log4js-node/test/tap/pause-test.js

const tap = require('tap');
const fs = require('fs');
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);
};

tap.test('Drain event test', (batch) => {
  batch.test(
    'Should emit pause event and resume when logging in a file with high frequency',
    (t) => {
      t.teardown(async () => {
        process.off(
          'log4js:pause',
          process.listeners('log4js:pause')[
            process.listeners('log4js:pause').length - 1
          ]
        );
        await removeFiles('logs/drain.log');
      });
      // Generate logger with 5k of highWaterMark config
      log4js.configure({
        appenders: {
          file: {
            type: 'file',
            filename: 'logs/drain.log',
            highWaterMark: 5 * 1024,
          },
        },
        categories: {
          default: { appenders: ['file'], level: 'debug' },
        },
      });

      let paused = false;
      let resumed = false;

      process.on('log4js:pause', (value) => {
        if (value) {
          paused = true;
          t.ok(value, 'log4js:pause, true');
        } else {
          resumed = true;
          t.ok(!value, 'log4js:pause, false');
          t.end();
        }
      });

      const logger = log4js.getLogger();
      while (!paused && !resumed) {
        if (!paused) {
          logger.info('This is a test for emitting drain event');
        }
      }
    }
  );

  batch.test(
    'Should emit pause event and resume when logging in a date file with high frequency',
    (t) => {
      t.teardown(async () => {
        process.off(
          'log4js:pause',
          process.listeners('log4js:pause')[
            process.listeners('log4js:pause').length - 1
          ]
        );
        await removeFiles('logs/date-file-drain.log');
      });
      // Generate date file logger with 5kb of highWaterMark config
      log4js.configure({
        appenders: {
          file: {
            type: 'dateFile',
            filename: 'logs/date-file-drain.log',
            highWaterMark: 5 * 1024,
          },
        },
        categories: {
          default: { appenders: ['file'], level: 'debug' },
        },
      });

      let paused = false;
      let resumed = false;

      process.on('log4js:pause', (value) => {
        if (value) {
          paused = true;
          t.ok(value, 'log4js:pause, true');
        } else {
          resumed = true;
          t.ok(!value, 'log4js:pause, false');
          t.end();
        }
      });

      const logger = log4js.getLogger();
      while (!paused && !resumed) {
        if (!paused)
          logger.info(
            'This is a test for emitting drain event in date file logger'
          );
      }
    }
  );

  batch.teardown(async () => {
    try {
      const files = fs.readdirSync('logs');
      await removeFiles(files.map((filename) => `logs/${filename}`));
      fs.rmdirSync('logs');
    } catch (e) {
      // doesn't matter
    }
  });

  batch.end();
});