SerpentRace/SerpentRace_Backend/tests/Application/Services/EmailService.test.ts

import { EmailService, EmailOptions } from '../../../src/Application/Services/EmailService';
import * as nodemailer from 'nodemailer';
import * as fs from 'fs';

// Mock nodemailer
jest.mock('nodemailer');
jest.mock('fs');

// Mock logger
jest.mock('../../../src/Application/Services/Logger', () => ({
  logError: jest.fn(),
  logAuth: jest.fn(),
  logStartup: jest.fn(),
}));

describe('EmailService', () => {
  let emailService: EmailService;
  let mockTransporter: jest.Mocked<nodemailer.Transporter>;
  let mockCreateTransporter: jest.MockedFunction<typeof nodemailer.createTransport>;

  beforeEach(() => {
    jest.clearAllMocks();

    // Mock nodemailer.createTransporter
    mockTransporter = {
      sendMail: jest.fn(),
    } as any;
    
    mockCreateTransporter = nodemailer.createTransport as jest.MockedFunction<typeof nodemailer.createTransport>;
    mockCreateTransporter.mockReturnValue(mockTransporter);

    // Mock fs
    (fs.readFileSync as jest.Mock).mockImplementation((filePath: string) => {
      if (filePath.includes('html')) {
        return 'HTML template: {{name}}';
      }
      return 'Text template: {{name}}';
    });

    (fs.existsSync as jest.Mock).mockReturnValue(true);

    emailService = new EmailService();
  });

  describe('sendEmail', () => {
    it('should send email successfully', async () => {
      // Arrange
      const emailOptions: EmailOptions = {
        to: 'test@example.com',
        subject: 'Test Subject',
        html: '<p>Test HTML</p>',
        text: 'Test Text',
      };

      mockTransporter.sendMail.mockResolvedValue({ messageId: 'test-id' });

      // Act
      const result = await emailService.sendEmail(emailOptions);

      // Assert
      expect(result).toBe(true);
      expect(mockTransporter.sendMail).toHaveBeenCalledWith({
        from: process.env.EMAIL_FROM || 'noreply@serpentrace.com',
        to: emailOptions.to,
        subject: emailOptions.subject,
        html: emailOptions.html,
        text: emailOptions.text,
      });
    });

    it('should send email with template', async () => {
      // Arrange
      const emailOptions: EmailOptions = {
        to: 'test@example.com',
        subject: 'Test Subject',
        template: 'verification',
        templateData: { name: 'John', token: 'abc123' },
      };

      mockTransporter.sendMail.mockResolvedValue({ messageId: 'test-id' });

      // Act
      const result = await emailService.sendEmail(emailOptions);

      // Assert
      expect(result).toBe(true);
      expect(mockTransporter.sendMail).toHaveBeenCalledWith({
        from: process.env.EMAIL_FROM || 'noreply@serpentrace.com',
        to: emailOptions.to,
        subject: emailOptions.subject,
        html: expect.stringContaining('John'),
        text: expect.stringContaining('John'),
      });
    });

    it('should handle email send failure', async () => {
      // Arrange
      const emailOptions: EmailOptions = {
        to: 'test@example.com',
        subject: 'Test Subject',
        text: 'Test Text',
      };

      mockTransporter.sendMail.mockRejectedValue(new Error('SMTP Error'));

      // Act
      const result = await emailService.sendEmail(emailOptions);

      // Assert
      expect(result).toBe(false);
    });

    it('should handle missing template files', async () => {
      // Arrange
      const emailOptions: EmailOptions = {
        to: 'test@example.com',
        subject: 'Test Subject',
        template: 'nonexistent',
        templateData: { name: 'John' },
      };

      (fs.existsSync as jest.Mock).mockReturnValue(false);

      // Act
      const result = await emailService.sendEmail(emailOptions);

      // Assert
      expect(result).toBe(false);
    });

    it('should handle template processing errors', async () => {
      // Arrange
      const emailOptions: EmailOptions = {
        to: 'test@example.com',
        subject: 'Test Subject',
        template: 'verification',
        templateData: { name: 'John' },
      };

      (fs.readFileSync as jest.Mock).mockImplementation(() => {
        throw new Error('File read error');
      });

      // Act
      const result = await emailService.sendEmail(emailOptions);

      // Assert
      expect(result).toBe(false);
    });

    it('should use fallback content when template data is missing', async () => {
      // Arrange
      const emailOptions: EmailOptions = {
        to: 'test@example.com',
        subject: 'Test Subject',
        template: 'verification',
      };

      mockTransporter.sendMail.mockResolvedValue({ messageId: 'test-id' });

      // Act
      const result = await emailService.sendEmail(emailOptions);

      // Assert
      expect(result).toBe(true);
    });
  });

  describe('constructor', () => {
    it('should initialize with environment variables', () => {
      // Arrange
      const originalEnv = process.env;
      process.env = {
        ...originalEnv,
        EMAIL_HOST: 'test-smtp.com',
        EMAIL_PORT: '465',
        EMAIL_SECURE: 'true',
        EMAIL_USER: 'test@example.com',
        EMAIL_PASS: 'testpass',
        EMAIL_FROM: 'sender@example.com',
      };

      // Act
      const service = new EmailService();

      // Assert
      expect(mockCreateTransporter).toHaveBeenCalledWith({
        host: 'test-smtp.com',
        port: 465,
        secure: true,
        auth: {
          user: 'test@example.com',
          pass: 'testpass',
        },
      });

      // Restore environment
      process.env = originalEnv;
    });

    it('should use default values when environment variables are missing', () => {
      // Arrange
      const originalEnv = process.env;
      process.env = {};

      // Act
      const service = new EmailService();

      // Assert
      expect(mockCreateTransporter).toHaveBeenCalledWith({
        host: 'smtp.gmail.com',
        port: 587,
        secure: false,
        auth: {
          user: '',
          pass: '',
        },
      });

      // Restore environment
      process.env = originalEnv;
    });
  });
});