如何解决参考错误：记录器未定义

Question

在运行某些测试时，我当前收到“ ReferenceError：未定义记录器”错误。当我的端点位于我的app.js中时，没有发生这些错误。它们仅在我将端点移到路由器文件中时才开始发生。

我的所有端点都可以在邮递员中工作，并且可以检索数据，但是由于某些原因，我的所有测试均失败。路由器文件中是否缺少某些内容？

const express = require("express");
const uuid = require("uuid/v4");
const logger = require("../logger");
const { bookmarks } = require("../store");
const BookmarksService = require("../bookmarks-service");

const bookmarkRouter = express.Router();
const bodyParser = express.json();

bookmarkRouter
  .route("/bookmarks")
  .get((req, res, next) => {
    const knexInstance = req.app.get("db");
    BookmarksService.getAllBookmarks(knexInstance)
      .then(bookmarks => {
        res.json(bookmarks);
      })
      .catch(next);
  })
  .post(bodyParser, (req, res) => {
    //implementation
    for (const field of ["title", "url", "rating"]) {
      if (!req.body[field]) {
        logger.error(`${field} is required`);
        return res.status(400).send(`${field} is required`);
      }
    }

    const { title, url, rating, desc } = req.body;

    if (!title) {
      logger.error("Title is required");
      return res.status(400).send("Invalid data");
    }

    if (!url) {
      logger.error("Url is required");
      return res.status(400).send("Invalid data");
    }

    if (!desc) {
      logger.error("Desc is required");
      return res.status(400).send("Invalid data");
    }

    const id = uuid();

    const bookmark = {
      id,
      title,
      url,
      rating,
      desc
    };

    bookmarks.push(bookmark);

    logger.info(`Bookmark with bookmark ${id} created`);

    res
      .status(201)
      .location(`http://localhost.8000/bookmark/${id}`)
      .json(bookmark);
  });

bookmarkRouter
  .route("/bookmarks/:id")
  .get((req, res, next) => {
    //implementation
    const { id } = req.params;
    const bookmark = bookmarks.find(b => b.id == id);
    const knexInstance = req.app.get("db");
    BookmarksService.getById(knexInstance, id)
      .then(bookmark => {
        if (!bookmark) {
          logger.error(`Bookmark with id ${id} not found`);
          return res.status(404).send({
            error: { message: `Bookmark doesn't exist` }
          });
        }
        res.json(bookmark);
      })
      .catch(next);
  })
  .delete((req, res) => {
    //implementation
    const { id } = req.params;

    const bookmarkIndex = bookmarks.findIndex(li => li.id == id);

    if (bookmarkIndex === -1) {
      logger.error(`Bookmark with id ${id} not found.`);
      return res.status(400).send("Not found");
    }

    bookmarks.splice(bookmarkIndex, 1);

    logger.info(`Bookmark with id ${id} deleted`);
    res.status(204).end();
  });

module.exports = bookmarkRouter;