diff --git a/libs/user/domain/src/index.ts b/libs/user/domain/src/index.ts
index 2dbc61e..9602d75 100644
--- a/libs/user/domain/src/index.ts
+++ b/libs/user/domain/src/index.ts
@@ -1 +1,3 @@
+// user
 export * from './lib/user.entity';
+export * from './lib/user.repository';
diff --git a/libs/user/domain/src/lib/user.repository.spec.ts b/libs/user/domain/src/lib/user.repository.spec.ts
new file mode 100644
index 0000000..b8d7397
--- /dev/null
+++ b/libs/user/domain/src/lib/user.repository.spec.ts
@@ -0,0 +1,43 @@
+import { UserRepository } from './user.repository';
+import { User } from './user.entity';
+
+class MockUserRepository implements UserRepository {
+  private users: User[] = [
+    { id: '1', name: 'John Doe' },
+    { id: '2', name: 'Jane Doe' },
+  ];
+
+  async findById(id: string): Promise<User | null> {
+    return this.users.find((user) => user.id === id) || null;
+  }
+
+  async findAll(): Promise<User[]> {
+    return this.users;
+  }
+}
+
+describe('UserRepository', () => {
+  let userRepository: UserRepository;
+
+  beforeEach(() => {
+    userRepository = new MockUserRepository();
+  });
+
+  test('findById should return a user by id', async () => {
+    const user = await userRepository.findById('1');
+    expect(user).toEqual({ id: '1', name: 'John Doe' });
+  });
+
+  test('findById should return null if user not found', async () => {
+    const user = await userRepository.findById('3');
+    expect(user).toBeNull();
+  });
+
+  test('findAll should return all users', async () => {
+    const users = await userRepository.findAll();
+    expect(users).toEqual([
+      { id: '1', name: 'John Doe' },
+      { id: '2', name: 'Jane Doe' },
+    ]);
+  });
+});
diff --git a/libs/user/domain/src/lib/user.repository.ts b/libs/user/domain/src/lib/user.repository.ts
new file mode 100644
index 0000000..45e63c9
--- /dev/null
+++ b/libs/user/domain/src/lib/user.repository.ts
@@ -0,0 +1,6 @@
+import { User } from './user.entity';
+
+export interface UserRepository {
+  findById(id: string): Promise<User | null>;
+  findAll(): Promise<User[]>;
+}
\ No newline at end of file