node/test/parallel/test-vm-sigint-existing-handler.js

'use strict';
const common = require('../common');
if (common.isWindows) {
  // No way to send CTRL_C_EVENT to processes from JS right now.
  common.skip('platform not supported');
}

const assert = require('assert');
const vm = require('vm');
const spawn = require('child_process').spawn;

const methods = [
  'runInThisContext',
  'runInContext'
];

if (process.argv[2] === 'child') {
  const method = process.argv[3];
  assert.ok(method);

  let firstHandlerCalled = 0;
  process.on('SIGINT', common.mustCall(() => {
    firstHandlerCalled++;
    // Handler attached _before_ execution.
  }, 2));

  let onceHandlerCalled = 0;
  process.once('SIGINT', common.mustCall(() => {
    onceHandlerCalled++;
    // Handler attached _before_ execution.
  }));

  const script = `process.send('${method}'); while(true) {}`;
  const args = method === 'runInContext' ?
    [vm.createContext({ process })] :
    [];
  const options = { breakOnSigint: true };

  common.expectsError(
    () => { vm[method](script, ...args, options); },
    {
      code: 'ERR_SCRIPT_EXECUTION_INTERRUPTED',
      message: 'Script execution was interrupted by `SIGINT`'
    });
  assert.strictEqual(firstHandlerCalled, 0);
  assert.strictEqual(onceHandlerCalled, 0);

  // Keep the process alive for a while so that the second SIGINT can be caught.
  const timeout = setTimeout(() => {}, 1000);

  let afterHandlerCalled = 0;

  process.on('SIGINT', common.mustCall(() => {
    // Handler attached _after_ execution.
    if (afterHandlerCalled++ === 0) {
      // The first time it just bounces back to check that the `once()`
      // handler is not called the second time.
      assert.strictEqual(firstHandlerCalled, 1);
      assert.strictEqual(onceHandlerCalled, 1);
      process.send(method);
      return;
    }

    assert.strictEqual(onceHandlerCalled, 1);
    assert.strictEqual(firstHandlerCalled, 2);
    timeout.unref();
  }, 2));

  process.send(method);

  return;
}

for (const method of methods) {
  const child = spawn(process.execPath, [__filename, 'child', method], {
    stdio: [null, 'inherit', 'inherit', 'ipc']
  });

  child.on('message', common.mustCall(() => {
    // First kill() breaks the while(true) loop, second one invokes the real
    // signal handlers.
    process.kill(child.pid, 'SIGINT');
  }, 3));

  child.on('close', common.mustCall((code, signal) => {
    assert.strictEqual(signal, null);
    assert.strictEqual(code, 0);
  }));
}