text: import { expect, sinon } from '../common.test';
  import { MailService } from '../../app/services';
  describe("MailService",()=>{
      const sandbox = sinon.createSandbox();
      describe("message",()=>{
          before(()=>{
              // sandbox.stub()
          });
          after(()=>{
              sandbox.restore();
          })
          it("static", (done)=>{
              expect(MailService.message()).to.eventually.equal("Hello World!");
              done();
          });
      });
  });