diff --git a/src/modules/authentication/core/domain/username.entity.ts b/src/modules/authentication/core/domain/username.entity.ts
index 5fd83fa..d00806e 100644
--- a/src/modules/authentication/core/domain/username.entity.ts
+++ b/src/modules/authentication/core/domain/username.entity.ts
@@ -1,11 +1,13 @@
 import { AggregateID, AggregateRoot } from '@mobicoop/ddd-library';
-import { UsernameProps } from './username.types';
+import { CreateUsernameProps, UsernameProps } from './username.types';
 import { UsernameAddedDomainEvent } from './events/username-added.domain-event';
 
 export class UsernameEntity extends AggregateRoot<UsernameProps> {
   protected readonly _id: AggregateID;
 
-  static create = async (create: UsernameProps): Promise<UsernameEntity> => {
+  static create = async (
+    create: CreateUsernameProps,
+  ): Promise<UsernameEntity> => {
     const props: UsernameProps = { ...create };
     const username = new UsernameEntity({
       id: props.name,
diff --git a/src/modules/authentication/core/domain/username.types.ts b/src/modules/authentication/core/domain/username.types.ts
index 382ce83..6f671b0 100644
--- a/src/modules/authentication/core/domain/username.types.ts
+++ b/src/modules/authentication/core/domain/username.types.ts
@@ -1,10 +1,15 @@
-// All properties that a Username has
 export interface UsernameProps {
   name: string;
   userId?: string;
   type: Type;
 }
 
+export interface CreateUsernameProps {
+  name: string;
+  userId: string;
+  type: Type;
+}
+
 export enum Type {
   EMAIL = 'EMAIL',
   PHONE = 'PHONE',
diff --git a/src/modules/authentication/tests/unit/core/authentication.entity.spec.ts b/src/modules/authentication/tests/unit/core/authentication.entity.spec.ts
new file mode 100644
index 0000000..e4e2655
--- /dev/null
+++ b/src/modules/authentication/tests/unit/core/authentication.entity.spec.ts
@@ -0,0 +1,61 @@
+import { AuthenticationEntity } from '@modules/authentication/core/domain/authentication.entity';
+import { CreateAuthenticationProps } from '@modules/authentication/core/domain/authentication.types';
+import { AuthenticationDeletedDomainEvent } from '@modules/authentication/core/domain/events/authentication-deleted.domain-event';
+import { Type } from '@modules/authentication/core/domain/username.types';
+
+const createAuthenticationProps: CreateAuthenticationProps = {
+  userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+  password: 'somePassword',
+  usernames: [
+    {
+      type: Type.EMAIL,
+      name: 'john.doe@email.com',
+    },
+  ],
+};
+
+const createAuthenticationPropsWith2Usernames: CreateAuthenticationProps = {
+  userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+  password: 'somePassword',
+  usernames: [
+    {
+      type: Type.EMAIL,
+      name: 'john.doe@email.com',
+    },
+    {
+      type: Type.PHONE,
+      name: '+33611223344',
+    },
+  ],
+};
+
+describe('Authentication entity create', () => {
+  it('should create a new authentication entity', async () => {
+    const authenticationEntity: AuthenticationEntity =
+      await AuthenticationEntity.create(createAuthenticationProps);
+    expect(authenticationEntity.id).toBe(
+      '165192d4-398a-4469-a16b-98c02cc6f531',
+    );
+    expect(authenticationEntity.domainEvents.length).toBe(1);
+  });
+  it('should create a new authentication entity with 2 usernames', async () => {
+    const authenticationEntity: AuthenticationEntity =
+      await AuthenticationEntity.create(
+        createAuthenticationPropsWith2Usernames,
+      );
+    expect(authenticationEntity.id).toBe(
+      '165192d4-398a-4469-a16b-98c02cc6f531',
+    );
+    expect(authenticationEntity.getProps().usernames.length).toBe(2);
+    expect(authenticationEntity.domainEvents.length).toBe(1);
+  });
+  it('should delete an authentication entity', async () => {
+    const authenticationEntity: AuthenticationEntity =
+      await AuthenticationEntity.create(createAuthenticationProps);
+    authenticationEntity.delete();
+    expect(authenticationEntity.domainEvents.length).toBe(2);
+    expect(authenticationEntity.domainEvents[1]).toBeInstanceOf(
+      AuthenticationDeletedDomainEvent,
+    );
+  });
+});
diff --git a/src/modules/authentication/tests/unit/core/create-authentication.service.spec.ts b/src/modules/authentication/tests/unit/core/create-authentication.service.spec.ts
new file mode 100644
index 0000000..b4b1d25
--- /dev/null
+++ b/src/modules/authentication/tests/unit/core/create-authentication.service.spec.ts
@@ -0,0 +1,131 @@
+import {
+  AggregateID,
+  ConflictException,
+  UniqueConstraintException,
+} from '@mobicoop/ddd-library';
+import { AUTHENTICATION_REPOSITORY } from '@modules/authentication/authentication.di-tokens';
+import { CreateAuthenticationCommand } from '@modules/authentication/core/application/commands/create-authentication/create-authentication.command';
+import { CreateAuthenticationService } from '@modules/authentication/core/application/commands/create-authentication/create-authentication.service';
+import { AuthenticationEntity } from '@modules/authentication/core/domain/authentication.entity';
+import {
+  AuthenticationAlreadyExistsException,
+  UsernameAlreadyExistsException,
+} from '@modules/authentication/core/domain/authentication.errors';
+import { Type } from '@modules/authentication/core/domain/username.types';
+import { CreateAuthenticationRequestDto } from '@modules/authentication/interface/grpc-controllers/dtos/create-authentication.request.dto';
+import { Test, TestingModule } from '@nestjs/testing';
+
+const createAuthenticationRequest: CreateAuthenticationRequestDto = {
+  userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+  password: 'somePassword',
+  usernames: [
+    {
+      name: 'john.doe@email.com',
+      type: Type.EMAIL,
+    },
+  ],
+};
+
+const mockAuthenticationRepository = {
+  insert: jest
+    .fn()
+    .mockImplementationOnce(() => ({}))
+    .mockImplementationOnce(() => {
+      throw new ConflictException('already exists');
+    })
+    .mockImplementationOnce(() => {
+      throw new UniqueConstraintException('uuid');
+    })
+    .mockImplementationOnce(() => {
+      throw new UniqueConstraintException('username');
+    })
+    .mockImplementationOnce(() => {
+      throw new Error();
+    }),
+};
+
+describe('create-authentication.service', () => {
+  let createAuthenticationService: CreateAuthenticationService;
+
+  beforeAll(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        {
+          provide: AUTHENTICATION_REPOSITORY,
+          useValue: mockAuthenticationRepository,
+        },
+        CreateAuthenticationService,
+      ],
+    }).compile();
+
+    createAuthenticationService = module.get<CreateAuthenticationService>(
+      CreateAuthenticationService,
+    );
+  });
+
+  it('should be defined', () => {
+    expect(createAuthenticationService).toBeDefined();
+  });
+
+  describe('execution', () => {
+    const createAdCommand = new CreateAuthenticationCommand(
+      createAuthenticationRequest,
+    );
+    it('should create a new authentication', async () => {
+      AuthenticationEntity.create = jest.fn().mockReturnValue({
+        id: '165192d4-398a-4469-a16b-98c02cc6f531',
+        getProps: jest.fn().mockImplementation(() => ({
+          userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+        })),
+      });
+      const result: AggregateID = await createAuthenticationService.execute(
+        createAdCommand,
+      );
+      expect(result).toBe('165192d4-398a-4469-a16b-98c02cc6f531');
+    });
+    it('should throw a dedicated exception if Authentication already exists', async () => {
+      AuthenticationEntity.create = jest.fn().mockReturnValue({
+        id: '165192d4-398a-4469-a16b-98c02cc6f531',
+        getProps: jest.fn().mockImplementation(() => ({
+          userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+        })),
+      });
+      await expect(
+        createAuthenticationService.execute(createAdCommand),
+      ).rejects.toBeInstanceOf(AuthenticationAlreadyExistsException);
+    });
+    it('should throw a dedicated exception if uuid already exists', async () => {
+      AuthenticationEntity.create = jest.fn().mockReturnValue({
+        id: '165192d4-398a-4469-a16b-98c02cc6f531',
+        getProps: jest.fn().mockImplementation(() => ({
+          userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+        })),
+      });
+      await expect(
+        createAuthenticationService.execute(createAdCommand),
+      ).rejects.toBeInstanceOf(AuthenticationAlreadyExistsException);
+    });
+    it('should throw a dedicated exception if username already exists', async () => {
+      AuthenticationEntity.create = jest.fn().mockReturnValue({
+        id: '165192d4-398a-4469-a16b-98c02cc6f531',
+        getProps: jest.fn().mockImplementation(() => ({
+          userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+        })),
+      });
+      await expect(
+        createAuthenticationService.execute(createAdCommand),
+      ).rejects.toBeInstanceOf(UsernameAlreadyExistsException);
+    });
+    it('should throw an error if something bad happens', async () => {
+      AuthenticationEntity.create = jest.fn().mockReturnValue({
+        id: '165192d4-398a-4469-a16b-98c02cc6f531',
+        getProps: jest.fn().mockImplementation(() => ({
+          userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+        })),
+      });
+      await expect(
+        createAuthenticationService.execute(createAdCommand),
+      ).rejects.toBeInstanceOf(Error);
+    });
+  });
+});
diff --git a/src/modules/authentication/tests/unit/core/username.entity.spec.ts b/src/modules/authentication/tests/unit/core/username.entity.spec.ts
new file mode 100644
index 0000000..2cb19c5
--- /dev/null
+++ b/src/modules/authentication/tests/unit/core/username.entity.spec.ts
@@ -0,0 +1,21 @@
+import { UsernameEntity } from '@modules/authentication/core/domain/username.entity';
+import {
+  CreateUsernameProps,
+  Type,
+} from '@modules/authentication/core/domain/username.types';
+
+const createUsernameProps: CreateUsernameProps = {
+  userId: '165192d4-398a-4469-a16b-98c02cc6f531',
+  type: Type.EMAIL,
+  name: 'john.doe@email.com',
+};
+
+describe('Username entity create', () => {
+  it('should create a new username entity', async () => {
+    const usernameEntity: UsernameEntity = await UsernameEntity.create(
+      createUsernameProps,
+    );
+    expect(usernameEntity.id).toBe('john.doe@email.com');
+    expect(usernameEntity.domainEvents.length).toBe(1);
+  });
+});
diff --git a/src/modules/authentication/tests/unit/infrastructure/authentication.repository.spec.ts b/src/modules/authentication/tests/unit/infrastructure/authentication.repository.spec.ts
new file mode 100644
index 0000000..c7aec80
--- /dev/null
+++ b/src/modules/authentication/tests/unit/infrastructure/authentication.repository.spec.ts
@@ -0,0 +1,37 @@
+import { AuthenticationMapper } from '@modules/authentication/authentication.mapper';
+import { AuthenticationRepository } from '@modules/authentication/infrastructure/authentication.repository';
+import { PrismaService } from '@modules/authentication/infrastructure/prisma.service';
+import { EventEmitter2, EventEmitterModule } from '@nestjs/event-emitter';
+import { Test, TestingModule } from '@nestjs/testing';
+
+const mockMessagePublisher = {
+  publish: jest.fn().mockImplementation(),
+};
+
+describe('Authentication repository', () => {
+  let prismaService: PrismaService;
+  let authenticationMapper: AuthenticationMapper;
+  let eventEmitter: EventEmitter2;
+
+  beforeAll(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      imports: [EventEmitterModule.forRoot()],
+      providers: [PrismaService, AuthenticationMapper],
+    }).compile();
+
+    prismaService = module.get<PrismaService>(PrismaService);
+    authenticationMapper =
+      module.get<AuthenticationMapper>(AuthenticationMapper);
+    eventEmitter = module.get<EventEmitter2>(EventEmitter2);
+  });
+  it('should be defined', () => {
+    expect(
+      new AuthenticationRepository(
+        prismaService,
+        authenticationMapper,
+        eventEmitter,
+        mockMessagePublisher,
+      ),
+    ).toBeDefined();
+  });
+});
diff --git a/src/modules/authentication/tests/unit/infrastructure/username.repository.spec.ts b/src/modules/authentication/tests/unit/infrastructure/username.repository.spec.ts
new file mode 100644
index 0000000..16f9124
--- /dev/null
+++ b/src/modules/authentication/tests/unit/infrastructure/username.repository.spec.ts
@@ -0,0 +1,36 @@
+import { UsernameMapper } from '@modules/authentication/username.mapper';
+import { PrismaService } from '@modules/authentication/infrastructure/prisma.service';
+import { EventEmitter2, EventEmitterModule } from '@nestjs/event-emitter';
+import { Test, TestingModule } from '@nestjs/testing';
+import { UsernameRepository } from '@modules/authentication/infrastructure/username.repository';
+
+const mockMessagePublisher = {
+  publish: jest.fn().mockImplementation(),
+};
+
+describe('Username repository', () => {
+  let prismaService: PrismaService;
+  let usernameMapper: UsernameMapper;
+  let eventEmitter: EventEmitter2;
+
+  beforeAll(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      imports: [EventEmitterModule.forRoot()],
+      providers: [PrismaService, UsernameMapper],
+    }).compile();
+
+    prismaService = module.get<PrismaService>(PrismaService);
+    usernameMapper = module.get<UsernameMapper>(UsernameMapper);
+    eventEmitter = module.get<EventEmitter2>(EventEmitter2);
+  });
+  it('should be defined', () => {
+    expect(
+      new UsernameRepository(
+        prismaService,
+        usernameMapper,
+        eventEmitter,
+        mockMessagePublisher,
+      ),
+    ).toBeDefined();
+  });
+});