nodejs/test/parallel/test-process-beforeexit.js

// Copyright Joyent, Inc. and other Node contributors.
//
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// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
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// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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// USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';
const common = require('../common');
const net = require('net');

process.once('beforeExit', common.mustCall(tryImmediate));

function tryImmediate() {
  setImmediate(common.mustCall(() => {
    process.once('beforeExit', common.mustCall(tryTimer));
  }));
}

function tryTimer() {
  setTimeout(common.mustCall(() => {
    process.once('beforeExit', common.mustCall(tryListen));
  }), 1);
}

function tryListen() {
  net.createServer()
    .listen(0)
    .on('listening', common.mustCall(function() {
      this.close();
      process.once('beforeExit', common.mustCall(tryRepeatedTimer));
    }));
}

// Test that a function invoked from the beforeExit handler can use a timer
// to keep the event loop open, which can use another timer to keep the event
// loop open, etc.
//
// After N times, call function `tryNextTick` to test behaviors of the
// `process.nextTick`.
function tryRepeatedTimer() {
  const N = 5;
  let n = 0;
  const repeatedTimer = common.mustCall(function() {
    if (++n < N)
      setTimeout(repeatedTimer, 1);
    else // n == N
      process.once('beforeExit', common.mustCall(tryNextTickSetImmediate));
  }, N);
  setTimeout(repeatedTimer, 1);
}

// Test if the callback of `process.nextTick` can be invoked.
function tryNextTickSetImmediate() {
  process.nextTick(common.mustCall(function() {
    setImmediate(common.mustCall(() => {
      process.once('beforeExit', common.mustCall(tryNextTick));
    }));
  }));
}

// Test that `process.nextTick` won't keep the event loop running by itself.
function tryNextTick() {
  process.nextTick(common.mustCall(function() {
    process.once('beforeExit', common.mustNotCall());
  }));
}