MongoDB连接期间的Mocha超时

Mocha测试用例与普通JS代码没有什么不同，因此它将遵循JS代码的范围隔离和流程。我试图修复测试用例，以允许在各种测试用例中以及钩子之前/之后进行变量访问。

请注意，我尚未执行实际的测试用例，您可能需要修改以下代码以使其成功运行

'use strict';
 const mongoose = require('mongoose');
 const Schema = mongoose.Schema;
 const chai = require('chai');
 const expect = chai.expect;



 /**
  * 
  * Create a new schema that accepts a firstname and lastname and employee id
  */
 const testSchema = new Schema({
     firstname: { type: String, required: true },
     lastname: { type: String, required: true },
     id: { type: Number, required: true }
 });

 /**
  * 
  * Create a new collection name employee_details 
  */
 const employee_details = mongoose.model('employee_details', testSchema);

 /**
  * Decalre the db const in this(global) context so this variable is visible by all test cases
  */
 const db;

 //  describe('Create a connection with the database', () => {
 //      // Seems redundet to something
 //      // Also the context is lost if you do this .. 
 //      // Thus not allowing for you to use variables .. const db in this case
 //      // If you still want this describe, you will have to use it like any other javascript function ... to expose the variables
 //  });


 describe('Test Database function', () => {

     // connect to database     
     before((done) => {
         mongoose.connect('mongodb://127.0.0.1:27017/new_demo');
         //Keep the url same which you use to debug you local application
         db = mongoose.connection;
         db.on('error', console.error.bind(console, 'Error connecting to DB'));
         db.once('open', () => {
             console.log('Connected to new_demo db');
             done();
         });
     });

     //Save something with value Mike Stevens, 19981
     it('saves a new record', (done) => {
         // Also if you want to increase the deafult timeout of a teast case
         // you will have to change the => to function(), because of the way 'this' context behaves
         // Thus : 
         //   it('saves a new record', function(done) {
         //      this.timeout(10000);
         //      .. test case code
         //   }
         var first_record = employee_details({
             firstname: 'Mike',
             lastname: 'Stevens',
             id: 19981
         });

         first_record.save(function(err) {
             if (err) return handleError(err);
             // saved!
             done();
             //I used a simple callback function instead, makes life easier and code understable
         })
     });



     after((done) => {
         mongoose.connection.db.dropDatabase(() => {
             mongoose.connection.close(done);
             // I am guessing same goes here .. 
             // keep it simple !!
         });
     });
 });

现在有一些理论，理想情况下，不建议或者不建议在单元测试用例的范围内以任何方式实际连接到数据库和/或修改外部实体的状态（因为您明确提到“它是一个单元”测试用例'）。

单元测试应避免进行外部调用或调用实际的API。我们应该对调用进行存根，并在测试用例中断言该调用是在我们期望的时间或提供适当的输入时进行的。

这是一个例子：

//This is myGLobalServiceLoactor which is used in actual code which is to be tested.
 myGLobalServiceLoactor = {
     database: {
         save: sinon.stub(),
         find: sinon.stub()
     }
 }

 it('to check if external method is called ', () => {
     let person_to_Save = {
         //. . . 
         //. . . 
     }
     proxyPersonInterface.savePerson(input_person).then((status) => {
         // check if our stubbeb function is called
         assert(myGLobalServiceLoactor.database.save.calledOnce);
     });

 });

而且，您可以使用诸如Sinon之类的帮助程序库和rewire来对单元测试用例中的实际模块进行存根和代理。希望能有所帮助。