log4js-node/test/tap/file-descriptor-leak-test.js

const { test } = require("tap");
const fs = require("fs");
const path = require("path");
const log4js = require("../../lib/log4js");

const removeFiles = async filenames => {
  if (!Array.isArray(filenames))
    filenames = [filenames];
  const promises = filenames.map(filename => fs.promises.unlink(filename));
  await Promise.allSettled(promises);
};

// no file descriptors on Windows, so don't run the tests
if (process.platform !== "win32") {

  test("multiple log4js configure fd leak test", batch => {
    const config = {
      appenders: {},
      categories: {
        default: { appenders: [], level: 'debug' }
      }
    };

    // create 11 appenders
    const numOfAppenders = 11;
    for (let i = 1; i <= numOfAppenders; i++) {
      config.appenders[`app${i}`] = { type: 'file', filename: path.join(__dirname, `file${i}.log`) };
      config.categories.default.appenders.push(`app${i}`);
    }

    const initialFd = fs.readdirSync('/proc/self/fd').length;
    let loadedFd;

    batch.test("initial log4js configure to increase file descriptor count", t => {
      log4js.configure(config);

      // wait for the file system to catch up
      setTimeout(() => {
        loadedFd = fs.readdirSync('/proc/self/fd').length;
        t.equal(loadedFd, initialFd + numOfAppenders, 
          `file descriptor count should increase by ${numOfAppenders} after 1st configure() call`);
        t.end();
      }, 250);
    });

    batch.test("repeated log4js configure to not increase file descriptor count", t => {
      log4js.configure(config);
      log4js.configure(config);
      log4js.configure(config);

      // wait for the file system to catch up
      setTimeout(() => {
        t.equal(fs.readdirSync('/proc/self/fd').length, loadedFd, 
          `file descriptor count should be identical after repeated configure() calls`);
        t.end();
      }, 250);
    });

    batch.test("file descriptor count should return back to initial count", t => {
      log4js.shutdown();

      // wait for the file system to catch up
      setTimeout(() => {
        t.equal(fs.readdirSync('/proc/self/fd').length, initialFd, 
          `file descriptor count should be back to initial`);
        t.end();
      }, 250);
    });

    batch.teardown(async () => {
      await new Promise(resolve => { log4js.shutdown(resolve); });

      const filenames = Object.values(config.appenders).map(appender => appender.filename);
      await removeFiles(filenames);
    });

    batch.end();
  });

}