在 Mocha 的测试运行之前块中定义的函数未完成

Question

我正在我的 Node 项目中使用 Mocha/Chai 创建一些测试。在一个特定的测试中，我需要先将 document 保存到数据库中，然后再检索它并运行对找到的文档进行一些检查。

我运行遇到的问题是 it 检查在文档完成保存到数据库之前运行进行。我不明白为什么会这样，因为我正在 before() 块中进行保存——根据 Mocha 文档，在同一描述块中的测试之前应该运行，见下文来自文档：

> With its default "BDD"-style interface, Mocha provides the hooks
> before(), after(), beforeEach(), and afterEach(). These should be used
> to set up preconditions and clean up after your tests.
> 
> describe('hooks', function() {   before(function() {
>     // runs before all tests in this block   });
> 
>   after(function() {
>     // runs after all tests in this block   });
> 
>   beforeEach(function() {
>     // runs before each test in this block   });
> 
>   afterEach(function() {
>     // runs after each test in this block   });
> 
>   // test cases });

澄清一下，当我运行第二次（以及所有后续时间）测试时，所有检查都通过了，因为到那时它可以在数据库中找到文档。

我在这里错过了什么？

这是我的代码：

const assert = require("chai").assert;
const expect = require("chai").expect;
const chai = require("chai");
chai.use(require("chai-datetime"));
const Agenda = require('agenda');

const config = require('./../../configuration');
const url = config.get('MONGO_URL');
const dbName = config.get('MONGO_DATABASE');
const collection = config.get('MONGO_COLLECTION');
const createAgendaJob = require('./../../lib/agenda-jobs/contact-firstname-to-proper-case');

const MongoClient = require('mongodb').MongoClient;
const client = new MongoClient(url);

describe("Contact FirstName to Proper Case", async function () {
  const jobName = "Contact FirstName To Proper Case";
  const testDate = new Date(2019, 01, 01);
  let result;
  let agenda;
  this.timeout(2000);
  before(async function () {
    const connectionOpts = {
      db: {
        address: `${url}/${dbName}`,
        collection
      }
    };

    agenda = new Agenda(connectionOpts);
    await new Promise(resolve => agenda.once('ready', resolve));
    await createAgendaJob(agenda); // Here is where I save the job to the DB
  });
  client.connect(async function (err) {
    assert.equal(null, err);

    const db = await client.db(dbName);

    result = await db.collection("jobs").findOne({
      "name": jobName
    });

    client.close();
  });
  it("should have a property 'name'", function () {
    expect(result).to.have.property("name");
  });
  it("should have a 'name' of 'Contact FirstName To Proper Case'", function () {
    expect(result.name).to.equal("Contact FirstName To Proper Case");
  });
  it("should have a property 'type'", function () {
    expect(result).to.have.property("type");
  });
  it("should have a 'type' of 'normal'", function () {
    expect(result.type).to.equal("normal");
  });
  it("should have a property 'repeatTimezone'", function () {
    expect(result).to.have.property("repeatTimezone");
  });
  it("should have a property 'repeatInterval'", function () {
    expect(result).to.have.property("repeatInterval");
  });
  it("should have a property 'lastModifiedBy'", function () {
    expect(result).to.have.property("lastModifiedBy");
  });
  it("should have a property 'nextRunAt'", function () {
    expect(result).to.have.property("nextRunAt");
  });
  it("should return a date for the 'nextRunAt' property", function () {
    assert.typeOf(result.nextRunAt, "date");
  });
  it("should 'nextRunAt' to be a date after test date", function () {
    expect(result.nextRunAt).to.afterDate(testDate);
  });
});

我还尝试将 it 检查放在后续的 describe() 块中，但这也没有用（同样的结果——文档仅在 SECOND 运行上找到测试文件):

const assert = require("chai").assert;
const expect = require("chai").expect;
const chai = require("chai");
chai.use(require("chai-datetime"));
const Agenda = require('agenda');

const config = require('./../../configuration');
const url = config.get('MONGO_URL');
const dbName = config.get('MONGO_DATABASE');
const collection = config.get('MONGO_COLLECTION');
const createAgendaJob = require('./../../lib/agenda-jobs/contact-firstname-to-proper-case');

const MongoClient = require('mongodb').MongoClient;
const client = new MongoClient(url);

describe("Contact FirstName to Proper Case", async function () {
  const jobName = "Contact FirstName To Proper Case";
  const testDate = new Date(2019, 01, 01);
  let result;
  let agenda;
  this.timeout(2000);
  before(async function () {
    const connectionOpts = {
      db: {
        address: `${url}/${dbName}`,
        collection
      }
    };

    agenda = new Agenda(connectionOpts);
    await new Promise(resolve => agenda.once('ready', resolve));
    await createAgendaJob(agenda); // Here is where I save the job to the DB
  });
  client.connect(async function (err) {
    assert.equal(null, err);

    const db = await client.db(dbName);

    result = await db.collection("jobs").findOne({
      "name": jobName
    });

    client.close();
  });
  describe("Check Contact FirstName To ProperCase Found Job", function () {
    it("should have a property 'name'", function () {
      expect(result).to.have.property("name");
    });
    it("should have a 'name' of 'Contact FirstName To Proper Case'", function () {
      expect(result.name).to.equal("Contact FirstName To Proper Case");
    });
    it("should have a property 'type'", function () {
      expect(result).to.have.property("type");
    });
    it("should have a 'type' of 'normal'", function () {
      expect(result.type).to.equal("normal");
    });
    it("should have a property 'repeatTimezone'", function () {
      expect(result).to.have.property("repeatTimezone");
    });
    it("should have a property 'repeatInterval'", function () {
      expect(result).to.have.property("repeatInterval");
    });
    it("should have a property 'lastModifiedBy'", function () {
      expect(result).to.have.property("lastModifiedBy");
    });
    it("should have a property 'nextRunAt'", function () {
      expect(result).to.have.property("nextRunAt");
    });
    it("should return a date for the 'nextRunAt' property", function () {
      assert.typeOf(result.nextRunAt, "date");
    });
    it("should 'nextRunAt' to be a date after test date", function () {
      expect(result.nextRunAt).to.afterDate(testDate);
    });
  });
});

Answer 1

it 运行ning 之前 before 完成，但这是运行一切之前:

    client.connect(async function (err) {
     ...
    });

Mocha，当创建测试 suide 时运行s 代码如下：

调用传递给 describe
的每个函数
- 收集所有 it 和 before/after* 钩子
- 那是您的 client.connect 片段实际被调用的时间！
然后，在创建整个 suite/test 树之后，对于每个套件
- 在* hooks 之前调用适当的方法
- 调用所有 its - 测试，可能被 before/afterAll 钩子包围
- 调用 after 钩子

每个挂钩/测试运行至少在您的情况下等待完成，因为您正确使用 async/await

此外，请注意，这很可疑：

await setTimeout(() => {
  console.log('finished pausing for 5 seconds...');
}, 5000);

这不会等待任何事情，因为 setTimeout returns 对其进行计时（可能是数字）并且没有很好地定义 await 应该如何处理这些数据，因为这不是承诺。当然，它不会等待 5 秒。

正确的承诺等待如下所示：

await new Promise(resolve => setTimeout(resolve, 5000))

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