diff --git a/__mocks__/react-native.ts b/__mocks__/react-native.ts
index 3c6670b6..517f1d10 100644
--- a/__mocks__/react-native.ts
+++ b/__mocks__/react-native.ts
@@ -85,6 +85,7 @@ const mockRNOneSignal = {
   addUniqueOutcome: vi.fn(),
   addOutcomeWithValue: vi.fn(),
   displayNotification: vi.fn(),
+  preventDefault: vi.fn(),
 };
 
 const mockPlatform = {
diff --git a/src/events/NotificationWillDisplayEvent.test.ts b/src/events/NotificationWillDisplayEvent.test.ts
new file mode 100644
index 00000000..217ffb83
--- /dev/null
+++ b/src/events/NotificationWillDisplayEvent.test.ts
@@ -0,0 +1,107 @@
+import { NativeModules } from 'react-native';
+import OSNotification, { type BaseNotificationData } from '../OSNotification';
+import NotificationWillDisplayEvent from './NotificationWillDisplayEvent';
+
+const mockRNOneSignal = NativeModules.OneSignal;
+
+describe('NotificationWillDisplayEvent', () => {
+  const notificationId = 'test-notification-id';
+  const baseNotificationData: BaseNotificationData = {
+    body: 'Test notification body',
+    sound: 'default',
+    title: 'Test Title',
+    launchURL: 'https://example.com',
+    rawPayload: { key: 'value' },
+    actionButtons: [{ id: 'btn1', text: 'Button 1' }],
+    additionalData: { custom: 'data' },
+    notificationId,
+  };
+
+  describe('constructor', () => {
+    test('should initialize with OSNotification instance', () => {
+      const notification = new OSNotification(baseNotificationData);
+      const event = new NotificationWillDisplayEvent(notification);
+
+      expect(event.notification).toBeInstanceOf(OSNotification);
+      expect(event.notification.notificationId).toBe(notificationId);
+      expect(event.notification.body).toBe('Test notification body');
+      expect(event.notification.title).toBe('Test Title');
+    });
+
+    test('should create a new OSNotification instance from the provided notification', () => {
+      const notification = new OSNotification(baseNotificationData);
+      const event = new NotificationWillDisplayEvent(notification);
+
+      expect(event.notification).not.toBe(notification);
+      expect(event.notification.notificationId).toBe(notificationId);
+      expect(event.notification.body).toBe(notification.body);
+    });
+
+    test('should initialize with notification containing all optional fields', () => {
+      const fullData = {
+        ...baseNotificationData,
+        sound: 'custom-sound',
+        launchURL: 'https://example.com/launch',
+        actionButtons: [
+          { id: 'btn1', text: 'Button 1' },
+          { id: 'btn2', text: 'Button 2' },
+        ],
+        additionalData: { key1: 'value1', key2: 'value2' },
+      };
+      const notification = new OSNotification(fullData);
+      const event = new NotificationWillDisplayEvent(notification);
+
+      expect(event.notification.sound).toBe('custom-sound');
+      expect(event.notification.launchURL).toBe('https://example.com/launch');
+      expect(event.notification.actionButtons).toHaveLength(2);
+      expect(event.notification.additionalData).toEqual({
+        key1: 'value1',
+        key2: 'value2',
+      });
+    });
+  });
+
+  describe('preventDefault', () => {
+    test('should call native preventDefault with notificationId', () => {
+      const notification = new OSNotification(baseNotificationData);
+      const event = new NotificationWillDisplayEvent(notification);
+      const result = event.preventDefault();
+
+      expect(mockRNOneSignal.preventDefault).toHaveBeenCalledWith(
+        notificationId,
+      );
+      expect(result).toBeUndefined();
+    });
+
+    test('should allow multiple calls to preventDefault', () => {
+      const notification = new OSNotification(baseNotificationData);
+      const event = new NotificationWillDisplayEvent(notification);
+
+      event.preventDefault();
+      event.preventDefault();
+      event.preventDefault();
+
+      expect(mockRNOneSignal.preventDefault).toHaveBeenCalledTimes(3);
+      expect(mockRNOneSignal.preventDefault).toHaveBeenCalledWith(
+        'test-notification-id',
+      );
+    });
+  });
+
+  describe('getNotification', () => {
+    test('should return the notification instance', () => {
+      const notification = new OSNotification(baseNotificationData);
+      const event = new NotificationWillDisplayEvent(notification);
+      const returnedNotification = event.getNotification();
+
+      expect(returnedNotification).toBe(event.notification);
+      expect(returnedNotification).toBeInstanceOf(OSNotification);
+
+      expect(returnedNotification.notificationId).toBe('test-notification-id');
+      expect(returnedNotification.body).toBe('Test notification body');
+      expect(returnedNotification.title).toBe('Test Title');
+      expect(returnedNotification.sound).toBe('default');
+      expect(returnedNotification.rawPayload).toEqual({ key: 'value' });
+    });
+  });
+});
diff --git a/src/events/NotificationWillDisplayEvent.ts b/src/events/NotificationWillDisplayEvent.ts
index e647aba9..c042b5df 100644
--- a/src/events/NotificationWillDisplayEvent.ts
+++ b/src/events/NotificationWillDisplayEvent.ts
@@ -11,7 +11,6 @@ export default class NotificationWillDisplayEvent {
 
   preventDefault(): void {
     RNOneSignal.preventDefault(this.notification.notificationId);
-    return;
   }
 
   getNotification(): OSNotification {
diff --git a/src/helpers.test.ts b/src/helpers.test.ts
new file mode 100644
index 00000000..b3e5fb6c
--- /dev/null
+++ b/src/helpers.test.ts
@@ -0,0 +1,61 @@
+import type { NativeModule } from 'react-native';
+import type { MockInstance } from 'vitest';
+import { isNativeModuleLoaded, isValidCallback } from './helpers';
+
+describe('helpers', () => {
+  let errorSpy: MockInstance;
+
+  beforeEach(() => {
+    errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+  });
+
+  describe('isValidCallback', () => {
+    test('should not throw when handler is a function', () => {
+      const handler = () => {};
+      expect(() => isValidCallback(handler)).not.toThrow();
+    });
+
+    test.each([
+      { description: 'null', value: null },
+      { description: 'undefined', value: undefined },
+      { description: 'a string', value: 'not a function' },
+      { description: 'a number', value: 123 },
+      { description: 'an object', value: {} },
+      { description: 'an array', value: [] },
+      { description: 'a boolean', value: true },
+    ])(
+      'should throw invariant error when handler is $description',
+      ({ value }) => {
+        expect(() => isValidCallback(value as unknown as Function)).toThrow(
+          'Must provide a valid callback',
+        );
+      },
+    );
+  });
+
+  describe('isNativeModuleLoaded', () => {
+    test.each([
+      { description: 'null', value: null as unknown as NativeModule },
+      {
+        description: 'undefined',
+        value: undefined as unknown as NativeModule,
+      },
+    ])(
+      'should return false and log error when module is $description',
+      ({ value }) => {
+        const result = isNativeModuleLoaded(value);
+
+        expect(result).toBe(false);
+        expect(errorSpy).toHaveBeenCalledTimes(1);
+        expect(errorSpy).toHaveBeenCalledWith(
+          'Could not load RNOneSignal native module. Make sure native dependencies are properly linked.',
+        );
+      },
+    );
+
+    test('should return true when module is loaded', () => {
+      const result = isNativeModuleLoaded({} as NativeModule);
+      expect(result).toBe(true);
+    });
+  });
+});
diff --git a/vitest.config.ts b/vitest.config.ts
index 26641578..097c3aa8 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -13,6 +13,12 @@ export default defineConfig({
       reporter: ['text-summary', 'lcov'],
       reportOnFailure: true,
       reportsDirectory: 'coverage',
+      thresholds: {
+        statements: 95,
+        branches: 95,
+        functions: 95,
+        lines: 95,
+      },
     },
   },
   resolve: {