Mocha 异步测试因未定义的 AssertError 而失败

Question

我是第一次玩摩卡，我很难让一个简单的测试工作。在分配变量之前调用 returns，因此返回为未定义。

这是我要测试的代码：

var mongodb = require('mongodb')
var querystring = require("querystring");

var mongoURI = process.env.MONGOLAB_URI;
var dbName = process.env.dbName;

//checks for a single email address
var emailAddressExists = function () {
  var returnVal;
  mongodb.connect(mongoURI, function (err, db) {    
    if (err)
      { console.error(err); response.send("Error " + err); }

    var collection = db.collection(dbName); //, function(err, collection) {
    collection.find( { "emailAddress" : "myemail@email.com"} ).count( function (err, count)  {
      if (count == 0) {
        returnVal = false;  
        console.log("not Matched " + returnVal);           
      } else {
        returnVal = true;
        console.log("matched " + returnVal);
      }
      return returnVal;
    });
  });
)
exports.emailAddressExists = emailAddressExists;

我的测试是：

var assert = require('assert'),
    helpers = require ('../lib/helpers.js');

describe('#emailAddressExistsTest()', function() {
  var returnVal;

  it('should return 1 when the value is not present', function(done) {
    assert.equal(true, helpers.emailAddressExists(););
    done();
  });
})

当我运行 'mocha' 我收到以下信息：

#emailAddressExistsTest()
    1) should return 1 when the value is not present


  0 passing (10ms)
  1 failing

  1) #emailAddressExistsTest() should return 1 when the value is not present:
     AssertionError: true == "undefined"
      at Context.<anonymous> (test/emailAddressCheck.js:25:11)

Answer 1

首先，您将要更改 emailAddressExists 以进行回调 - 这是在完成时告诉测试的唯一方法：

var emailAddressExists = function (next) {
  mongodb.connect(mongoURI, function (err, db) {
    if (err) {
      next(err);
    }

    var collection = db.collection(dbName);
    collection.find( { "emailAddress" : "myemail@email.com"} ).count( function (err, count) {
      if (count == 0) {
        next(null, false); 
      } else { 
        next(null, true); 
      } 
      return returnVal;
    });
  });
)

然后，你必须给它传递一个回调并在回调中调用done：

describe('#emailAddressExistsTest()', function() {
  it('should return 1 when the value is not present', function(done) {
    helpers.emailAddressExists(function(err, returnVal) {
      // Maybe do something about `err`?
      assert.equal(true, returnVal);
      done();
    });
  });
})

您会注意到这与我们在聊天中讨论的内容有些不同。 node.js 中的约定是回调的第一个参数是错误（null 如果没有错误），第二个参数是 "return value".

Mocha 异步测试因未定义的 AssertError 而失败

Mocha async test failing with undefined AssertError

mocha.js

mongodb

node.js