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/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);
+    }
+}