mailer.service.spec.ts

import { HttpModule } from '@nestjs/common';
import { Test, TestingModule } from '@nestjs/testing';
import { ConfigurationService } from '../configuration/configuration.service';
import { MailerService } from './mailer.service';

describe('MailerService', () => {
  let service: MailerService;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      imports: [HttpModule],
      providers: [MailerService, ConfigurationService],
    }).compile();

    service = module.get<MailerService>(MailerService);
  });

  it('should be defined', () => {
    expect(service).toBeDefined();
  });
  
  it('should send email', async () => {
    const result = "AxiosResponse"
    jest.spyOn(service, 'send').mockImplementation(async (): Promise<any> => result);
    expect(await service.send("to", "subject", "html")).toBe(result);
  });

  it('should get template location', async () => {
    const result = "/path/to/template";
    jest.spyOn(service, 'getTemplateLocation').mockImplementation(() => {return result});
    expect(await service.getTemplateLocation("filename")).toBe(result);
  });

  it('should load Json Config', async () => {
    const result = null;
    jest.spyOn(service, 'loadJsonConfig').mockImplementation(async (): Promise<any> => result);
    expect(await service.loadJsonConfig("filename")).toBe(result);
  });

  it('should add signature', async () => {
    const result = "signed html";
    jest.spyOn(service, 'addSignature').mockImplementation(() => {return result});
    expect(await service.addSignature("html")).toBe(result);
  });
});