Test Generation

Input: User Authentication Function

async function authenticateUser(email: string, password: string) {
  if (!email || !password) {
    throw new Error('Email and password are required');
  }
  
  const user = await db.users.findOne({ email });
  if (!user) {
    throw new Error('User not found');
  }
  
  const isValid = await bcrypt.compare(password, user.password);
  if (!isValid) {
    throw new Error('Invalid password');
  }
  
  return generateToken(user);
}

Generated Test Suite

describe('authenticateUser', () => {
  beforeEach(() => {
    jest.clearAllMocks();
  });

  it('should authenticate valid user credentials', async () => {
    const mockUser = {
      email: 'test@example.com',
      password: 'hashedPassword'
    };
    
    db.users.findOne.mockResolvedValue(mockUser);
    bcrypt.compare.mockResolvedValue(true);
    generateToken.mockReturnValue('valid-token');

    const result = await authenticateUser('test@example.com', 'password');
    expect(result).toBe('valid-token');
  });

  it('should throw error for missing credentials', async () => {
    await expect(authenticateUser('', 'password'))
      .rejects.toThrow('Email and password are required');
  });

  it('should throw error for non-existent user', async () => {
    db.users.findOne.mockResolvedValue(null);
    
    await expect(authenticateUser('wrong@example.com', 'password'))
      .rejects.toThrow('User not found');
  });

  it('should throw error for invalid password', async () => {
    const mockUser = {
      email: 'test@example.com',
      password: 'hashedPassword'
    };
    
    db.users.findOne.mockResolvedValue(mockUser);
    bcrypt.compare.mockResolvedValue(false);

    await expect(authenticateUser('test@example.com', 'wrongpass'))
      .rejects.toThrow('Invalid password');
  });
});

• Keep Functions Focused: Single responsibility principle helps generate better tests
• Clear Dependencies: Well-defined imports and dependencies improve mock generation
• Type Definitions: Strong typing leads to more accurate test cases
• Documentation: JSDoc comments help AI understand expected behavior