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node.js - 笑话：process.env.PORT 的测试问题

问题描述

编辑：玩了一会儿后，我意识到问题与流程变量无关，而是与我的服务器实例出于某种原因仅执行一次这一事实有关。我还在研究中，我会保持帖子更新。

我试图获得 100% 的覆盖率，但我一直在测试这条线：

const port = config.get("port") || process.env.PORT || 3000;

看来我不能设置process.env.PORT不止一次。

const config = require("config");

// This checks if a port is being used
function portUsed(port) {
  return new Promise((resolve, reject) => {
    const net = require("net");
    const server = net.createServer();

    server.once("error", err => {
      if (err.code === "EADDRINUSE") {
        resolve(true);
      }
    });

    server.once("listening", () => {
      server.close();
      resolve(false);
    });

    server.listen(port);
  });
}

describe("index", () => {
  // this works
  it("should use process.env.PORT if config.get('port') is not set", async () => {
    config.port = null;
    process.env.PORT = 3333;
    const server = require("../../index");
    const result = await portUsed(3333);
    expect(result).toBe(true);
    await server.close();
  });

  // This does not work, but if you comment out / remove the previous test, it will work!
  it("should default to port 3000 if other variables are not set", async () => {
    config.port = null;
    delete process.env.PORT;
    const server = require("../../index");
    const result = await portUsed(3000);
    expect(result).toBe(true);
    await server.close();
  });

});

基本上这两个测试中只有一个会运行。我究竟做错了什么？

index.js

const express = require("express");
const app = express();
const config = require("config");

const logger = require("./startup/logging");
require("./startup/console")(app);
require("./startup/database")();
require("./startup/routes")(app);

app.use(express.urlencoded({ extended: true }));

logger.info(config.get("name"));
// delete config.port;
// delete process.env.PORT;
// console.log("config", config.port);
console.log("server", process.env.PORT);
const port = config.get("port") || process.env.PORT || 3000;
const server = app.listen(port, () => logger.info(`Listening on port ${port}.`));

module.exports = server;

标签： node.jsexpressjestjsenvironment-variablesport

解决方案

我的测试不工作的原因是需要的模块（require("../../index.js")）将被缓存，因此只创建了一个服务器实例。要解决这个问题，只需使用：

beforeEach(() => jest.resetModules());

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