diff --git a/app/src/test/java/com/d4rk/androidtutorials/java/notifications/managers/AppUsageNotificationsManagerTest.java b/app/src/test/java/com/d4rk/androidtutorials/java/notifications/managers/AppUsageNotificationsManagerTest.java
new file mode 100644
index 00000000..f7dcfd4a
--- /dev/null
+++ b/app/src/test/java/com/d4rk/androidtutorials/java/notifications/managers/AppUsageNotificationsManagerTest.java
@@ -0,0 +1,48 @@
+package com.d4rk.androidtutorials.java.notifications.managers;
+
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.app.AlarmManager;
+import android.app.PendingIntent;
+import android.content.Context;
+
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Tests for {@link AppUsageNotificationsManager}.
+ */
+public class AppUsageNotificationsManagerTest {
+
+    @Test
+    public void scheduleAppUsageCheck_setsRepeatingAlarmWithThreeDayInterval() {
+        AlarmManager alarmManager = mock(AlarmManager.class);
+        Context context = mock(Context.class);
+        when(context.getSystemService(Context.ALARM_SERVICE)).thenReturn(alarmManager);
+        when(context.getApplicationContext()).thenReturn(context);
+
+        long now = System.currentTimeMillis();
+        AppUsageNotificationsManager manager = new AppUsageNotificationsManager(context);
+
+        manager.scheduleAppUsageCheck();
+
+        ArgumentCaptor<Long> triggerCaptor = ArgumentCaptor.forClass(Long.class);
+        verify(alarmManager).setRepeating(
+                eq(AlarmManager.RTC_WAKEUP),
+                triggerCaptor.capture(),
+                eq(TimeUnit.DAYS.toMillis(3)),
+                any(PendingIntent.class)
+        );
+
+        long expectedTrigger = now + TimeUnit.DAYS.toMillis(3);
+        assertTrue(Math.abs(triggerCaptor.getValue() - expectedTrigger) < 1000);
+    }
+}
+
diff --git a/app/src/test/java/com/d4rk/androidtutorials/java/notifications/workers/AppUsageNotificationWorkerTest.java b/app/src/test/java/com/d4rk/androidtutorials/java/notifications/workers/AppUsageNotificationWorkerTest.java
new file mode 100644
index 00000000..f59aff4a
--- /dev/null
+++ b/app/src/test/java/com/d4rk/androidtutorials/java/notifications/workers/AppUsageNotificationWorkerTest.java
@@ -0,0 +1,102 @@
+package com.d4rk.androidtutorials.java.notifications.workers;
+
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockConstruction;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import androidx.preference.PreferenceManager;
+import androidx.work.WorkerParameters;
+
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.MockedConstruction;
+import org.mockito.MockedStatic;
+
+/**
+ * Tests for {@link AppUsageNotificationWorker}.
+ */
+public class AppUsageNotificationWorkerTest {
+
+    @Test
+    public void doWork_lastUsedExceedsThreshold_showsNotificationAndUpdatesTimestamp() {
+        Context context = mock(Context.class);
+        when(context.getApplicationContext()).thenReturn(context);
+        when(context.getString(anyInt())).thenReturn("");
+        NotificationManager notificationManager = mock(NotificationManager.class);
+        when(context.getSystemService(Context.NOTIFICATION_SERVICE)).thenReturn(notificationManager);
+
+        SharedPreferences sharedPreferences = mock(SharedPreferences.class);
+        SharedPreferences.Editor editor = mock(SharedPreferences.Editor.class);
+        when(sharedPreferences.getLong(eq("lastUsed"), anyLong())).thenReturn(0L);
+        when(sharedPreferences.edit()).thenReturn(editor);
+        when(editor.putLong(anyString(), anyLong())).thenReturn(editor);
+
+        try (MockedStatic<PreferenceManager> prefManager = mockStatic(PreferenceManager.class);
+             MockedConstruction<NotificationChannel> ignoredChannel = mockConstruction(NotificationChannel.class)) {
+            prefManager.when(() -> PreferenceManager.getDefaultSharedPreferences(context))
+                    .thenReturn(sharedPreferences);
+
+            WorkerParameters workerParameters = mock(WorkerParameters.class);
+            AppUsageNotificationWorker worker = new AppUsageNotificationWorker(context, workerParameters);
+
+            worker.doWork();
+        }
+
+        verify(notificationManager, times(1)).notify(eq(0), any(Notification.class));
+
+        ArgumentCaptor<Long> captor = ArgumentCaptor.forClass(Long.class);
+        verify(editor).putLong(eq("lastUsed"), captor.capture());
+        verify(editor).apply();
+        assertTrue(captor.getValue() > 0L);
+    }
+
+    @Test
+    public void doWork_lastUsedWithinThreshold_noNotificationButTimestampUpdated() {
+        Context context = mock(Context.class);
+        when(context.getApplicationContext()).thenReturn(context);
+        when(context.getString(anyInt())).thenReturn("");
+        NotificationManager notificationManager = mock(NotificationManager.class);
+        when(context.getSystemService(Context.NOTIFICATION_SERVICE)).thenReturn(notificationManager);
+
+        long lastUsed = System.currentTimeMillis();
+        SharedPreferences sharedPreferences = mock(SharedPreferences.class);
+        SharedPreferences.Editor editor = mock(SharedPreferences.Editor.class);
+        when(sharedPreferences.getLong(eq("lastUsed"), anyLong())).thenReturn(lastUsed);
+        when(sharedPreferences.edit()).thenReturn(editor);
+        when(editor.putLong(anyString(), anyLong())).thenReturn(editor);
+
+        try (MockedStatic<PreferenceManager> prefManager = mockStatic(PreferenceManager.class);
+             MockedConstruction<NotificationChannel> ignoredChannel = mockConstruction(NotificationChannel.class)) {
+            prefManager.when(() -> PreferenceManager.getDefaultSharedPreferences(context))
+                    .thenReturn(sharedPreferences);
+
+            WorkerParameters workerParameters = mock(WorkerParameters.class);
+            AppUsageNotificationWorker worker = new AppUsageNotificationWorker(context, workerParameters);
+
+            worker.doWork();
+        }
+
+        verify(notificationManager, never()).notify(anyInt(), any(Notification.class));
+
+        ArgumentCaptor<Long> captor = ArgumentCaptor.forClass(Long.class);
+        verify(editor).putLong(eq("lastUsed"), captor.capture());
+        verify(editor).apply();
+        assertTrue(captor.getValue() >= lastUsed);
+    }
+}
+