diff --git a/nearby/framework/java/android/nearby/FastPairClient.java b/nearby/framework/java/android/nearby/FastPairClient.java
new file mode 100644
index 0000000..7ac0481
--- /dev/null
+++ b/nearby/framework/java/android/nearby/FastPairClient.java
@@ -0,0 +1,94 @@
+/*
+ * 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 android.nearby;
+
+import android.annotation.BinderThread;
+import android.content.Context;
+import android.nearby.aidl.IFastPairClient;
+import android.nearby.aidl.IFastPairStatusCallback;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.util.Log;
+
+import java.lang.ref.WeakReference;
+
+/**
+ * 0p API for controlling Fast Pair. It communicates between main thread and service.
+ *
+ * @hide
+ */
+public class FastPairClient {
+
+    private static final String TAG = "FastPairClient";
+    private final IBinder mBinder;
+    private final WeakReference<Context> mWeakContext;
+    IFastPairClient mFastPairClient;
+    PairStatusCallbackIBinder mPairStatusCallbackIBinder;
+
+    public FastPairClient(Context context, IBinder binder) {
+        mBinder = binder;
+        mFastPairClient = IFastPairClient.Stub.asInterface(mBinder);
+        mWeakContext = new WeakReference<>(context);
+    }
+
+    /**
+     * Registers a callback at service to get UI updates.
+     */
+    public void registerHalfSheet(FastPairStatusCallback fastPairStatusCallback) {
+        if (mPairStatusCallbackIBinder != null) {
+            return;
+        }
+        mPairStatusCallbackIBinder = new PairStatusCallbackIBinder(fastPairStatusCallback);
+        try {
+            mFastPairClient.registerHalfSheet(mPairStatusCallbackIBinder);
+        } catch (RemoteException e) {
+            Log.w(TAG, "Failed to register fastPairStatusCallback", e);
+        }
+    }
+
+    /**
+     * Pairs the device at service.
+     */
+    public void connect(FastPairDevice fastPairDevice) {
+        try {
+            mFastPairClient.connect(fastPairDevice);
+        } catch (RemoteException e) {
+            Log.w(TAG, "Failed to connect Fast Pair device" + fastPairDevice, e);
+        }
+    }
+
+    private class PairStatusCallbackIBinder extends IFastPairStatusCallback.Stub {
+        private final FastPairStatusCallback mStatusCallback;
+
+        private PairStatusCallbackIBinder(FastPairStatusCallback fastPairStatusCallback) {
+            mStatusCallback = fastPairStatusCallback;
+        }
+
+        @BinderThread
+        @Override
+        public synchronized void onPairUpdate(FastPairDevice fastPairDevice,
+                PairStatusMetadata pairStatusMetadata) {
+            Context context = mWeakContext.get();
+            if (context != null) {
+                Handler handler = new Handler(context.getMainLooper());
+                handler.post(() ->
+                        mStatusCallback.onPairUpdate(fastPairDevice, pairStatusMetadata));
+            }
+        }
+    }
+}
diff --git a/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManager.java b/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManager.java
index ff0efc7..e7ce4bf 100644
--- a/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManager.java
+++ b/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManager.java
@@ -70,6 +70,11 @@
     private final FastPairConnection.FastPairSignalChecker mFastPairSignalChecker;
     @Nullable
     private BluetoothGattConnection mGattConnection;
+    private static boolean sTestMode = false;
+
+    static void enableTestMode() {
+        sTestMode = true;
+    }
 
     GattConnectionManager(
             Context context,
@@ -147,6 +152,9 @@
             try (ScopedTiming scopedTiming =
                     new ScopedTiming(mTimingLogger, "Connect GATT #" + i)) {
                 Log.i(TAG, "Connecting to GATT server at " + maskBluetoothAddress(address));
+                if (sTestMode) {
+                    return null;
+                }
                 BluetoothGattConnection connection =
                         new BluetoothGattHelper(mContext, mBluetoothAdapter)
                                 .connect(
diff --git a/nearby/service/java/com/android/server/nearby/provider/BleDiscoveryProvider.java b/nearby/service/java/com/android/server/nearby/provider/BleDiscoveryProvider.java
index fc2e4e8..a989143 100644
--- a/nearby/service/java/com/android/server/nearby/provider/BleDiscoveryProvider.java
+++ b/nearby/service/java/com/android/server/nearby/provider/BleDiscoveryProvider.java
@@ -21,6 +21,7 @@
 import android.annotation.Nullable;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.le.BluetoothLeScanner;
+import android.bluetooth.le.ScanCallback;
 import android.bluetooth.le.ScanFilter;
 import android.bluetooth.le.ScanRecord;
 import android.bluetooth.le.ScanResult;
@@ -37,6 +38,8 @@
 import com.android.server.nearby.presence.PresenceConstants;
 import com.android.server.nearby.util.ForegroundThread;
 
+import com.google.common.annotations.VisibleForTesting;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -47,7 +50,8 @@
  */
 public class BleDiscoveryProvider extends AbstractDiscoveryProvider {
 
-    private static final ParcelUuid FAST_PAIR_UUID = new ParcelUuid(Constants.FastPairService.ID);
+    @VisibleForTesting
+    static final ParcelUuid FAST_PAIR_UUID = new ParcelUuid(Constants.FastPairService.ID);
     private static final ParcelUuid PRESENCE_UUID = new ParcelUuid(PresenceConstants.PRESENCE_UUID);
 
     // Don't block the thread as it may be used by other services.
@@ -156,6 +160,7 @@
             if (bluetoothLeScanner == null) {
                 Log.w(TAG, "BleDiscoveryProvider failed to start BLE scanning "
                         + "because BluetoothLeScanner is null.");
+                return;
             }
             bluetoothLeScanner.startScan(scanFilters, scanSettings, scanCallback);
         } catch (NullPointerException | IllegalStateException | SecurityException e) {
@@ -188,4 +193,9 @@
         }
         return new ScanSettings.Builder().setScanMode(bleScanMode).build();
     }
+
+    @VisibleForTesting
+    ScanCallback getScanCallback() {
+        return mScanCallback;
+    }
 }
diff --git a/nearby/tests/unit/AndroidManifest.xml b/nearby/tests/unit/AndroidManifest.xml
index 86ce01b..88c0f5f 100644
--- a/nearby/tests/unit/AndroidManifest.xml
+++ b/nearby/tests/unit/AndroidManifest.xml
@@ -20,6 +20,8 @@
 
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.BLUETOOTH" />
+    <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
 
     <application android:debuggable="true">
         <uses-library android:name="android.test.runner" />
diff --git a/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java b/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java
new file mode 100644
index 0000000..c20cf22
--- /dev/null
+++ b/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java
@@ -0,0 +1,64 @@
+/*
+ * 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.server.nearby;
+
+import static org.mockito.MockitoAnnotations.initMocks;
+
+import android.content.Context;
+import android.nearby.IScanListener;
+import android.nearby.ScanRequest;
+
+import androidx.test.platform.app.InstrumentationRegistry;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+
+public final class NearbyServiceTest {
+
+    private Context mContext;
+    private NearbyService mService;
+    private ScanRequest mScanRequest;
+    @Mock
+    private IScanListener mScanListener;
+
+    @Before
+    public void setup() {
+        initMocks(this);
+
+        mContext = InstrumentationRegistry.getInstrumentation().getContext();
+        mService = new NearbyService(mContext);
+        mScanRequest = createScanRequest();
+    }
+
+    @Test
+    public void test_register() {
+        mService.registerScanListener(mScanRequest, mScanListener);
+    }
+
+    @Test
+    public void test_unregister() {
+        mService.unregisterScanListener(mScanListener);
+    }
+
+    private ScanRequest createScanRequest() {
+        return new ScanRequest.Builder()
+                .setScanType(ScanRequest.SCAN_TYPE_FAST_PAIR)
+                .setEnableBle(true)
+                .build();
+    }
+}
diff --git a/nearby/tests/unit/src/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManagerTest.java b/nearby/tests/unit/src/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManagerTest.java
new file mode 100644
index 0000000..2f80a30
--- /dev/null
+++ b/nearby/tests/unit/src/com/android/server/nearby/common/bluetooth/fastpair/GattConnectionManagerTest.java
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2021 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.nearby.common.bluetooth.fastpair;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.platform.test.annotations.Presubmit;
+
+import androidx.annotation.Nullable;
+import androidx.test.core.app.ApplicationProvider;
+import androidx.test.filters.SdkSuppress;
+import androidx.test.filters.SmallTest;
+
+import com.android.server.nearby.common.bluetooth.BluetoothException;
+import com.android.server.nearby.common.bluetooth.BluetoothGattException;
+import com.android.server.nearby.common.bluetooth.testability.android.bluetooth.BluetoothAdapter;
+import com.android.server.nearby.common.bluetooth.util.BluetoothOperationExecutor.BluetoothOperationTimeoutException;
+
+import com.google.common.collect.ImmutableSet;
+
+import junit.framework.TestCase;
+
+import java.time.Duration;
+import java.util.concurrent.ExecutionException;
+
+/**
+ * Unit tests for {@link GattConnectionManager}.
+ */
+@Presubmit
+@SmallTest
+public class GattConnectionManagerTest extends TestCase {
+
+    private static final String FAST_PAIR_ADDRESS = "BB:BB:BB:BB:BB:1E";
+
+    @Override
+    public void setUp() throws Exception {
+        super.setUp();
+
+        GattConnectionManager.enableTestMode();
+    }
+
+    @SdkSuppress(minSdkVersion = 32, codeName = "T")
+    public void testGattConnectionManagerConstructor() throws Exception {
+        GattConnectionManager manager = createManager(Preferences.builder());
+        try {
+            manager.getConnection();
+        } catch (ExecutionException e) {
+        }
+    }
+
+    @SdkSuppress(minSdkVersion = 32, codeName = "T")
+    public void testIsNoRetryError() {
+        Preferences preferences =
+                Preferences.builder()
+                        .setGattConnectionAndSecretHandshakeNoRetryGattError(
+                                ImmutableSet.of(257, 999))
+                        .build();
+
+        assertThat(
+                GattConnectionManager.isNoRetryError(
+                        preferences, new BluetoothGattException("Test", 133)))
+                .isFalse();
+        assertThat(
+                GattConnectionManager.isNoRetryError(
+                        preferences, new BluetoothGattException("Test", 257)))
+                .isTrue();
+        assertThat(
+                GattConnectionManager.isNoRetryError(
+                        preferences, new BluetoothGattException("Test", 999)))
+                .isTrue();
+        assertThat(GattConnectionManager.isNoRetryError(
+                preferences, new BluetoothException("Test")))
+                .isFalse();
+        assertThat(
+                GattConnectionManager.isNoRetryError(
+                        preferences, new BluetoothOperationTimeoutException("Test")))
+                .isFalse();
+    }
+
+    @SdkSuppress(minSdkVersion = 32, codeName = "T")
+    public void testGetTimeoutNotOverShortRetryMaxSpentTimeGetShort() {
+        Preferences preferences = Preferences.builder().build();
+
+        assertThat(
+                createManager(Preferences.builder(), () -> {})
+                        .getTimeoutMs(
+                                preferences.getGattConnectShortTimeoutRetryMaxSpentTimeMs() - 1))
+                .isEqualTo(preferences.getGattConnectShortTimeoutMs());
+    }
+
+    @SdkSuppress(minSdkVersion = 32, codeName = "T")
+    public void testGetTimeoutOverShortRetryMaxSpentTimeGetLong() {
+        Preferences preferences = Preferences.builder().build();
+
+        assertThat(
+                createManager(Preferences.builder(), () -> {})
+                        .getTimeoutMs(
+                                preferences.getGattConnectShortTimeoutRetryMaxSpentTimeMs() + 1))
+                .isEqualTo(preferences.getGattConnectLongTimeoutMs());
+    }
+
+    @SdkSuppress(minSdkVersion = 32, codeName = "T")
+    public void testGetTimeoutRetryNotEnabledGetOrigin() {
+        Preferences preferences = Preferences.builder().build();
+
+        assertThat(
+                createManager(
+                        Preferences.builder().setRetryGattConnectionAndSecretHandshake(false),
+                        () -> {})
+                        .getTimeoutMs(0))
+                .isEqualTo(Duration.ofSeconds(
+                        preferences.getGattConnectionTimeoutSeconds()).toMillis());
+    }
+
+    private GattConnectionManager createManager(Preferences.Builder prefs) {
+        return createManager(prefs, () -> {});
+    }
+
+    private GattConnectionManager createManager(
+            Preferences.Builder prefs, ToggleBluetoothTask toggleBluetooth) {
+        return createManager(prefs, toggleBluetooth,
+                /* fastPairSignalChecker= */ null);
+    }
+
+    private GattConnectionManager createManager(
+            Preferences.Builder prefs,
+            ToggleBluetoothTask toggleBluetooth,
+            @Nullable FastPairConnection.FastPairSignalChecker fastPairSignalChecker) {
+        return new GattConnectionManager(
+                ApplicationProvider.getApplicationContext(),
+                prefs.build(),
+                new EventLoggerWrapper(null),
+                BluetoothAdapter.getDefaultAdapter(),
+                toggleBluetooth,
+                FAST_PAIR_ADDRESS,
+                new TimingLogger("GattConnectionManager", prefs.build()),
+                fastPairSignalChecker,
+                /* setMtu= */ false);
+    }
+}
diff --git a/nearby/tests/unit/src/com/android/server/nearby/provider/BleDiscoveryProviderTest.java b/nearby/tests/unit/src/com/android/server/nearby/provider/BleDiscoveryProviderTest.java
new file mode 100644
index 0000000..4c78885
--- /dev/null
+++ b/nearby/tests/unit/src/com/android/server/nearby/provider/BleDiscoveryProviderTest.java
@@ -0,0 +1,116 @@
+/*
+ * 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.server.nearby.provider;
+
+import static android.bluetooth.le.ScanSettings.CALLBACK_TYPE_ALL_MATCHES;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.MockitoAnnotations.initMocks;
+
+import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.BluetoothDevice;
+import android.bluetooth.BluetoothManager;
+import android.bluetooth.le.ScanRecord;
+import android.bluetooth.le.ScanResult;
+import android.content.Context;
+
+import androidx.test.platform.app.InstrumentationRegistry;
+
+import com.android.server.nearby.injector.Injector;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+public final class BleDiscoveryProviderTest {
+
+    private BluetoothAdapter mBluetoothAdapter;
+    private BleDiscoveryProvider mBleDiscoveryProvider;
+    @Mock
+    private AbstractDiscoveryProvider.Listener mListener;
+
+    @Before
+    public void setup() {
+        initMocks(this);
+        Context context = InstrumentationRegistry.getInstrumentation().getContext();
+        Injector injector = new TestInjector();
+
+        mBluetoothAdapter = context.getSystemService(BluetoothManager.class).getAdapter();
+        mBleDiscoveryProvider = new BleDiscoveryProvider(context, injector);
+    }
+
+    @Test
+    public void test_callback() throws InterruptedException {
+        mBleDiscoveryProvider.getController().setListener(mListener);
+        mBleDiscoveryProvider.onStart();
+        mBleDiscoveryProvider.getScanCallback()
+                .onScanResult(CALLBACK_TYPE_ALL_MATCHES, createScanResult());
+
+        // Wait for callback to be invoked
+        Thread.sleep(500);
+        verify(mListener, times(1)).onNearbyDeviceDiscovered(any());
+    }
+
+    @Test
+    public void test_stopScan() {
+        mBleDiscoveryProvider.onStart();
+        mBleDiscoveryProvider.onStop();
+    }
+
+    private class TestInjector implements Injector {
+        @Override
+        public BluetoothAdapter getBluetoothAdapter() {
+            return mBluetoothAdapter;
+        }
+    }
+
+    private ScanResult createScanResult() {
+        BluetoothDevice bluetoothDevice = mBluetoothAdapter
+                .getRemoteDevice("11:22:33:44:55:66");
+        byte[] scanRecord = new byte[] {2, 1, 6, 6, 22, 44, -2, 113, -116, 23, 2, 10, -11, 0, 0, 0,
+                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+        return new ScanResult(
+                bluetoothDevice,
+                /* eventType= */ 0,
+                /* primaryPhy= */ 0,
+                /* secondaryPhy= */ 0,
+                /* advertisingSid= */ 0,
+                -31,
+                -50,
+                /* periodicAdvertisingInterval= */ 0,
+                parseScanRecord(scanRecord),
+                1645579363003L);
+    }
+
+    private static ScanRecord parseScanRecord(byte[] bytes) {
+        Class<?> scanRecordClass = ScanRecord.class;
+        try {
+            Method method = scanRecordClass
+                    .getDeclaredMethod("parseFromBytes", byte[].class);
+            return (ScanRecord) method.invoke(null, bytes);
+        } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException
+                | InvocationTargetException e) {
+            return null;
+        }
+    }
+}