diff --git a/src/com/android/phone/NotificationMgr.java b/src/com/android/phone/NotificationMgr.java
index f2641a1..b9d1f53 100644
--- a/src/com/android/phone/NotificationMgr.java
+++ b/src/com/android/phone/NotificationMgr.java
@@ -57,6 +57,7 @@
 import android.util.SparseArray;
 import android.widget.Toast;
 
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.telephony.Phone;
 import com.android.internal.telephony.PhoneFactory;
 import com.android.internal.telephony.TelephonyCapabilities;
@@ -163,7 +164,8 @@
      * Private constructor (this is a singleton).
      * @see #init(PhoneGlobals)
      */
-    private NotificationMgr(PhoneGlobals app) {
+    @VisibleForTesting
+    /* package */ NotificationMgr(PhoneGlobals app) {
         mApp = app;
         mContext = app;
         mStatusBarManager =
diff --git a/tests/src/com/android/phone/NotificationMgrTest.java b/tests/src/com/android/phone/NotificationMgrTest.java
new file mode 100644
index 0000000..8a63e54
--- /dev/null
+++ b/tests/src/com/android/phone/NotificationMgrTest.java
@@ -0,0 +1,344 @@
+/*
+ * 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.phone;
+
+import static com.android.phone.NotificationMgr.DATA_ROAMING_NOTIFICATION;
+import static com.android.phone.NotificationMgr.LIMITED_SIM_FUNCTION_NOTIFICATION;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.anyString;
+import static org.mockito.Mockito.eq;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.app.Notification;
+import android.app.NotificationManager;
+import android.app.StatusBarManager;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.pm.ApplicationInfo;
+import android.content.res.Resources;
+import android.os.Build;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.telecom.TelecomManager;
+import android.telephony.ServiceState;
+import android.telephony.SubscriptionInfo;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyManager;
+import android.testing.AndroidTestingRunner;
+import android.testing.TestableLooper;
+
+import com.android.internal.telephony.Phone;
+import com.android.internal.telephony.PhoneConstants;
+import com.android.internal.telephony.PhoneFactory;
+import com.android.internal.telephony.util.NotificationChannelController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.lang.reflect.Field;
+
+/**
+ * Unit Test for NotificationMgr
+ */
+@RunWith(AndroidTestingRunner.class)
+@TestableLooper.RunWithLooper
+public class NotificationMgrTest {
+
+    private static final int TEST_SUB_ID = 1;
+    private static final long SERIAL_NUMBER_OF_USER = 1234567L;
+    private static final String TEST_LABEL_CF = "test_call_forwarding";
+    private static final String TEST_SUB_INFO_DISPLAY_NAME = "display_name";
+    private static final String TEST_PACKAGE_NAME = "com.android.phone";
+    private static final String TEST_SELECTED_NETWORK_OPERATOR_NAME = "TheOperator";
+    private static final String MOBILE_NETWORK_SELECTION_PACKAGE = "com.android.phone";
+    private static final String MOBILE_NETWORK_SELECTION_CLASS = ".testClass";
+    private static final String CARRIER_NAME = "CoolCarrier";
+
+    @Mock PhoneGlobals mApp;
+    @Mock StatusBarManager mStatusBarManager;
+    @Mock UserManager mUserManager;
+    @Mock SubscriptionManager mSubscriptionManager;
+    @Mock TelecomManager mTelecomManager;
+    @Mock TelephonyManager mTelephonyManager;
+    @Mock Phone mPhone;
+    @Mock SharedPreferences mSharedPreferences;
+    @Mock NotificationManager mNotificationManager;
+    @Mock SubscriptionInfo mSubscriptionInfo;
+    @Mock Resources mResources;
+    @Mock ServiceState mServiceState;
+
+    private Phone[] mPhones;
+    private NotificationMgr mNotificationMgr;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        mPhones = new Phone[]{mPhone};
+        replaceInstance(PhoneFactory.class, "sPhones", null, mPhones);
+        when(mPhone.getPhoneType()).thenReturn(PhoneConstants.PHONE_TYPE_GSM);
+        when(mApp.getSharedPreferences(anyString(), anyInt())).thenReturn(mSharedPreferences);
+
+        when(mApp.getPackageName()).thenReturn(TEST_PACKAGE_NAME);
+        when(mApp.getSystemService(Context.STATUS_BAR_SERVICE)).thenReturn(mStatusBarManager);
+        when(mApp.getSystemService(Context.USER_SERVICE)).thenReturn(mUserManager);
+        when(mApp.getSystemService(Context.TELEPHONY_SUBSCRIPTION_SERVICE)).thenReturn(
+                mSubscriptionManager);
+        when(mApp.getSystemServiceName(TelecomManager.class)).thenReturn(Context.TELECOM_SERVICE);
+        when(mApp.getSystemService(TelecomManager.class)).thenReturn(mTelecomManager);
+        when(mApp.getSystemService(Context.TELEPHONY_SERVICE)).thenReturn(mTelephonyManager);
+
+        when(mApp.createPackageContextAsUser(any(), eq(0), any())).thenReturn(mApp);
+        when(mApp.getSystemService(Context.NOTIFICATION_SERVICE)).thenReturn(mNotificationManager);
+        when(mUserManager.getSerialNumbersOfUsers(true)).thenReturn(
+                new long[]{SERIAL_NUMBER_OF_USER});
+        when(mUserManager.getUserForSerialNumber(eq(SERIAL_NUMBER_OF_USER))).thenReturn(
+                UserHandle.SYSTEM);
+        when(mApp.getResources()).thenReturn(mResources);
+        when(mResources.getString(R.string.labelCF)).thenReturn(TEST_LABEL_CF);
+        ApplicationInfo appWithSdkS = buildApplicationInfo(Build.VERSION_CODES.S);
+        when(mApp.getApplicationInfo()).thenReturn(appWithSdkS);
+        when(mTelephonyManager.createForSubscriptionId(anyInt())).thenReturn(mTelephonyManager);
+        when(mTelephonyManager.getServiceState()).thenReturn(mServiceState);
+
+        mNotificationMgr = new NotificationMgr(mApp);
+    }
+
+    @Test
+    public void testUpdateCfi_visible_noActiveSubscription_notificationNeverSent()
+            throws Exception {
+        // Given no active subscription available
+        when(mSubscriptionManager.getActiveSubscriptionInfo(eq(TEST_SUB_ID))).thenReturn(null);
+
+        // When updateCfi method is called
+        mNotificationMgr.updateCfi(TEST_SUB_ID, /*visible=*/true, /*isFresh=*/false);
+
+        // Then the notification should never be sent
+        verify(mNotificationManager, never()).notify(any(), anyInt(), any());
+    }
+
+    @Test
+    public void testUpdateCfi_visible_hasActiveSub_singleSIM_notificationSent()
+            throws Exception {
+        when(mTelephonyManager.getPhoneCount()).thenReturn(1);
+        when(mSubscriptionManager.getActiveSubscriptionInfo(eq(TEST_SUB_ID))).thenReturn(
+                mSubscriptionInfo);
+
+        mNotificationMgr.updateCfi(TEST_SUB_ID, /*visible=*/true, /*isFresh=*/false);
+
+        verifyNotificationSentWithChannelId(NotificationChannelController.CHANNEL_ID_CALL_FORWARD);
+    }
+
+    @Test
+    public void testUpdateCfi_visible_hasActiveSub_multiSIM_notificationSentWithoutDisplayName()
+            throws Exception {
+        when(mTelephonyManager.getPhoneCount()).thenReturn(2);
+        when(mSubscriptionManager.getActiveSubscriptionInfo(eq(TEST_SUB_ID))).thenReturn(
+                mSubscriptionInfo);
+        when(mSubscriptionInfo.getDisplayName()).thenReturn(null);
+
+        mNotificationMgr.updateCfi(TEST_SUB_ID, /*visible=*/true, /*isFresh=*/false);
+
+        verifyNotificationSentWithChannelId(NotificationChannelController.CHANNEL_ID_CALL_FORWARD);
+    }
+
+    @Test
+    public void testUpdateCfi_visible_hasActiveSub_multiSIM_notificationSentWithDisplayName()
+            throws Exception {
+        when(mTelephonyManager.getPhoneCount()).thenReturn(2);
+        when(mSubscriptionManager.getActiveSubscriptionInfo(eq(TEST_SUB_ID))).thenReturn(
+                mSubscriptionInfo);
+        when(mSubscriptionInfo.getDisplayName()).thenReturn(TEST_SUB_INFO_DISPLAY_NAME);
+
+        mNotificationMgr.updateCfi(TEST_SUB_ID, /*visible=*/true, /*isFresh=*/false);
+
+        verifyNotificationSentWithChannelId(NotificationChannelController.CHANNEL_ID_CALL_FORWARD);
+    }
+
+    @Test
+    public void testUpdateCfi_invisible_hasUnmanagedProfile_notificationCanceled()
+            throws Exception {
+        when(mUserManager.isManagedProfile(anyInt())).thenReturn(false);
+
+        mNotificationMgr.updateCfi(TEST_SUB_ID, /*visible=*/false, /*isFresh=*/false);
+
+        verify(mNotificationManager).cancel(any(), anyInt());
+    }
+
+    @Test
+    public void testUpdateCfi_invisible_allProfilesAreManaged_notificationNeverCanceled()
+            throws Exception {
+        when(mUserManager.isManagedProfile(anyInt())).thenReturn(true);
+
+        mNotificationMgr.updateCfi(TEST_SUB_ID, /*visible=*/false, /*isFresh=*/false);
+
+        verify(mNotificationManager, never()).cancel(any(), anyInt());
+    }
+
+    @Test
+    public void testShowDataRoamingNotification_roamingOn() throws Exception {
+        mNotificationMgr.showDataRoamingNotification(TEST_SUB_ID, /*roamingOn=*/true);
+
+        verifyNotificationSentWithChannelId(
+                NotificationChannelController.CHANNEL_ID_MOBILE_DATA_STATUS);
+    }
+
+    @Test
+    public void testShowDataRoamingNotification_roamingOff() throws Exception {
+        mNotificationMgr.showDataRoamingNotification(TEST_SUB_ID, /*roamingOn=*/false);
+
+        verifyNotificationSentWithChannelId(
+                NotificationChannelController.CHANNEL_ID_MOBILE_DATA_STATUS);
+    }
+
+    @Test
+    public void testHideDataRoamingNotification() {
+        mNotificationMgr.hideDataRoamingNotification();
+
+        verify(mNotificationManager).cancel(any(), eq(DATA_ROAMING_NOTIFICATION));
+    }
+
+    @Test
+    public void testUpdateNetworkSelection_justOutOfService_notificationNeverSent()
+            throws Exception {
+        prepareResourcesForNetworkSelection();
+
+        mNotificationMgr.updateNetworkSelection(ServiceState.STATE_OUT_OF_SERVICE, TEST_SUB_ID);
+        try {
+            Thread.sleep(2000);
+        } catch (InterruptedException ignored) {
+        }
+
+        verify(mNotificationManager, never()).notify(any(), anyInt(), any());
+    }
+
+    @Test
+    public void testUpdateNetworkSelection_outOfServiceForEnoughTime_notificationSent()
+            throws Exception {
+        prepareResourcesForNetworkSelection();
+
+        mNotificationMgr.updateNetworkSelection(ServiceState.STATE_OUT_OF_SERVICE, TEST_SUB_ID);
+        // TODO: use effective TestLooper time eclipse instead of sleeping
+        try {
+            Thread.sleep(10000);
+        } catch (InterruptedException ignored) {
+        }
+        mNotificationMgr.updateNetworkSelection(ServiceState.STATE_OUT_OF_SERVICE, TEST_SUB_ID);
+
+        verifyNotificationSentWithChannelId(NotificationChannelController.CHANNEL_ID_ALERT);
+    }
+
+    @Test
+    public void testShowLimitedSimFunctionWarningNotification_forTheFirstTime_notificationSent()
+            throws Exception {
+        when(mResources.getText(R.string.limited_sim_function_notification_message)).thenReturn(
+                CARRIER_NAME);
+        when(mResources.getText(
+                R.string.limited_sim_function_with_phone_num_notification_message)).thenReturn(
+                "123");
+
+        mNotificationMgr.showLimitedSimFunctionWarningNotification(TEST_SUB_ID, CARRIER_NAME);
+
+        verifyNotificationSentWithChannelId(
+                NotificationChannelController.CHANNEL_ID_SIM_HIGH_PRIORITY);
+    }
+
+    @Test
+    public void testShowLimitedSimFunctionWarningNotification_consecutiveCall_notificationSentOnce()
+            throws Exception {
+        when(mResources.getText(R.string.limited_sim_function_notification_message)).thenReturn(
+                CARRIER_NAME);
+        when(mResources.getText(
+                R.string.limited_sim_function_with_phone_num_notification_message)).thenReturn(
+                "123");
+
+        // Call the method TWICE with the same subscription
+        mNotificationMgr.showLimitedSimFunctionWarningNotification(TEST_SUB_ID, CARRIER_NAME);
+        mNotificationMgr.showLimitedSimFunctionWarningNotification(TEST_SUB_ID, CARRIER_NAME);
+
+        // Verify the notification is only sent ONCE
+        verifyNotificationSentWithChannelId(
+                NotificationChannelController.CHANNEL_ID_SIM_HIGH_PRIORITY);
+    }
+
+    @Test
+    public void testDismissLimitedSimFunctionWarningNotification_noShowCalledBefore_noCancelSent()
+            throws Exception {
+        // showLimitedSimFunctionWarningNotification was never called before
+
+        mNotificationMgr.dismissLimitedSimFunctionWarningNotification(TEST_SUB_ID);
+
+        verify(mNotificationManager, never()).cancel(any(), anyInt());
+    }
+
+    @Test
+    public void testDismissLimitedSimFunctionWarningNotification_showCalledBefore_cancelSent()
+            throws Exception {
+        when(mResources.getText(R.string.limited_sim_function_notification_message)).thenReturn(
+                CARRIER_NAME);
+        when(mResources.getText(
+                R.string.limited_sim_function_with_phone_num_notification_message)).thenReturn(
+                "123");
+        mNotificationMgr.showLimitedSimFunctionWarningNotification(TEST_SUB_ID, CARRIER_NAME);
+
+        mNotificationMgr.dismissLimitedSimFunctionWarningNotification(TEST_SUB_ID);
+
+        verify(mNotificationManager).cancel(any(), eq(LIMITED_SIM_FUNCTION_NOTIFICATION));
+    }
+
+    private ApplicationInfo buildApplicationInfo(int targetSdkVersion) {
+        ApplicationInfo applicationInfo = new ApplicationInfo();
+        applicationInfo.targetSdkVersion = targetSdkVersion;
+        return applicationInfo;
+    }
+
+    private void verifyNotificationSentWithChannelId(String expectedNotificationChannelId) {
+        ArgumentCaptor<Notification> notificationArgumentCaptor = ArgumentCaptor.forClass(
+                Notification.class);
+        verify(mNotificationManager).notify(any(), anyInt(), notificationArgumentCaptor.capture());
+        Notification capturedNotification = notificationArgumentCaptor.getAllValues().get(0);
+        assertThat(capturedNotification.getChannelId()).isEqualTo(expectedNotificationChannelId);
+    }
+
+    private void prepareResourcesForNetworkSelection() {
+        when(mSharedPreferences.getString(Phone.NETWORK_SELECTION_NAME_KEY + TEST_SUB_ID,
+                "")).thenReturn(TEST_SELECTED_NETWORK_OPERATOR_NAME);
+        when(mResources.getBoolean(
+                com.android.internal.R.bool.skip_restoring_network_selection)).thenReturn(false);
+        when(mServiceState.getState()).thenReturn(ServiceState.STATE_OUT_OF_SERVICE);
+        when(mApp.getString(R.string.mobile_network_settings_package)).thenReturn(
+                MOBILE_NETWORK_SELECTION_PACKAGE);
+        when(mApp.getString(R.string.mobile_network_settings_class)).thenReturn(
+                MOBILE_NETWORK_SELECTION_CLASS);
+    }
+
+    private static void replaceInstance(final Class c,
+            final String instanceName, final Object obj, final Object newValue) throws Exception {
+        Field field = c.getDeclaredField(instanceName);
+        field.setAccessible(true);
+        field.set(obj, newValue);
+    }
+}