Low battery notifications for USI styluses.

USI stylus low battery notifications should only appear when
bluetooth battery notifications are not available.

There is currently no way to differentiate USI styluses, so any
USI stylus being used will use the same notification.

Bug: 250908244
Test: StylusUsiPowerStartableTest StylusUsiPowerUiTest
Change-Id: I54cb59c1608c955f19db4776875e0dc3d9df1dd5

packages/SystemUI/res/values/strings.xml

@@ -2759,4 +2759,7 @@
     <string name="rear_display_accessibility_folded_animation">Foldable device being unfolded</string>
     <!-- Text for education page content description for unfolded animation. [CHAR_LIMIT=NONE] -->
     <string name="rear_display_accessibility_unfolded_animation">Foldable device being flipped around</string>
+
+    <!-- Title for notification of low stylus battery. [CHAR_LIMIT=NONE] -->
+    <string name="stylus_battery_low">Stylus battery low</string>
 </resources>

packages/SystemUI/src/com/android/systemui/dagger/FrameworkServicesModule.java

@@ -93,6 +93,8 @@ import android.view.accessibility.AccessibilityManager;
 import android.view.accessibility.CaptioningManager;
 import android.view.inputmethod.InputMethodManager;
 
+import androidx.core.app.NotificationManagerCompat;
+
 import com.android.internal.app.IBatteryStats;
 import com.android.internal.appwidget.IAppWidgetService;
 import com.android.internal.jank.InteractionJankMonitor;
@@ -389,6 +391,12 @@ public class FrameworkServicesModule {
         return context.getSystemService(NotificationManager.class);
     }
 
+    @Provides
+    @Singleton
+    static NotificationManagerCompat provideNotificationManagerCompat(Context context) {
+        return NotificationManagerCompat.from(context);
+    }
+
     /** */
     @Provides
     @Singleton

packages/SystemUI/src/com/android/systemui/dagger/SystemUICoreStartableModule.kt

@@ -42,6 +42,7 @@ import com.android.systemui.settings.dagger.MultiUserUtilsModule
 import com.android.systemui.shortcut.ShortcutKeyDispatcher
 import com.android.systemui.statusbar.notification.InstantAppNotifier
 import com.android.systemui.statusbar.phone.KeyguardLiftController
+import com.android.systemui.stylus.StylusUsiPowerStartable
 import com.android.systemui.temporarydisplay.chipbar.ChipbarCoordinator
 import com.android.systemui.theme.ThemeOverlayController
 import com.android.systemui.toast.ToastUI
@@ -251,4 +252,10 @@ abstract class SystemUICoreStartableModule {
     @IntoMap
     @ClassKey(RearDisplayDialogController::class)
     abstract fun bindRearDisplayDialogController(sysui: RearDisplayDialogController): CoreStartable
+
+    /** Inject into StylusUsiPowerStartable) */
+    @Binds
+    @IntoMap
+    @ClassKey(StylusUsiPowerStartable::class)
+    abstract fun bindStylusUsiPowerStartable(sysui: StylusUsiPowerStartable): CoreStartable
 }

packages/SystemUI/src/com/android/systemui/stylus/StylusUsiPowerStartable.kt

@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2022 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.stylus
+
+import android.hardware.BatteryState
+import android.hardware.input.InputManager
+import android.util.Log
+import android.view.InputDevice
+import com.android.systemui.CoreStartable
+import com.android.systemui.dagger.SysUISingleton
+import com.android.systemui.dagger.qualifiers.Background
+import com.android.systemui.flags.FeatureFlags
+import com.android.systemui.flags.Flags
+import java.util.concurrent.Executor
+import javax.inject.Inject
+
+/**
+ * A [CoreStartable] that listens to USI stylus battery events, to manage the [StylusUsiPowerUI]
+ * notification controller.
+ */
+@SysUISingleton
+class StylusUsiPowerStartable
+@Inject
+constructor(
+    private val stylusManager: StylusManager,
+    private val inputManager: InputManager,
+    private val stylusUsiPowerUi: StylusUsiPowerUI,
+    private val featureFlags: FeatureFlags,
+    @Background private val executor: Executor,
+) : CoreStartable, StylusManager.StylusCallback, InputManager.InputDeviceBatteryListener {
+
+    override fun onStylusAdded(deviceId: Int) {
+        val device = inputManager.getInputDevice(deviceId) ?: return
+
+        if (!device.isExternal) {
+            registerBatteryListener(deviceId)
+        }
+    }
+
+    override fun onStylusBluetoothConnected(deviceId: Int, btAddress: String) {
+        stylusUsiPowerUi.refresh()
+    }
+
+    override fun onStylusBluetoothDisconnected(deviceId: Int, btAddress: String) {
+        stylusUsiPowerUi.refresh()
+    }
+
+    override fun onStylusRemoved(deviceId: Int) {
+        val device = inputManager.getInputDevice(deviceId) ?: return
+
+        if (!device.isExternal) {
+            unregisterBatteryListener(deviceId)
+        }
+    }
+
+    override fun onBatteryStateChanged(
+        deviceId: Int,
+        eventTimeMillis: Long,
+        batteryState: BatteryState
+    ) {
+        if (batteryState.isPresent) {
+            stylusUsiPowerUi.updateBatteryState(batteryState)
+        }
+    }
+
+    private fun registerBatteryListener(deviceId: Int) {
+        try {
+            inputManager.addInputDeviceBatteryListener(deviceId, executor, this)
+        } catch (e: SecurityException) {
+            Log.e(TAG, "$e: Failed to register battery listener for $deviceId.")
+        }
+    }
+
+    private fun unregisterBatteryListener(deviceId: Int) {
+        try {
+            inputManager.removeInputDeviceBatteryListener(deviceId, this)
+        } catch (e: SecurityException) {
+            Log.e(TAG, "$e: Failed to unregister battery listener for $deviceId.")
+        }
+    }
+
+    override fun start() {
+        if (!featureFlags.isEnabled(Flags.ENABLE_USI_BATTERY_NOTIFICATIONS)) return
+        addBatteryListenerForInternalStyluses()
+
+        stylusManager.registerCallback(this)
+        stylusManager.startListener()
+    }
+
+    private fun addBatteryListenerForInternalStyluses() {
+        // For most devices, an active stylus is represented by an internal InputDevice.
+        // This InputDevice will be present in InputManager before CoreStartables run,
+        // and will not be removed. In many cases, it reports the battery level of the stylus.
+        inputManager.inputDeviceIds
+            .asSequence()
+            .mapNotNull { inputManager.getInputDevice(it) }
+            .filter { it.supportsSource(InputDevice.SOURCE_STYLUS) }
+            .forEach { onStylusAdded(it.id) }
+    }
+
+    companion object {
+        private val TAG = StylusUsiPowerStartable::class.simpleName.orEmpty()
+    }
+}

packages/SystemUI/src/com/android/systemui/stylus/StylusUsiPowerUI.kt

@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2022 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.stylus
+
+import android.Manifest
+import android.app.PendingIntent
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.IntentFilter
+import android.hardware.BatteryState
+import android.hardware.input.InputManager
+import android.os.Handler
+import android.os.UserHandle
+import android.view.InputDevice
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationManagerCompat
+import com.android.systemui.R
+import com.android.systemui.dagger.SysUISingleton
+import com.android.systemui.dagger.qualifiers.Background
+import com.android.systemui.util.NotificationChannels
+import java.text.NumberFormat
+import javax.inject.Inject
+
+/**
+ * UI controller for the notification that shows when a USI stylus battery is low. The
+ * [StylusUsiPowerStartable], which listens to battery events, uses this controller.
+ */
+@SysUISingleton
+class StylusUsiPowerUI
+@Inject
+constructor(
+    private val context: Context,
+    private val notificationManager: NotificationManagerCompat,
+    private val inputManager: InputManager,
+    @Background private val handler: Handler,
+) {
+
+    // These values must only be accessed on the handler.
+    private var batteryCapacity = 1.0f
+    private var suppressed = false
+
+    fun init() {
+        val filter =
+            IntentFilter().also {
+                it.addAction(ACTION_DISMISSED_LOW_BATTERY)
+                it.addAction(ACTION_CLICKED_LOW_BATTERY)
+            }
+
+        context.registerReceiverAsUser(
+            receiver,
+            UserHandle.ALL,
+            filter,
+            Manifest.permission.DEVICE_POWER,
+            handler,
+            Context.RECEIVER_NOT_EXPORTED,
+        )
+    }
+
+    fun refresh() {
+        handler.post refreshNotification@{
+            if (!suppressed && !hasConnectedBluetoothStylus() && isBatteryBelowThreshold()) {
+                showOrUpdateNotification()
+                return@refreshNotification
+            }
+
+            if (!isBatteryBelowThreshold()) {
+                // Reset suppression when stylus battery is recharged, so that the next time
+                // it reaches a low battery, the notification will show again.
+                suppressed = false
+            }
+            hideNotification()
+        }
+    }
+
+    fun updateBatteryState(batteryState: BatteryState) {
+        handler.post updateBattery@{
+            if (batteryState.capacity == batteryCapacity) return@updateBattery
+
+            batteryCapacity = batteryState.capacity
+            refresh()
+        }
+    }
+
+    /**
+     * Suppression happens when the notification is dismissed by the user. This is to prevent
+     * further battery events with capacities below the threshold from reopening the suppressed
+     * notification.
+     *
+     * Suppression can only be removed when the battery has been recharged - thus restarting the
+     * notification cycle (i.e. next low battery event, notification should show).
+     */
+    fun updateSuppression(suppress: Boolean) {
+        handler.post updateSuppressed@{
+            if (suppressed == suppress) return@updateSuppressed
+
+            suppressed = suppress
+            refresh()
+        }
+    }
+
+    private fun hideNotification() {
+        notificationManager.cancel(USI_NOTIFICATION_ID)
+    }
+
+    private fun showOrUpdateNotification() {
+        val notification =
+            NotificationCompat.Builder(context, NotificationChannels.BATTERY)
+                .setSmallIcon(R.drawable.ic_power_low)
+                .setDeleteIntent(getPendingBroadcast(ACTION_DISMISSED_LOW_BATTERY))
+                .setContentIntent(getPendingBroadcast(ACTION_CLICKED_LOW_BATTERY))
+                .setContentTitle(context.getString(R.string.stylus_battery_low))
+                .setContentText(
+                    context.getString(
+                        R.string.battery_low_percent_format,
+                        NumberFormat.getPercentInstance().format(batteryCapacity)
+                    )
+                )
+                .setPriority(NotificationCompat.PRIORITY_DEFAULT)
+                .setLocalOnly(true)
+                .setAutoCancel(true)
+                .build()
+
+        notificationManager.notify(USI_NOTIFICATION_ID, notification)
+    }
+
+    private fun isBatteryBelowThreshold(): Boolean {
+        return batteryCapacity <= LOW_BATTERY_THRESHOLD
+    }
+
+    private fun hasConnectedBluetoothStylus(): Boolean {
+        // TODO(b/257936830): get bt address once input api available
+        return inputManager.inputDeviceIds.any { deviceId ->
+            inputManager.getInputDevice(deviceId).supportsSource(InputDevice.SOURCE_STYLUS)
+        }
+    }
+
+    private fun getPendingBroadcast(action: String): PendingIntent? {
+        return PendingIntent.getBroadcastAsUser(
+            context,
+            0,
+            Intent(action),
+            PendingIntent.FLAG_IMMUTABLE,
+            UserHandle.CURRENT
+        )
+    }
+
+    private val receiver: BroadcastReceiver =
+        object : BroadcastReceiver() {
+            override fun onReceive(context: Context, intent: Intent) {
+                when (intent.action) {
+                    ACTION_DISMISSED_LOW_BATTERY -> updateSuppression(true)
+                    ACTION_CLICKED_LOW_BATTERY -> {
+                        updateSuppression(true)
+                        // TODO(b/261584943): open USI device details page
+                    }
+                }
+            }
+        }
+
+    companion object {
+        // Low battery threshold matches CrOS, see:
+        // https://source.chromium.org/chromium/chromium/src/+/main:ash/system/power/peripheral_battery_notifier.cc;l=41
+        private const val LOW_BATTERY_THRESHOLD = 0.16f
+
+        private val USI_NOTIFICATION_ID = R.string.stylus_battery_low
+
+        private const val ACTION_DISMISSED_LOW_BATTERY = "StylusUsiPowerUI.dismiss"
+        private const val ACTION_CLICKED_LOW_BATTERY = "StylusUsiPowerUI.click"
+    }
+}

packages/SystemUI/tests/src/com/android/systemui/stylus/StylusUsiPowerStartableTest.kt

@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2022 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.stylus
+
+import android.hardware.BatteryState
+import android.hardware.input.InputManager
+import android.testing.AndroidTestingRunner
+import android.view.InputDevice
+import androidx.test.filters.SmallTest
+import com.android.systemui.SysuiTestCase
+import com.android.systemui.flags.FeatureFlags
+import com.android.systemui.flags.Flags
+import com.android.systemui.util.mockito.whenever
+import java.util.concurrent.Executor
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.Mockito.inOrder
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.never
+import org.mockito.Mockito.times
+import org.mockito.Mockito.verify
+import org.mockito.Mockito.verifyNoMoreInteractions
+import org.mockito.MockitoAnnotations
+
+@RunWith(AndroidTestingRunner::class)
+@SmallTest
+class StylusUsiPowerStartableTest : SysuiTestCase() {
+    @Mock lateinit var inputManager: InputManager
+    @Mock lateinit var stylusManager: StylusManager
+    @Mock lateinit var stylusDevice: InputDevice
+    @Mock lateinit var externalDevice: InputDevice
+    @Mock lateinit var featureFlags: FeatureFlags
+    @Mock lateinit var stylusUsiPowerUi: StylusUsiPowerUI
+
+    lateinit var startable: StylusUsiPowerStartable
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+
+        startable =
+            StylusUsiPowerStartable(
+                stylusManager,
+                inputManager,
+                stylusUsiPowerUi,
+                featureFlags,
+                DIRECT_EXECUTOR,
+            )
+
+        whenever(featureFlags.isEnabled(Flags.ENABLE_USI_BATTERY_NOTIFICATIONS)).thenReturn(true)
+
+        whenever(inputManager.getInputDevice(EXTERNAL_DEVICE_ID)).thenReturn(externalDevice)
+        whenever(inputManager.getInputDevice(STYLUS_DEVICE_ID)).thenReturn(stylusDevice)
+        whenever(inputManager.inputDeviceIds)
+            .thenReturn(intArrayOf(EXTERNAL_DEVICE_ID, STYLUS_DEVICE_ID))
+
+        whenever(stylusDevice.supportsSource(InputDevice.SOURCE_STYLUS)).thenReturn(true)
+        whenever(stylusDevice.isExternal).thenReturn(false)
+        whenever(stylusDevice.id).thenReturn(STYLUS_DEVICE_ID)
+        whenever(externalDevice.supportsSource(InputDevice.SOURCE_STYLUS)).thenReturn(true)
+        whenever(externalDevice.isExternal).thenReturn(true)
+        whenever(externalDevice.id).thenReturn(EXTERNAL_DEVICE_ID)
+    }
+
+    @Test
+    fun start_addsBatteryListenerForInternalStylus() {
+        startable.start()
+
+        verify(inputManager, times(1))
+            .addInputDeviceBatteryListener(STYLUS_DEVICE_ID, DIRECT_EXECUTOR, startable)
+    }
+
+    @Test
+    fun onStylusAdded_internalStylus_addsBatteryListener() {
+        startable.onStylusAdded(STYLUS_DEVICE_ID)
+
+        verify(inputManager, times(1))
+            .addInputDeviceBatteryListener(STYLUS_DEVICE_ID, DIRECT_EXECUTOR, startable)
+    }
+
+    @Test
+    fun onStylusAdded_externalStylus_doesNotAddBatteryListener() {
+        startable.onStylusAdded(EXTERNAL_DEVICE_ID)
+
+        verify(inputManager, never())
+            .addInputDeviceBatteryListener(EXTERNAL_DEVICE_ID, DIRECT_EXECUTOR, startable)
+    }
+
+    @Test
+    fun onStylusRemoved_registeredStylus_removesBatteryListener() {
+        startable.onStylusAdded(STYLUS_DEVICE_ID)
+        startable.onStylusRemoved(STYLUS_DEVICE_ID)
+
+        inOrder(inputManager).let {
+            it.verify(inputManager, times(1))
+                .addInputDeviceBatteryListener(STYLUS_DEVICE_ID, DIRECT_EXECUTOR, startable)
+            it.verify(inputManager, times(1))
+                .removeInputDeviceBatteryListener(STYLUS_DEVICE_ID, startable)
+        }
+    }
+
+    @Test
+    fun onStylusBluetoothConnected_refreshesNotification() {
+        startable.onStylusBluetoothConnected(STYLUS_DEVICE_ID, "ANY")
+
+        verify(stylusUsiPowerUi, times(1)).refresh()
+    }
+
+    @Test
+    fun onStylusBluetoothDisconnected_refreshesNotification() {
+        startable.onStylusBluetoothDisconnected(STYLUS_DEVICE_ID, "ANY")
+
+        verify(stylusUsiPowerUi, times(1)).refresh()
+    }
+
+    @Test
+    fun onBatteryStateChanged_batteryPresent_refreshesNotification() {
+        val batteryState = mock(BatteryState::class.java)
+        whenever(batteryState.isPresent).thenReturn(true)
+
+        startable.onBatteryStateChanged(STYLUS_DEVICE_ID, 123, batteryState)
+
+        verify(stylusUsiPowerUi, times(1)).updateBatteryState(batteryState)
+    }
+
+    @Test
+    fun onBatteryStateChanged_batteryNotPresent_noop() {
+        val batteryState = mock(BatteryState::class.java)
+        whenever(batteryState.isPresent).thenReturn(false)
+
+        startable.onBatteryStateChanged(STYLUS_DEVICE_ID, 123, batteryState)
+
+        verifyNoMoreInteractions(stylusUsiPowerUi)
+    }
+
+    companion object {
+        private val DIRECT_EXECUTOR = Executor { r -> r.run() }
+
+        private const val EXTERNAL_DEVICE_ID = 0
+        private const val STYLUS_DEVICE_ID = 1
+    }
+}

packages/SystemUI/tests/src/com/android/systemui/stylus/StylusUsiPowerUiTest.kt

@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2022 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.stylus
+
+import android.hardware.BatteryState
+import android.hardware.input.InputManager
+import android.os.Handler
+import android.testing.AndroidTestingRunner
+import android.view.InputDevice
+import androidx.core.app.NotificationManagerCompat
+import androidx.test.filters.SmallTest
+import com.android.systemui.R
+import com.android.systemui.SysuiTestCase
+import com.android.systemui.util.mockito.any
+import com.android.systemui.util.mockito.eq
+import com.android.systemui.util.mockito.whenever
+import org.junit.Before
+import org.junit.Ignore
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.Mockito.inOrder
+import org.mockito.Mockito.times
+import org.mockito.Mockito.verify
+import org.mockito.Mockito.verifyNoMoreInteractions
+import org.mockito.MockitoAnnotations
+
+@RunWith(AndroidTestingRunner::class)
+@SmallTest
+class StylusUsiPowerUiTest : SysuiTestCase() {
+    @Mock lateinit var notificationManager: NotificationManagerCompat
+    @Mock lateinit var inputManager: InputManager
+    @Mock lateinit var handler: Handler
+    @Mock lateinit var btStylusDevice: InputDevice
+
+    private lateinit var stylusUsiPowerUi: StylusUsiPowerUI
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+
+        whenever(handler.post(any())).thenAnswer {
+            (it.arguments[0] as Runnable).run()
+            true
+        }
+
+        whenever(inputManager.inputDeviceIds).thenReturn(intArrayOf())
+        whenever(inputManager.getInputDevice(0)).thenReturn(btStylusDevice)
+        whenever(btStylusDevice.supportsSource(InputDevice.SOURCE_STYLUS)).thenReturn(true)
+        // whenever(btStylusDevice.bluetoothAddress).thenReturn("SO:ME:AD:DR:ES")
+
+        stylusUsiPowerUi = StylusUsiPowerUI(mContext, notificationManager, inputManager, handler)
+    }
+
+    @Test
+    fun updateBatteryState_capacityBelowThreshold_notifies() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+
+        verify(notificationManager, times(1)).notify(eq(R.string.stylus_battery_low), any())
+        verifyNoMoreInteractions(notificationManager)
+    }
+
+    @Test
+    fun updateBatteryState_capacityAboveThreshold_cancelsNotificattion() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.8f))
+
+        verify(notificationManager, times(1)).cancel(R.string.stylus_battery_low)
+        verifyNoMoreInteractions(notificationManager)
+    }
+
+    @Test
+    fun updateBatteryState_existingNotification_capacityAboveThreshold_cancelsNotification() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.8f))
+
+        inOrder(notificationManager).let {
+            it.verify(notificationManager, times(1)).notify(eq(R.string.stylus_battery_low), any())
+            it.verify(notificationManager, times(1)).cancel(R.string.stylus_battery_low)
+            it.verifyNoMoreInteractions()
+        }
+    }
+
+    @Test
+    fun updateBatteryState_existingNotification_capacityBelowThreshold_updatesNotification() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.15f))
+
+        verify(notificationManager, times(2)).notify(eq(R.string.stylus_battery_low), any())
+        verifyNoMoreInteractions(notificationManager)
+    }
+
+    @Test
+    fun updateBatteryState_capacityAboveThenBelowThreshold_hidesThenShowsNotification() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.5f))
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+
+        inOrder(notificationManager).let {
+            it.verify(notificationManager, times(1)).notify(eq(R.string.stylus_battery_low), any())
+            it.verify(notificationManager, times(1)).cancel(R.string.stylus_battery_low)
+            it.verify(notificationManager, times(1)).notify(eq(R.string.stylus_battery_low), any())
+            it.verifyNoMoreInteractions()
+        }
+    }
+
+    @Test
+    fun updateSuppression_noExistingNotification_cancelsNotification() {
+        stylusUsiPowerUi.updateSuppression(true)
+
+        verify(notificationManager, times(1)).cancel(R.string.stylus_battery_low)
+        verifyNoMoreInteractions(notificationManager)
+    }
+
+    @Test
+    fun updateSuppression_existingNotification_cancelsNotification() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+
+        stylusUsiPowerUi.updateSuppression(true)
+
+        inOrder(notificationManager).let {
+            it.verify(notificationManager, times(1)).notify(eq(R.string.stylus_battery_low), any())
+            it.verify(notificationManager, times(1)).cancel(R.string.stylus_battery_low)
+            it.verifyNoMoreInteractions()
+        }
+    }
+
+    @Test
+    @Ignore("TODO(b/257936830): get bt address once input api available")
+    fun refresh_hasConnectedBluetoothStylus_doesNotNotify() {
+        whenever(inputManager.inputDeviceIds).thenReturn(intArrayOf(0))
+
+        stylusUsiPowerUi.refresh()
+
+        verifyNoMoreInteractions(notificationManager)
+    }
+
+    @Test
+    @Ignore("TODO(b/257936830): get bt address once input api available")
+    fun refresh_hasConnectedBluetoothStylus_existingNotification_cancelsNotification() {
+        stylusUsiPowerUi.updateBatteryState(FixedCapacityBatteryState(0.1f))
+        whenever(inputManager.inputDeviceIds).thenReturn(intArrayOf(0))
+
+        stylusUsiPowerUi.refresh()
+
+        verify(notificationManager).cancel(R.string.stylus_battery_low)
+    }
+
+    class FixedCapacityBatteryState(private val capacity: Float) : BatteryState() {
+        override fun getCapacity() = capacity
+        override fun getStatus() = 0
+        override fun isPresent() = true
+    }
+}