android.systemui.log.LogBuffer
+import com.android.systemui.log.core.Logger
+import com.android.systemui.log.dagger.CommunalLog
+import javax.inject.Inject
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+
+/** Transforms a [CommunalAppWidgetInfo] to a view that renders the widget. */
+class CommunalWidgetViewAdapter
+@Inject
+constructor(
+    @Application private val context: Context,
+    private val appWidgetManager: AppWidgetManager,
+    private val appWidgetHost: AppWidgetHost,
+    @CommunalLog logBuffer: LogBuffer,
+) {
+    companion object {
+        private const val TAG = "CommunalWidgetViewAdapter"
+    }
+
+    private val logger = Logger(logBuffer, TAG)
+
+    fun adapt(providerInfoFlow: Flow<CommunalAppWidgetInfo?>): Flow<CommunalWidgetWrapper?> =
+        providerInfoFlow.map {
+            if (it == null) {
+                return@map null
+            }
+
+            val appWidgetId = it.appWidgetId
+            val providerInfo = it.providerInfo
+
+            if (appWidgetManager.bindAppWidgetIdIfAllowed(appWidgetId, providerInfo.provider)) {
+                logger.d("Success binding app widget id: $appWidgetId")
+                return@map CommunalWidgetWrapper(context).apply {
+                    addView(
+                        appWidgetHost.createView(context, appWidgetId, providerInfo).apply {
+                            // Set the widget to minimum width and height
+                            updateAppWidgetSize(
+                                appWidgetManager.getAppWidgetOptions(appWidgetId),
+                                listOf(
+                                    SizeF(
+                                        providerInfo.minResizeWidth.toFloat(),
+                                        providerInfo.minResizeHeight.toFloat()
+                                    )
+                                )
+                            )
+                        }
+                    )
+                }
+            } else {
+                logger.w("Failed binding app widget id")
+                return@map null
+            }
+        }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/ui/binder/CommunalWidgetViewBinder.kt b/packages/SystemUI/src/com/android/systemui/communal/ui/binder/CommunalWidgetViewBinder.kt
new file mode 100644
index 000000000000..1b6d3a8095f0
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/ui/binder/CommunalWidgetViewBinder.kt
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.communal.ui.binder
+
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.repeatOnLifecycle
+import com.android.systemui.R
+import com.android.systemui.communal.ui.adapter.CommunalWidgetViewAdapter
+import com.android.systemui.communal.ui.view.CommunalWidgetWrapper
+import com.android.systemui.communal.ui.viewmodel.CommunalWidgetViewModel
+import com.android.systemui.keyguard.domain.interactor.KeyguardBlueprintInteractor
+import com.android.systemui.keyguard.ui.view.KeyguardRootView
+import com.android.systemui.lifecycle.repeatWhenAttached
+import kotlinx.coroutines.launch
+
+/** Binds [CommunalWidgetViewModel] to the keyguard root view. */
+object CommunalWidgetViewBinder {
+
+    @JvmStatic
+    fun bind(
+        rootView: KeyguardRootView,
+        viewModel: CommunalWidgetViewModel,
+        adapter: CommunalWidgetViewAdapter,
+        keyguardBlueprintInteractor: KeyguardBlueprintInteractor,
+    ) {
+        rootView.repeatWhenAttached {
+            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                launch {
+                    adapter.adapt(viewModel.appWidgetInfo).collect {
+                        val oldView =
+                            rootView.findViewById<CommunalWidgetWrapper>(
+                                R.id.communal_widget_wrapper
+                            )
+                        var dirty = false
+
+                        if (oldView != null) {
+                            rootView.removeView(oldView)
+                            dirty = true
+                        }
+
+                        if (it != null) {
+                            rootView.addView(it)
+                            dirty = true
+                        }
+
+                        if (dirty) {
+                            keyguardBlueprintInteractor.refreshBlueprint()
+                        }
+                    }
+                }
+
+                launch { viewModel.alpha.collect { rootView.alpha = it } }
+            }
+        }
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/ui/view/CommunalWidgetWrapper.kt b/packages/SystemUI/src/com/android/systemui/communal/ui/view/CommunalWidgetWrapper.kt
new file mode 100644
index 000000000000..560f4fac048f
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/ui/view/CommunalWidgetWrapper.kt
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package com.android.systemui.communal.ui.view
+
+import android.content.Context
+import android.util.AttributeSet
+import android.widget.LinearLayout
+import com.android.systemui.R
+
+/** Wraps around a widget rendered in communal mode. */
+class CommunalWidgetWrapper(context: Context, attrs: AttributeSet? = null) :
+    LinearLayout(context, attrs) {
+    init {
+        id = R.id.communal_widget_wrapper
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprint.kt b/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprint.kt
index bf402749add7..c3369da68821 100644
--- a/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprint.kt
+++ b/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprint.kt
@@ -17,6 +17,7 @@
 package com.android.systemui.communal.ui.view.layout.blueprints
 
 import androidx.constraintlayout.widget.ConstraintSet
+import com.android.systemui.communal.ui.view.layout.sections.DefaultCommunalWidgetSection
 import com.android.systemui.dagger.SysUISingleton
 import com.android.systemui.keyguard.data.repository.KeyguardBlueprint
 import javax.inject.Inject
@@ -24,10 +25,16 @@ import javax.inject.Inject
 /** Blueprint for communal mode. */
 @SysUISingleton
 @JvmSuppressWildcards
-class DefaultCommunalBlueprint @Inject constructor() : KeyguardBlueprint {
+class DefaultCommunalBlueprint
+@Inject
+constructor(
+    private val defaultCommunalWidgetSection: DefaultCommunalWidgetSection,
+) : KeyguardBlueprint {
     override val id: String = COMMUNAL
 
-    override fun apply(constraintSet: ConstraintSet) {}
+    override fun apply(constraintSet: ConstraintSet) {
+        defaultCommunalWidgetSection.apply(constraintSet)
+    }
 
     companion object {
         const val COMMUNAL = "communal"
diff --git a/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/sections/DefaultCommunalWidgetSection.kt b/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/sections/DefaultCommunalWidgetSection.kt
new file mode 100644
index 000000000000..b0e3132a1fc7
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/ui/view/layout/sections/DefaultCommunalWidgetSection.kt
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.communal.ui.view.layout.sections
+
+import android.view.ViewGroup.LayoutParams.WRAP_CONTENT
+import androidx.constraintlayout.widget.ConstraintSet
+import androidx.constraintlayout.widget.ConstraintSet.BOTTOM
+import androidx.constraintlayout.widget.ConstraintSet.END
+import androidx.constraintlayout.widget.ConstraintSet.PARENT_ID
+import com.android.systemui.R
+import com.android.systemui.keyguard.data.repository.KeyguardSection
+import javax.inject.Inject
+
+class DefaultCommunalWidgetSection @Inject constructor() : KeyguardSection {
+    private val widgetAreaViewId = R.id.communal_widget_wrapper
+
+    override fun apply(constraintSet: ConstraintSet) {
+        constraintSet.apply {
+            constrainWidth(widgetAreaViewId, WRAP_CONTENT)
+            constrainHeight(widgetAreaViewId, WRAP_CONTENT)
+            connect(widgetAreaViewId, BOTTOM, PARENT_ID, BOTTOM)
+            connect(widgetAreaViewId, END, PARENT_ID, END)
+        }
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/communal/ui/viewmodel/CommunalWidgetViewModel.kt b/packages/SystemUI/src/com/android/systemui/communal/ui/viewmodel/CommunalWidgetViewModel.kt
new file mode 100644
index 000000000000..8fba342c49be
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/communal/ui/viewmodel/CommunalWidgetViewModel.kt
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.communal.ui.viewmodel
+
+import com.android.systemui.communal.domain.interactor.CommunalInteractor
+import com.android.systemui.communal.shared.CommunalAppWidgetInfo
+import com.android.systemui.dagger.SysUISingleton
+import com.android.systemui.keyguard.ui.viewmodel.KeyguardBottomAreaViewModel
+import javax.inject.Inject
+import kotlinx.coroutines.flow.Flow
+
+@SysUISingleton
+class CommunalWidgetViewModel
+@Inject
+constructor(
+    communalInteractor: CommunalInteractor,
+    keyguardBottomAreaViewModel: KeyguardBottomAreaViewModel,
+) {
+    /** An observable for the alpha level for the communal widget area. */
+    val alpha: Flow<Float> = keyguardBottomAreaViewModel.alpha
+
+    /** A flow of info about the widget to be displayed, or null if widget is unavailable. */
+    val appWidgetInfo: Flow<CommunalAppWidgetInfo?> = communalInteractor.appWidgetInfo
+}
diff --git a/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewConfigurator.kt b/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewConfigurator.kt
index 8e323d8140d5..9b323ee9a3f3 100644
--- a/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewConfigurator.kt
+++ b/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewConfigurator.kt
@@ -24,9 +24,13 @@ import com.android.keyguard.KeyguardStatusViewController
 import com.android.keyguard.dagger.KeyguardStatusViewComponent
 import com.android.systemui.CoreStartable
 import com.android.systemui.R
+import com.android.systemui.communal.ui.adapter.CommunalWidgetViewAdapter
+import com.android.systemui.communal.ui.binder.CommunalWidgetViewBinder
+import com.android.systemui.communal.ui.viewmodel.CommunalWidgetViewModel
 import com.android.systemui.dagger.SysUISingleton
 import com.android.systemui.flags.FeatureFlags
 import com.android.systemui.flags.Flags
+import com.android.systemui.keyguard.domain.interactor.KeyguardBlueprintInteractor
 import com.android.systemui.keyguard.ui.binder.KeyguardAmbientIndicationAreaViewBinder
 import com.android.systemui.keyguard.ui.binder.KeyguardBlueprintViewBinder
 import com.android.systemui.keyguard.ui.binder.KeyguardIndicationAreaBinder
@@ -83,6 +87,9 @@ constructor(
     private val keyguardBlueprintCommandListener: KeyguardBlueprintCommandListener,
     private val keyguardBlueprintViewModel: KeyguardBlueprintViewModel,
     private val keyguardStatusViewComponentFactory: KeyguardStatusViewComponent.Factory,
+    private val keyguardBlueprintInteractor: KeyguardBlueprintInteractor,
+    private val communalWidgetViewModel: CommunalWidgetViewModel,
+    private val communalWidgetViewAdapter: CommunalWidgetViewAdapter,
 ) : CoreStartable {
 
     private var rootViewHandle: DisposableHandle? = null
@@ -106,6 +113,7 @@ constructor(
         bindRightShortcut()
         bindAmbientIndicationArea()
         bindSettingsPopupMenu()
+        bindCommunalWidgetArea()
 
         KeyguardBlueprintViewBinder.bind(keyguardRootView, keyguardBlueprintViewModel)
         keyguardBlueprintCommandListener.start()
@@ -279,6 +287,19 @@ constructor(
         }
     }
 
+    private fun bindCommunalWidgetArea() {
+        if (!featureFlags.isEnabled(Flags.WIDGET_ON_KEYGUARD)) {
+            return
+        }
+
+        CommunalWidgetViewBinder.bind(
+            keyguardRootView,
+            communalWidgetViewModel,
+            communalWidgetViewAdapter,
+            keyguardBlueprintInteractor,
+        )
+    }
+
     /**
      * Temporary, to allow NotificationPanelViewController to use the same instance while code is
      * migrated: b/288242803
diff --git a/packages/SystemUI/src/com/android/systemui/keyguard/dagger/KeyguardModule.java b/packages/SystemUI/src/com/android/systemui/keyguard/dagger/KeyguardModule.java
index 9a44230cf185..13dfe24e7e19 100644
--- a/packages/SystemUI/src/com/android/systemui/keyguard/dagger/KeyguardModule.java
+++ b/packages/SystemUI/src/com/android/systemui/keyguard/dagger/KeyguardModule.java
@@ -37,6 +37,7 @@ import com.android.systemui.animation.ActivityLaunchAnimator;
 import com.android.systemui.broadcast.BroadcastDispatcher;
 import com.android.systemui.classifier.FalsingCollector;
 import com.android.systemui.classifier.FalsingModule;
+import com.android.systemui.communal.data.repository.CommunalWidgetRepositoryModule;
 import com.android.systemui.dagger.SysUISingleton;
 import com.android.systemui.dagger.qualifiers.Main;
 import com.android.systemui.dagger.qualifiers.UiBackground;
@@ -75,11 +76,12 @@ import com.android.systemui.util.time.SystemClock;
 import com.android.systemui.wallpapers.data.repository.WallpaperRepository;
 import com.android.wm.shell.keyguard.KeyguardTransitions;
 
-import java.util.concurrent.Executor;
-
 import dagger.Lazy;
 import dagger.Module;
 import dagger.Provides;
+
+import java.util.concurrent.Executor;
+
 import kotlinx.coroutines.CoroutineDispatcher;
 
 /**
@@ -91,6 +93,7 @@ import kotlinx.coroutines.CoroutineDispatcher;
         KeyguardStatusViewComponent.class,
         KeyguardUserSwitcherComponent.class},
         includes = {
+            CommunalWidgetRepositoryModule.class,
             FalsingModule.class,
             KeyguardDataQuickAffordanceModule.class,
             KeyguardRepositoryModule.class,
diff --git a/packages/SystemUI/src/com/android/systemui/log/dagger/CommunalLog.kt b/packages/SystemUI/src/com/android/systemui/log/dagger/CommunalLog.kt
new file mode 100644
index 000000000000..afb18f1f23c4
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/log/dagger/CommunalLog.kt
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.log.dagger
+
+import javax.inject.Qualifier
+
+/** A [com.android.systemui.log.LogBuffer] for communal-related logging. */
+@Qualifier @MustBeDocumented @Retention(AnnotationRetention.RUNTIME) annotation class CommunalLog
diff --git a/packages/SystemUI/src/com/android/systemui/log/dagger/LogModule.java b/packages/SystemUI/src/com/android/systemui/log/dagger/LogModule.java
index cc1504a1df97..cbb29cd9ea63 100644
--- a/packages/SystemUI/src/com/android/systemui/log/dagger/LogModule.java
+++ b/packages/SystemUI/src/com/android/systemui/log/dagger/LogModule.java
@@ -489,6 +489,16 @@ public class LogModule {
         return factory.create("DreamLog", 250);
     }
 
+    /**
+     * Provides a {@link LogBuffer} for communal-related logs.
+     */
+    @Provides
+    @SysUISingleton
+    @CommunalLog
+    public static LogBuffer provideCommunalLogBuffer(LogBufferFactory factory) {
+        return factory.create("CommunalLog", 250);
+    }
+
     /** Provides a {@link LogBuffer} for display metrics related logs. */
     @Provides
     @SysUISingleton
diff --git a/packages/SystemUI/tests/src/com/android/systemui/communal/data/repository/CommunalWidgetRepositoryImplTest.kt b/packages/SystemUI/tests/src/com/android/systemui/communal/data/repository/CommunalWidgetRepositoryImplTest.kt
new file mode 100644
index 000000000000..3df9cbb29e4a
--- /dev/null
+++ b/packages/SystemUI/tests/src/com/android/systemui/communal/data/repository/CommunalWidgetRepositoryImplTest.kt
@@ -0,0 +1,285 @@
+package com.android.systemui.communal.data.repository
+
+import android.appwidget.AppWidgetHost
+import android.appwidget.AppWidgetManager
+import android.appwidget.AppWidgetProviderInfo
+import android.content.BroadcastReceiver
+import android.content.pm.PackageManager
+import android.os.UserHandle
+import android.os.UserManager
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.SmallTest
+import com.android.systemui.SysuiTestCase
+import com.android.systemui.broadcast.BroadcastDispatcher
+import com.android.systemui.coroutines.collectLastValue
+import com.android.systemui.flags.FeatureFlags
+import com.android.systemui.flags.Flags
+import com.android.systemui.log.LogBuffer
+import com.android.systemui.log.core.FakeLogBuffer
+import com.android.systemui.settings.UserTracker
+import com.android.systemui.util.mockito.any
+import com.android.systemui.util.mockito.kotlinArgumentCaptor
+import com.android.systemui.util.mockito.nullable
+import com.android.systemui.util.mockito.whenever
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.Mockito
+import org.mockito.Mockito.anyInt
+import org.mockito.MockitoAnnotations
+
+@OptIn(ExperimentalCoroutinesApi::class)
+@SmallTest
+@RunWith(AndroidJUnit4::class)
+class CommunalWidgetRepositoryImplTest : SysuiTestCase() {
+    @Mock private lateinit var appWidgetManager: AppWidgetManager
+
+    @Mock private lateinit var appWidgetHost: AppWidgetHost
+
+    @Mock private lateinit var broadcastDispatcher: BroadcastDispatcher
+
+    @Mock private lateinit var packageManager: PackageManager
+
+    @Mock private lateinit var userManager: UserManager
+
+    @Mock private lateinit var userHandle: UserHandle
+
+    @Mock private lateinit var userTracker: UserTracker
+
+    @Mock private lateinit var featureFlags: FeatureFlags
+
+    @Mock private lateinit var stopwatchProviderInfo: AppWidgetProviderInfo
+
+    private lateinit var logBuffer: LogBuffer
+
+    private val testDispatcher = StandardTestDispatcher()
+    private val testScope = TestScope(testDispatcher)
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+
+        logBuffer = FakeLogBuffer.Factory.create()
+
+        featureFlagEnabled(true)
+        whenever(stopwatchProviderInfo.loadLabel(any())).thenReturn("Stopwatch")
+        whenever(userTracker.userHandle).thenReturn(userHandle)
+    }
+
+    @Test
+    fun broadcastReceiver_featureDisabled_doNotRegisterUserUnlockedBroadcastReceiver() =
+        testScope.runTest {
+            featureFlagEnabled(false)
+            val repository = initCommunalWidgetRepository()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+            verifyBroadcastReceiverNeverRegistered()
+        }
+
+    @Test
+    fun broadcastReceiver_featureEnabledAndUserUnlocked_doNotRegisterBroadcastReceiver() =
+        testScope.runTest {
+            userUnlocked(true)
+            val repository = initCommunalWidgetRepository()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+            verifyBroadcastReceiverNeverRegistered()
+        }
+
+    @Test
+    fun broadcastReceiver_featureEnabledAndUserLocked_registerBroadcastReceiver() =
+        testScope.runTest {
+            userUnlocked(false)
+            val repository = initCommunalWidgetRepository()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+            verifyBroadcastReceiverRegistered()
+        }
+
+    @Test
+    fun broadcastReceiver_whenFlowFinishes_unregisterBroadcastReceiver() =
+        testScope.runTest {
+            userUnlocked(false)
+            val repository = initCommunalWidgetRepository()
+
+            val job = launch { repository.stopwatchAppWidgetInfo.collect() }
+            runCurrent()
+            val receiver = broadcastReceiverUpdate()
+
+            job.cancel()
+            runCurrent()
+
+            Mockito.verify(broadcastDispatcher).unregisterReceiver(receiver)
+        }
+
+    @Test
+    fun stopwatch_whenUserUnlocks_receiveProviderInfo() =
+        testScope.runTest {
+            userUnlocked(false)
+            val repository = initCommunalWidgetRepository()
+            val lastStopwatchProviderInfo = collectLastValue(repository.stopwatchAppWidgetInfo)
+            assertThat(lastStopwatchProviderInfo()).isNull()
+
+            userUnlocked(true)
+            installedProviders(listOf(stopwatchProviderInfo))
+            broadcastReceiverUpdate()
+
+            assertThat(lastStopwatchProviderInfo()?.providerInfo).isEqualTo(stopwatchProviderInfo)
+        }
+
+    @Test
+    fun stopwatch_userUnlockedButWidgetNotInstalled_noProviderInfo() =
+        testScope.runTest {
+            userUnlocked(true)
+            installedProviders(listOf())
+
+            val repository = initCommunalWidgetRepository()
+
+            val lastStopwatchProviderInfo = collectLastValue(repository.stopwatchAppWidgetInfo)
+            assertThat(lastStopwatchProviderInfo()).isNull()
+        }
+
+    @Test
+    fun appWidgetId_providerInfoAvailable_allocateAppWidgetId() =
+        testScope.runTest {
+            userUnlocked(true)
+            installedProviders(listOf(stopwatchProviderInfo))
+            val repository = initCommunalWidgetRepository()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+            Mockito.verify(appWidgetHost).allocateAppWidgetId()
+        }
+
+    @Test
+    fun appWidgetId_userLockedAgainAfterProviderInfoAvailable_deleteAppWidgetId() =
+        testScope.runTest {
+            whenever(appWidgetHost.allocateAppWidgetId()).thenReturn(123456)
+            userUnlocked(false)
+            val repository = initCommunalWidgetRepository()
+            val lastStopwatchProviderInfo = collectLastValue(repository.stopwatchAppWidgetInfo)
+            assertThat(lastStopwatchProviderInfo()).isNull()
+
+            // User unlocks
+            userUnlocked(true)
+            installedProviders(listOf(stopwatchProviderInfo))
+            broadcastReceiverUpdate()
+
+            // Verify app widget id allocated
+            assertThat(lastStopwatchProviderInfo()?.appWidgetId).isEqualTo(123456)
+            Mockito.verify(appWidgetHost).allocateAppWidgetId()
+            Mockito.verify(appWidgetHost, Mockito.never()).deleteAppWidgetId(anyInt())
+
+            // User locked again
+            userUnlocked(false)
+            broadcastReceiverUpdate()
+
+            // Verify app widget id deleted
+            assertThat(lastStopwatchProviderInfo()).isNull()
+            Mockito.verify(appWidgetHost).deleteAppWidgetId(123456)
+        }
+
+    @Test
+    fun appWidgetHost_userUnlocked_startListening() =
+        testScope.runTest {
+            userUnlocked(false)
+            val repository = initCommunalWidgetRepository()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+            Mockito.verify(appWidgetHost, Mockito.never()).startListening()
+
+            userUnlocked(true)
+            broadcastReceiverUpdate()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+
+            Mockito.verify(appWidgetHost).startListening()
+        }
+
+    @Test
+    fun appWidgetHost_userLockedAgain_stopListening() =
+        testScope.runTest {
+            userUnlocked(false)
+            val repository = initCommunalWidgetRepository()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+
+            userUnlocked(true)
+            broadcastReceiverUpdate()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+
+            Mockito.verify(appWidgetHost).startListening()
+            Mockito.verify(appWidgetHost, Mockito.never()).stopListening()
+
+            userUnlocked(false)
+            broadcastReceiverUpdate()
+            collectLastValue(repository.stopwatchAppWidgetInfo)()
+
+            Mockito.verify(appWidgetHost).stopListening()
+        }
+
+    private fun initCommunalWidgetRepository(): CommunalWidgetRepositoryImpl {
+        return CommunalWidgetRepositoryImpl(
+            appWidgetManager,
+            appWidgetHost,
+            broadcastDispatcher,
+            packageManager,
+            userManager,
+            userTracker,
+            logBuffer,
+            featureFlags,
+        )
+    }
+
+    private fun verifyBroadcastReceiverRegistered() {
+        Mockito.verify(broadcastDispatcher)
+            .registerReceiver(
+                any(),
+                any(),
+                nullable(),
+                nullable(),
+                anyInt(),
+                nullable(),
+            )
+    }
+
+    private fun verifyBroadcastReceiverNeverRegistered() {
+        Mockito.verify(broadcastDispatcher, Mockito.never())
+            .registerReceiver(
+                any(),
+                any(),
+                nullable(),
+                nullable(),
+                anyInt(),
+                nullable(),
+            )
+    }
+
+    private fun broadcastReceiverUpdate(): BroadcastReceiver {
+        val broadcastReceiverCaptor = kotlinArgumentCaptor<BroadcastReceiver>()
+        Mockito.verify(broadcastDispatcher)
+            .registerReceiver(
+                broadcastReceiverCaptor.capture(),
+                any(),
+                nullable(),
+                nullable(),
+                anyInt(),
+                nullable(),
+            )
+        broadcastReceiverCaptor.value.onReceive(null, null)
+        return broadcastReceiverCaptor.value
+    }
+
+    private fun featureFlagEnabled(enabled: Boolean) {
+        whenever(featureFlags.isEnabled(Flags.WIDGET_ON_KEYGUARD)).thenReturn(enabled)
+    }
+
+    private fun userUnlocked(userUnlocked: Boolean) {
+        whenever(userManager.isUserUnlockingOrUnlocked(userHandle)).thenReturn(userUnlocked)
+    }
+
+    private fun installedProviders(providers: List<AppWidgetProviderInfo>) {
+        whenever(appWidgetManager.installedProviders).thenReturn(providers)
+    }
+}
diff --git a/packages/SystemUI/tests/src/com/android/systemui/communal/domain/interactor/CommunalInteractorTest.kt b/packages/SystemUI/tests/src/com/android/systemui/communal/domain/interactor/CommunalInteractorTest.kt
new file mode 100644
index 000000000000..d28f530f04f3
--- /dev/null
+++ b/packages/SystemUI/tests/src/com/android/systemui/communal/domain/interactor/CommunalInteractorTest.kt
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package com.android.systemui.communal.domain.interactor
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.SmallTest
+import com.android.systemui.RoboPilotTest
+import com.android.systemui.SysuiTestCase
+import com.android.systemui.communal.data.repository.FakeCommunalWidgetRepository
+import com.android.systemui.communal.shared.CommunalAppWidgetInfo
+import com.android.systemui.coroutines.collectLastValue
+import com.google.common.truth.Truth.assertThat
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.runCurrent
+import kotlinx.coroutines.test.runTest
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.MockitoAnnotations
+
+@SmallTest
+@RoboPilotTest
+@OptIn(ExperimentalCoroutinesApi::class)
+@RunWith(AndroidJUnit4::class)
+class CommunalInteractorTest : SysuiTestCase() {
+    @Mock private lateinit var stopwatchAppWidgetInfo: CommunalAppWidgetInfo
+
+    private lateinit var testScope: TestScope
+
+    private lateinit var widgetRepository: FakeCommunalWidgetRepository
+    private lateinit var interactor: CommunalInteractor
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+
+        testScope = TestScope()
+        widgetRepository = FakeCommunalWidgetRepository()
+        interactor = CommunalInteractor(widgetRepository)
+    }
+
+    @Test
+    fun testAppWidgetInfoFlow() =
+        testScope.runTest {
+            val lastAppWidgetInfo = collectLastValue(interactor.appWidgetInfo)
+            runCurrent()
+            assertThat(lastAppWidgetInfo()).isNull()
+
+            widgetRepository.setStopwatchAppWidgetInfo(stopwatchAppWidgetInfo)
+            runCurrent()
+            assertThat(lastAppWidgetInfo()).isEqualTo(stopwatchAppWidgetInfo)
+        }
+}
diff --git a/packages/SystemUI/tests/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprintTest.kt b/packages/SystemUI/tests/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprintTest.kt
index 783bb47bb9b0..e3a75f161318 100644
--- a/packages/SystemUI/tests/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprintTest.kt
+++ b/packages/SystemUI/tests/src/com/android/systemui/communal/ui/view/layout/blueprints/DefaultCommunalBlueprintTest.kt
@@ -5,25 +5,32 @@ import android.testing.TestableLooper
 import androidx.constraintlayout.widget.ConstraintSet
 import androidx.test.filters.SmallTest
 import com.android.systemui.SysuiTestCase
+import com.android.systemui.communal.ui.view.layout.sections.DefaultCommunalWidgetSection
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.Mockito.verify
+import org.mockito.MockitoAnnotations
 
 @RunWith(AndroidTestingRunner::class)
 @TestableLooper.RunWithLooper(setAsMainLooper = true)
 @SmallTest
 class DefaultCommunalBlueprintTest : SysuiTestCase() {
+    @Mock private lateinit var widgetSection: DefaultCommunalWidgetSection
+
     private lateinit var blueprint: DefaultCommunalBlueprint
 
     @Before
     fun setup() {
-        blueprint = DefaultCommunalBlueprint()
+        MockitoAnnotations.initMocks(this)
+        blueprint = DefaultCommunalBlueprint(widgetSection)
     }
 
     @Test
-    fun apply_doesNothing() {
+    fun apply() {
         val cs = ConstraintSet()
         blueprint.apply(cs)
-        // Nothing happens yet.
+        verify(widgetSection).apply(cs)
     }
-}
\ No newline at end of file
+}
diff --git a/packages/SystemUI/tests/utils/src/com/android/systemui/communal/data/repository/FakeCommunalWidgetRepository.kt b/packages/SystemUI/tests/utils/src/com/android/systemui/communal/data/repository/FakeCommunalWidgetRepository.kt
new file mode 100644
index 000000000000..1a8c5830e453
--- /dev/null
+++ b/packages/SystemUI/tests/utils/src/com/android/systemui/communal/data/repository/FakeCommunalWidgetRepository.kt
@@ -0,0 +1,15 @@
+package com.android.systemui.communal.data.repository
+
+import com.android.systemui.communal.shared.CommunalAppWidgetInfo
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+
+/** Fake implementation of [CommunalWidgetRepository] */
+class FakeCommunalWidgetRepository : CommunalWidgetRepository {
+    private val _stopwatchAppWidgetInfo = MutableStateFlow<CommunalAppWidgetInfo?>(null)
+    override val stopwatchAppWidgetInfo: Flow<CommunalAppWidgetInfo?> = _stopwatchAppWidgetInfo
+
+    fun setStopwatchAppWidgetInfo(appWidgetInfo: CommunalAppWidgetInfo) {
+        _stopwatchAppWidgetInfo.value = appWidgetInfo
+    }
+}