在Node + Express appp中用Mocha和Chai进行测试尝试捕捉。

Question

我有一个简单的路由的nodeJS应用程序，如下图所示，我能够使用下面的代码成功地测试try块，但我如何测试catch块？

const express = require('express')
const router = express.Router();
const logger = require('../logger');

router.use('/logMessage',(req, res)  => {
    try {
        logger.info(req.query.message);
        res.send({
            statusMessage: 'success'
        })
    } catch (err) {
        logger.error('error in logging');
        logger.error(err);
        res.send({
            statusMessage: 'failure'
        })
    }
});

module.exports = router;

我可以使用下面的代码成功地测试try块，但我如何测试catch块？

测试 try 块。

describe('GET /logMessage', () => {
    it('should host logger api', (done) => {
        chai.request(server)
            .get('/logMessage?message=testMessage')
            .end((err, response) => {
                response.should.have.status(200);
                done();
            });
    });
});

Answer 1

你需要让try块中的语句抛出一个错误。你可以使用 sinonjs. 为了在这里做示范，我将重写一个关于 console.info，当信息是 "makeError"抛出一个错误。

例如

router.js:

const express = require('express');
const router = express.Router();

const logger = console;

router.use('/logMessage', (req, res) => {
  try {
    logger.info(req.query.message);
    res.send({
      statusMessage: 'success',
    });
  } catch (err) {
    logger.error('error in logging');
    logger.error(err);
    res.send({
      statusMessage: 'failure',
    });
  }
});

module.exports = router;

server.js:

const express = require('express');
const app = express();
const router = require('./router');

const port = 3000;
app.use(router);

if (require.main === module) {
  app.listen(port, () => console.log('server is listening on port:' + port));
}

module.exports = app;

server.test.js:

const server = require('./server');
const chai = require('chai');
const sinon = require('sinon');
const chaiHttp = require('chai-http');
chai.use(chaiHttp);
chai.should();

describe('62080151', () => {
  describe('GET /logMessage', () => {
    it('should host logger api', (done) => {
      chai
        .request(server)
        .get('/logMessage?message=testMessage')
        .end((err, response) => {
          response.should.have.status(200);
          done();
        });
    });

    it('should handle error', (done) => {
      sinon.stub(console, 'info').callsFake((message) => {
        if (message === 'makeError') {
          throw new Error('custom error');
        }
      });
      sinon.spy(console, 'error');
      chai
        .request(server)
        .get('/logMessage?message=makeError')
        .end((err, response) => {
          response.should.have.status(200);
          sinon.assert.match(console.error.firstCall.calledWithExactly('error in logging'), true);
          console.error.secondCall.args[0].should.be.instanceOf(Error);
          done();
        });
    });
  });
});

集成测试结果与覆盖率报告。

  62080151
    GET /logMessage
testMessage
      ✓ should host logger api
error in logging
Error: custom error
    at Console.sinon.stub.callsFake (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/src/stackoverflow/62080151/server.test.js:23:17)
    at Object.invoke (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/sinon/lib/sinon/behavior.js:163:32)
    at Console.functionStub (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/sinon/lib/sinon/stub.js:39:43)
    at Function.invoke (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/sinon/lib/sinon/proxy-invoke.js:47:47)
    at Console.bound consoleCall [as info] (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/sinon/lib/sinon/proxy.js:214:26)
    at router.use (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/src/stackoverflow/62080151/router.js:1:1894)
    at Layer.handle [as handle_request] (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:317:13)
    at /Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:275:10)
    at Function.handle (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:174:3)
    at router (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:47:12)
    at Layer.handle [as handle_request] (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:317:13)
    at /Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:275:10)
    at expressInit (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/middleware/init.js:40:5)
    at Layer.handle [as handle_request] (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:317:13)
    at /Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:275:10)
    at query (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/middleware/query.js:45:5)
    at Layer.handle [as handle_request] (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:317:13)
    at /Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:275:10)
    at Function.handle (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/router/index.js:174:3)
    at Function.handle (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/application.js:174:10)
    at Server.app (/Users/ldu020/workspace/github.com/mrdulin/expressjs-research/node_modules/express/lib/express.js:39:9)
    at Server.emit (events.js:198:13)
    at parserOnIncoming (_http_server.js:677:12)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:109:17)
      ✓ should handle error (43ms)


  2 passing (81ms)

-----------|---------|----------|---------|---------|-------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
-----------|---------|----------|---------|---------|-------------------
All files  |      90 |       50 |      50 |   94.74 |                   
 router.js |     100 |      100 |     100 |     100 |                   
 server.js |   77.78 |       50 |       0 |    87.5 | 9                 
-----------|---------|----------|---------|---------|-------------------