Refactor the SADeviceState to AdiDeviceState

The idea is to have a device state catalog for all the known devices.
Also refactored the name of the Settings.Secure key entry for
persistence. The current code will check the legacy key first, erase
it and update the new key.

Test: atest SpatializerHelperTest & AudioDeviceBrokerTest
Bug: 278265907
Bug: 285588444
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:718d89772105c8153b3850b149691fbe540b692d)
Merged-In: Idabcc84cb0f5f6f88ba5aebc435511ab95016ef3
Change-Id: Idabcc84cb0f5f6f88ba5aebc435511ab95016ef3

7 files changed, 465 insertions, 2 deletions

diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index ac520e8b3dec..355fdac214f9 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -8964,6 +8964,13 @@ public final class Settings {
         public static final String UNSAFE_VOLUME_MUSIC_ACTIVE_MS = "unsafe_volume_music_active_ms";
 
         /**
+         * Internal collection of audio device inventory items
+         * The device item stored are {@link com.android.server.audio.AdiDeviceState}
+         * @hide
+         */
+        public static final String AUDIO_DEVICE_INVENTORY = "audio_device_inventory";
+
+        /**
          * Indicates whether notification display on the lock screen is enabled.
          * <p>
          * Type: int (0 for false, 1 for true)
diff --git a/media/java/android/media/AudioSystem.java b/media/java/android/media/AudioSystem.java
index 69d1889d5762..9736f8d8bd63 100644
--- a/media/java/android/media/AudioSystem.java
+++ b/media/java/android/media/AudioSystem.java
@@ -1119,6 +1119,9 @@ public class AudioSystem
     public static final Set<Integer> DEVICE_IN_ALL_SCO_SET;
     /** @hide */
     public static final Set<Integer> DEVICE_IN_ALL_USB_SET;
+    /** @hide */
+    public static final Set<Integer> DEVICE_IN_ALL_BLE_SET;
+
     static {
         DEVICE_IN_ALL_SET = new HashSet<>();
         DEVICE_IN_ALL_SET.add(DEVICE_IN_COMMUNICATION);
@@ -1158,6 +1161,66 @@ public class AudioSystem
         DEVICE_IN_ALL_USB_SET.add(DEVICE_IN_USB_ACCESSORY);
         DEVICE_IN_ALL_USB_SET.add(DEVICE_IN_USB_DEVICE);
         DEVICE_IN_ALL_USB_SET.add(DEVICE_IN_USB_HEADSET);
+
+        DEVICE_IN_ALL_BLE_SET = new HashSet<>();
+        DEVICE_IN_ALL_BLE_SET.add(DEVICE_IN_BLE_HEADSET);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothDevice(int deviceType) {
+        return isBluetoothA2dpOutDevice(deviceType)
+                || isBluetoothScoDevice(deviceType)
+                || isBluetoothLeDevice(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothOutDevice(int deviceType) {
+        return isBluetoothA2dpOutDevice(deviceType)
+                || isBluetoothScoOutDevice(deviceType)
+                || isBluetoothLeOutDevice(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothInDevice(int deviceType) {
+        return isBluetoothScoInDevice(deviceType)
+                || isBluetoothLeInDevice(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothA2dpOutDevice(int deviceType) {
+        return DEVICE_OUT_ALL_A2DP_SET.contains(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothScoOutDevice(int deviceType) {
+        return DEVICE_OUT_ALL_SCO_SET.contains(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothScoInDevice(int deviceType) {
+        return DEVICE_IN_ALL_SCO_SET.contains(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothScoDevice(int deviceType) {
+        return isBluetoothScoOutDevice(deviceType)
+                || isBluetoothScoInDevice(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothLeOutDevice(int deviceType) {
+        return DEVICE_OUT_ALL_BLE_SET.contains(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothLeInDevice(int deviceType) {
+        return DEVICE_IN_ALL_BLE_SET.contains(deviceType);
+    }
+
+    /** @hide */
+    public static boolean isBluetoothLeDevice(int deviceType) {
+        return isBluetoothLeOutDevice(deviceType)
+                || isBluetoothLeInDevice(deviceType);
     }
 
     /** @hide */
diff --git a/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java b/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java
index 3297937e3e75..009ccfdb37d2 100644
--- a/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java
+++ b/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java
@@ -615,6 +615,7 @@ public class SettingsBackupTest {
                  Settings.Secure.ASSIST_SCREENSHOT_ENABLED,
                  Settings.Secure.ASSIST_STRUCTURE_ENABLED,
                  Settings.Secure.ATTENTIVE_TIMEOUT,
+                 Settings.Secure.AUDIO_DEVICE_INVENTORY, // setting not controllable by user
                  Settings.Secure.AUTOFILL_FEATURE_FIELD_CLASSIFICATION,
                  Settings.Secure.AUTOFILL_USER_DATA_MAX_CATEGORY_COUNT,
                  Settings.Secure.AUTOFILL_USER_DATA_MAX_FIELD_CLASSIFICATION_IDS_SIZE,
diff --git a/services/core/java/com/android/server/audio/AdiDeviceState.java b/services/core/java/com/android/server/audio/AdiDeviceState.java
new file mode 100644
index 000000000000..a27daf65b9f9
--- /dev/null
+++ b/services/core/java/com/android/server/audio/AdiDeviceState.java
@@ -0,0 +1,206 @@
+/*
+ * 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.server.audio;
+
+import static android.media.AudioSystem.DEVICE_NONE;
+import static android.media.AudioSystem.isBluetoothDevice;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.media.AudioDeviceAttributes;
+import android.media.AudioDeviceInfo;
+import android.text.TextUtils;
+import android.util.Log;
+
+import java.util.Objects;
+
+/**
+ * Class representing all devices that were previously or are currently connected. Data is
+ * persisted in {@link android.provider.Settings.Secure}
+ */
+/*package*/ final class AdiDeviceState {
+    private static final String TAG = "AS.AdiDeviceState";
+
+    private static final String SETTING_FIELD_SEPARATOR = ",";
+
+    @AudioDeviceInfo.AudioDeviceType
+    private final int mDeviceType;
+
+    private final int mInternalDeviceType;
+    @NonNull
+    private final String mDeviceAddress;
+    private boolean mSAEnabled;
+    private boolean mHasHeadTracker = false;
+    private boolean mHeadTrackerEnabled;
+
+    /**
+     * Constructor
+     *
+     * @param deviceType external audio device type
+     * @param internalDeviceType if not set pass {@link DEVICE_NONE}, in this case the
+     *                           default conversion of the external type will be used
+     * @param address must be non-null for wireless devices
+     * @throws NullPointerException if a null address is passed for a wireless device
+     */
+    AdiDeviceState(@AudioDeviceInfo.AudioDeviceType int deviceType,
+                        int internalDeviceType,
+                        @Nullable String address) {
+        mDeviceType = deviceType;
+        if (internalDeviceType != DEVICE_NONE) {
+            mInternalDeviceType = internalDeviceType;
+        } else {
+            mInternalDeviceType = AudioDeviceInfo.convertDeviceTypeToInternalDevice(deviceType);
+
+        }
+        mDeviceAddress = isBluetoothDevice(mInternalDeviceType) ? Objects.requireNonNull(
+                address) : "";
+    }
+
+
+
+    @AudioDeviceInfo.AudioDeviceType
+    public int getDeviceType() {
+        return mDeviceType;
+    }
+
+    public int getInternalDeviceType() {
+        return mInternalDeviceType;
+    }
+
+    @NonNull
+    public String getDeviceAddress() {
+        return mDeviceAddress;
+    }
+
+    public void setSAEnabled(boolean sAEnabled) {
+        mSAEnabled = sAEnabled;
+    }
+
+    public boolean isSAEnabled() {
+        return mSAEnabled;
+    }
+
+    public void setHeadTrackerEnabled(boolean headTrackerEnabled) {
+        mHeadTrackerEnabled = headTrackerEnabled;
+    }
+
+    public boolean isHeadTrackerEnabled() {
+        return mHeadTrackerEnabled;
+    }
+
+    public void setHasHeadTracker(boolean hasHeadTracker) {
+        mHasHeadTracker = hasHeadTracker;
+    }
+
+
+    public boolean hasHeadTracker() {
+        return mHasHeadTracker;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        // type check and cast
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        final AdiDeviceState sads = (AdiDeviceState) obj;
+        return mDeviceType == sads.mDeviceType
+                && mInternalDeviceType == sads.mInternalDeviceType
+                && mDeviceAddress.equals(sads.mDeviceAddress)  // NonNull
+                && mSAEnabled == sads.mSAEnabled
+                && mHasHeadTracker == sads.mHasHeadTracker
+                && mHeadTrackerEnabled == sads.mHeadTrackerEnabled;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(mDeviceType, mInternalDeviceType, mDeviceAddress, mSAEnabled,
+                mHasHeadTracker, mHeadTrackerEnabled);
+    }
+
+    @Override
+    public String toString() {
+        return "type: " + mDeviceType + "internal type: " + mInternalDeviceType
+                + " addr: " + mDeviceAddress + " enabled: " + mSAEnabled
+                + " HT: " + mHasHeadTracker + " HTenabled: " + mHeadTrackerEnabled;
+    }
+
+    public String toPersistableString() {
+        return (new StringBuilder().append(mDeviceType)
+                .append(SETTING_FIELD_SEPARATOR).append(mDeviceAddress)
+                .append(SETTING_FIELD_SEPARATOR).append(mSAEnabled ? "1" : "0")
+                .append(SETTING_FIELD_SEPARATOR).append(mHasHeadTracker ? "1" : "0")
+                .append(SETTING_FIELD_SEPARATOR).append(mHeadTrackerEnabled ? "1" : "0")
+                .append(SETTING_FIELD_SEPARATOR).append(mInternalDeviceType)
+                .toString());
+    }
+
+    /**
+     * Gets the max size (including separators) when persisting the elements with
+     * {@link AdiDeviceState#toPersistableString()}.
+     */
+    public static int getPeristedMaxSize() {
+        return 36;  /* (mDeviceType)2 + (mDeviceAddresss)17 + (mInternalDeviceType)9 + (mSAEnabled)1
+                           + (mHasHeadTracker)1 + (mHasHeadTrackerEnabled)1
+                           + (SETTINGS_FIELD_SEPARATOR)5 */
+    }
+
+    @Nullable
+    public static AdiDeviceState fromPersistedString(@Nullable String persistedString) {
+        if (persistedString == null) {
+            return null;
+        }
+        if (persistedString.isEmpty()) {
+            return null;
+        }
+        String[] fields = TextUtils.split(persistedString, SETTING_FIELD_SEPARATOR);
+        // we may have 5 fields for the legacy AdiDeviceState and 6 containing the internal
+        // device type
+        if (fields.length != 5 && fields.length != 6) {
+            // expecting all fields, fewer may mean corruption, ignore those settings
+            return null;
+        }
+        try {
+            final int deviceType = Integer.parseInt(fields[0]);
+            int internalDeviceType = -1;
+            if (fields.length == 6) {
+                internalDeviceType = Integer.parseInt(fields[5]);
+            }
+            final AdiDeviceState deviceState = new AdiDeviceState(deviceType,
+                    internalDeviceType, fields[1]);
+            deviceState.setHasHeadTracker(Integer.parseInt(fields[2]) == 1);
+            deviceState.setHasHeadTracker(Integer.parseInt(fields[3]) == 1);
+            deviceState.setHeadTrackerEnabled(Integer.parseInt(fields[4]) == 1);
+            return deviceState;
+        } catch (NumberFormatException e) {
+            Log.e(TAG, "unable to parse setting for AdiDeviceState: " + persistedString, e);
+            return null;
+        }
+    }
+
+    public AudioDeviceAttributes getAudioDeviceAttributes() {
+        return new AudioDeviceAttributes(AudioDeviceAttributes.ROLE_OUTPUT,
+                mDeviceType, mDeviceAddress);
+    }
+
+}
diff --git a/services/core/java/com/android/server/audio/AudioDeviceBroker.java b/services/core/java/com/android/server/audio/AudioDeviceBroker.java
index 8961a5a05546..ec439a85b186 100644
--- a/services/core/java/com/android/server/audio/AudioDeviceBroker.java
+++ b/services/core/java/com/android/server/audio/AudioDeviceBroker.java
@@ -47,6 +47,7 @@ import android.os.RemoteCallbackList;
 import android.os.RemoteException;
 import android.os.SystemClock;
 import android.os.UserHandle;
+import android.provider.Settings;
 import android.text.TextUtils;
 import android.util.Log;
 import android.util.PrintWriterPrinter;
@@ -63,8 +64,11 @@ import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 
-/** @hide */
-/*package*/ final class AudioDeviceBroker {
+/**
+ * @hide
+ * (non final for mocking/spying)
+ */
+public class AudioDeviceBroker {
 
     private static final String TAG = "AS.AudioDeviceBroker";
 
@@ -1415,6 +1419,9 @@ import java.util.concurrent.atomic.AtomicBoolean;
                     final int capturePreset = msg.arg1;
                     mDeviceInventory.onSaveClearPreferredDevicesForCapturePreset(capturePreset);
                 } break;
+                case MSG_PERSIST_AUDIO_DEVICE_SETTINGS:
+                    onPersistAudioDeviceSettings();
+                    break;
                 default:
                     Log.wtf(TAG, "Invalid message " + msg.what);
             }
@@ -1496,6 +1503,8 @@ import java.util.concurrent.atomic.AtomicBoolean;
     private static final int MSG_IL_SET_PREF_DEVICES_FOR_STRATEGY = 40;
     private static final int MSG_I_REMOVE_PREF_DEVICES_FOR_STRATEGY = 41;
 
+    private static final int MSG_PERSIST_AUDIO_DEVICE_SETTINGS = 54;
+
     private static boolean isMessageHandledUnderWakelock(int msgId) {
         switch(msgId) {
             case MSG_L_SET_WIRED_DEVICE_CONNECTION_STATE:
@@ -1842,4 +1851,65 @@ import java.util.concurrent.atomic.AtomicBoolean;
         }
         return null;
     }
+
+    /**
+     * post a message to persist the audio device settings.
+     * Message is delayed by 1s on purpose in case of successive changes in quick succession (at
+     * init time for instance)
+     * Note this method is made public to work around a Mockito bug where it needs to be public
+     * in order to be mocked by a test a the same package
+     * (see https://code.google.com/archive/p/mockito/issues/127)
+     */
+    public void persistAudioDeviceSettings() {
+        sendMsg(MSG_PERSIST_AUDIO_DEVICE_SETTINGS, SENDMSG_REPLACE, /*delay*/ 1000);
+    }
+
+    void onPersistAudioDeviceSettings() {
+        final String deviceSettings = mDeviceInventory.getDeviceSettings();
+        Log.v(TAG, "saving audio device settings: " + deviceSettings);
+        boolean res = Settings.Secure.putStringForUser(
+                mAudioService.getContentResolver(), Settings.Secure.AUDIO_DEVICE_INVENTORY,
+                deviceSettings, UserHandle.USER_CURRENT);
+
+        if (!res) {
+            Log.e(TAG, "error saving audio device settings: " + deviceSettings);
+        }
+    }
+
+    void onReadAudioDeviceSettings() {
+        final ContentResolver contentResolver = mAudioService.getContentResolver();
+        String settings = Settings.Secure.getStringForUser(contentResolver,
+                Settings.Secure.AUDIO_DEVICE_INVENTORY, UserHandle.USER_CURRENT);
+        if (settings != null && !settings.equals("")) {
+            setDeviceSettings(settings);
+        }
+    }
+
+    void setDeviceSettings(String settings) {
+        mDeviceInventory.setDeviceSettings(settings);
+    }
+
+    /** Test only method. */
+    String getDeviceSettings() {
+        return mDeviceInventory.getDeviceSettings();
+    }
+
+    List<AdiDeviceState> getImmutableDeviceInventory() {
+        return mDeviceInventory.getImmutableDeviceInventory();
+    }
+
+    void addDeviceStateToInventory(AdiDeviceState deviceState) {
+        mDeviceInventory.addDeviceStateToInventory(deviceState);
+    }
+
+    AdiDeviceState findDeviceStateForAudioDeviceAttributes(AudioDeviceAttributes ada,
+            int canonicalType) {
+        return mDeviceInventory.findDeviceStateForAudioDeviceAttributes(ada, canonicalType);
+    }
+
+    //------------------------------------------------
+    // for testing purposes only
+    void clearDeviceInventory() {
+        mDeviceInventory.clearDeviceInventory();
+    }
 }
diff --git a/services/core/java/com/android/server/audio/AudioDeviceInventory.java b/services/core/java/com/android/server/audio/AudioDeviceInventory.java
index 5944a63bd5e6..0e4c4c6ccb6f 100644
--- a/services/core/java/com/android/server/audio/AudioDeviceInventory.java
+++ b/services/core/java/com/android/server/audio/AudioDeviceInventory.java
@@ -15,6 +15,8 @@
  */
 package com.android.server.audio;
 
+import static android.media.AudioSystem.isBluetoothDevice;
+
 import android.annotation.NonNull;
 import android.bluetooth.BluetoothA2dp;
 import android.bluetooth.BluetoothAdapter;
@@ -61,12 +63,54 @@ public class AudioDeviceInventory {
 
     private static final String TAG = "AS.AudioDeviceInventory";
 
+    private static final String SETTING_DEVICE_SEPARATOR_CHAR = "|";
+    private static final String SETTING_DEVICE_SEPARATOR = "\\|";
+
     // lock to synchronize all access to mConnectedDevices and mApmConnectedDevices
     private final Object mDevicesLock = new Object();
 
     //Audio Analytics ids.
     private static final String mMetricsId = "audio.device.";
 
+    private final Object mDeviceInventoryLock = new Object();
+    @GuardedBy("mDeviceInventoryLock")
+    private final ArrayList<AdiDeviceState> mDeviceInventory = new ArrayList<>(0);
+
+
+    List<AdiDeviceState> getImmutableDeviceInventory() {
+        synchronized (mDeviceInventoryLock) {
+            return List.copyOf(mDeviceInventory);
+        }
+    }
+
+    void addDeviceStateToInventory(AdiDeviceState deviceState) {
+        synchronized (mDeviceInventoryLock) {
+            mDeviceInventory.add(deviceState);
+        }
+    }
+
+    AdiDeviceState findDeviceStateForAudioDeviceAttributes(AudioDeviceAttributes ada,
+            int canonicalDeviceType) {
+        final boolean isWireless = isBluetoothDevice(ada.getInternalType());
+
+        synchronized (mDeviceInventoryLock) {
+            for (AdiDeviceState deviceSetting : mDeviceInventory) {
+                if (deviceSetting.getDeviceType() == canonicalDeviceType
+                        && (!isWireless || ada.getAddress().equals(
+                        deviceSetting.getDeviceAddress()))) {
+                    return deviceSetting;
+                }
+            }
+        }
+        return null;
+    }
+
+    void clearDeviceInventory() {
+        synchronized (mDeviceInventoryLock) {
+            mDeviceInventory.clear();
+        }
+    }
+
     // List of connected devices
     // Key for map created from DeviceInfo.makeDeviceListKey()
     @GuardedBy("mDevicesLock")
@@ -253,6 +297,12 @@ public class AudioDeviceInventory {
         mPreferredDevicesForCapturePreset.forEach((capturePreset, devices) -> {
             pw.println("  " + prefix + "capturePreset:" + capturePreset
                     + " devices:" + devices); });
+        pw.println("\ndevices:\n");
+        synchronized (mDeviceInventoryLock) {
+            for (AdiDeviceState device : mDeviceInventory) {
+                pw.println("\t" + device + "\n");
+            }
+        }
     }
 
     //------------------------------------------------------------
@@ -1393,6 +1443,40 @@ public class AudioDeviceInventory {
         mDevRoleCapturePresetDispatchers.finishBroadcast();
     }
 
+    /*package*/ String getDeviceSettings() {
+        int deviceCatalogSize = 0;
+        synchronized (mDeviceInventoryLock) {
+            deviceCatalogSize = mDeviceInventory.size();
+        }
+        final StringBuilder settingsBuilder = new StringBuilder(
+                deviceCatalogSize * AdiDeviceState.getPeristedMaxSize());
+
+        synchronized (mDeviceInventoryLock) {
+            for (int i = 0; i < mDeviceInventory.size(); i++) {
+                settingsBuilder.append(mDeviceInventory.get(i).toPersistableString());
+                if (i != mDeviceInventory.size() - 1) {
+                    settingsBuilder.append(SETTING_DEVICE_SEPARATOR_CHAR);
+                }
+            }
+        }
+        return settingsBuilder.toString();
+    }
+
+    /*package*/ void setDeviceSettings(String settings) {
+        clearDeviceInventory();
+        String[] devSettings = TextUtils.split(settings,
+                SETTING_DEVICE_SEPARATOR);
+        // small list, not worth overhead of Arrays.stream(devSettings)
+        for (String setting : devSettings) {
+            AdiDeviceState devState = AdiDeviceState.fromPersistedString(setting);
+            // Note if the device is not compatible with spatialization mode or the device
+            // type is not canonical, it will be ignored in {@link SpatializerHelper}.
+            if (devState != null) {
+                addDeviceStateToInventory(devState);
+            }
+        }
+    }
+
     //----------------------------------------------------------
     // For tests only
 
diff --git a/services/tests/servicestests/src/com/android/server/audio/AudioDeviceBrokerTest.java b/services/tests/servicestests/src/com/android/server/audio/AudioDeviceBrokerTest.java
index 5c53d43fa1df..d33ff03df02a 100644
--- a/services/tests/servicestests/src/com/android/server/audio/AudioDeviceBrokerTest.java
+++ b/services/tests/servicestests/src/com/android/server/audio/AudioDeviceBrokerTest.java
@@ -29,6 +29,7 @@ import android.bluetooth.BluetoothDevice;
 import android.bluetooth.BluetoothProfile;
 import android.content.Context;
 import android.content.Intent;
+import android.media.AudioDeviceInfo;
 import android.media.AudioManager;
 import android.media.AudioSystem;
 import android.util.Log;
@@ -199,6 +200,37 @@ public class AudioDeviceBrokerTest {
                 any(Intent.class));
     }
 
+    /**
+     * Test that constructing an AdiDeviceState instance requires a non-null address for a
+     * wireless type, but can take null for a non-wireless type;
+     * @throws Exception
+     */
+    @Test
+    public void testAdiDeviceStateNullAddressCtor() throws Exception {
+        try {
+            new AdiDeviceState(AudioDeviceInfo.TYPE_BUILTIN_SPEAKER,
+                    AudioManager.DEVICE_OUT_SPEAKER, null);
+            new AdiDeviceState(AudioDeviceInfo.TYPE_BLUETOOTH_A2DP,
+                    AudioManager.DEVICE_OUT_BLUETOOTH_A2DP, null);
+            Assert.fail();
+        } catch (NullPointerException e) { }
+    }
+
+    @Test
+    public void testAdiDeviceStateStringSerialization() throws Exception {
+        Log.i(TAG, "starting testAdiDeviceStateStringSerialization");
+        final AdiDeviceState devState = new AdiDeviceState(
+                AudioDeviceInfo.TYPE_BUILTIN_SPEAKER, AudioManager.DEVICE_OUT_SPEAKER, "bla");
+        devState.setHasHeadTracker(false);
+        devState.setHeadTrackerEnabled(false);
+        devState.setSAEnabled(true);
+        final String persistString = devState.toPersistableString();
+        final AdiDeviceState result = AdiDeviceState.fromPersistedString(persistString);
+        Log.i(TAG, "original:" + devState);
+        Log.i(TAG, "result  :" + result);
+        Assert.assertEquals(devState, result);
+    }
+
     private void doTestConnectionDisconnectionReconnection(int delayAfterDisconnection,
             boolean mockMediaPlayback, boolean guaranteeSingleConnection) throws Exception {
         when(mMockAudioService.getDeviceForStream(AudioManager.STREAM_MUSIC))