Mockgoose:如何在mongoose中模拟错误？

Question

我正在尝试做一个mongoose驱动的应用程序的单元测试。虽然mockgoose在模拟mongoose方面做了很好的工作，以便我可以围绕它进行测试，但我没有找到一种方法来推动它使调用失败，所以我可以测试错误处理逻辑。

这是一个受支持的用例吗？或者我应该找到另一个框架？

代码：

var mongoose = require('mongoose');

var Test = {},
    Doc = require('./model/Doc.js');

var dbURL = 'mongodb://127.0.0.1/',
    dbName = 'Test';

function connect(callback) {
    Test = mongoose.createConnection(dbURL + dbName); //<-- Push this to fail
    Test.on('error', (err) => {
        callback(err);
    });
    Test.once('open', function () {
        callback();
    }); 
}

测试：

var chai = require('chai'),
    expect = chai.expect,
    util = require('util');

var config = require('./config.json');

var proxyquire =  require('proxyquire').noPreserveCache();
var sinon = require('sinon');
var mongoose = require('mongoose');
var mockgoose = require('mockgoose');

describe('test', () => {
    describe('Connect', () => {
        beforeEach((callback) => {
            mockgoose(mongoose).then(() => {
                callback();
            });
        });

        it('Expect to connect to the database', (done) => {
            var stub = {
                    mongoose: mongoose
                },
                test = proxyquire('./../test.js', {
                    'mongoose': stub.mongoose
                });

            test.connect((err) => {
                try {
                    expect(err).to.not.be.ok;
                    done();
                } catch(err) {
                    done(err);
                }
            });

        it('Expect to throw error when failing to connect to the database', (done) => {
            var stub = {
                    mongoose: mongoose
                },
                medical = proxyquire('./../medical.js', {
                    'mongoose': stub.mongoose
                });

            medical.connect((err) => {
                try {
                    expect(err).to.be.ok;
                    done();
                } catch(err) {
                    done(err);
                }
            });
        });
    });
});

结果是：

Connect
      ✓ Expect to connect to the database
      1) Expect to throw error when failing to connect to the database


  1 passing (234ms)
  1 failing

  1) Medical Connect Expect to throw error when failing to connect to the database:
     AssertionError: expected undefined to be truthy