test: Worker initialization failure test case

Cover the scenario fixed through
nodejs#31621
Unfortunately there is no easy way to test this, in a
cross-platform manner. So the approach is:
 - open a child process with ulimit restriction on file descriptors
 - in the child process, start few workers - more than the fd limit
 - make sure some workers fail, with the expected error type.
 - skip the test in windows, as there is no ulimit there.

test/parallel/test-worker-init-failed.js

@@ -0,0 +1,43 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const child_process = require('child_process');
+
+// Test that workers fail with meaningful error message
+// when their initialization fails.
+
+if (process.argv[2] === 'child') {
+  const {Worker} = require('worker_threads');
+  for (let i = 0; i < 256; ++i) {
+    const worker = new Worker(
+      'require(\'worker_threads\').parentPort.postMessage(2 + 2)',
+      { eval: true });
+    worker.on('message', (result) => {
+      assert.strictEqual(result, 4);
+    })
+    worker.on('error', (e) => {
+      assert(e.message.match(/Worker initialization failure: EMFILE/));
+      assert.strictEqual(e.code, 'ERR_WORKER_INIT_FAILED');
+    })
+  }
+
+} else {
+
+  if (common.isWindows) {
+    common.skip('ulimit does not work on Windows.');
+  }
+
+  // limit the number of open files, to force workers to fail
+  let testCmd = 'ulimit -n 128 && ';
+
+  testCmd += `${process.argv[0]} ${process.argv[1]} child`;
+  const cp = child_process.exec(testCmd);
+
+  // turn on the child streams for debugging purpose
+  cp.stderr.on('data', (d) => {
+    console.log(d.toString());
+  })
+  cp.stdout.on('data', (d) => {
+    console.log(d.toString());
+  })
+}

test/parallel/test-worker-init-failure.js

@@ -0,0 +1,43 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const child_process = require('child_process');
+
+// Test that workers fail with meaningful error message
+// when their initialization fails.
+
+if (process.argv[2] === 'child') {
+  const { Worker } = require('worker_threads');
+  for (let i = 0; i < 256; ++i) {
+    const worker = new Worker(
+      'require(\'worker_threads\').parentPort.postMessage(2 + 2)',
+      { eval: true });
+    worker.on('message', (result) => {
+      assert.strictEqual(result, 4);
+    });
+    worker.on('error', (e) => {
+      assert(e.message.match(/Worker initialization failure: EMFILE/));
+      assert.strictEqual(e.code, 'ERR_WORKER_INIT_FAILED');
+    });
+  }
+
+} else {
+
+  if (common.isWindows) {
+    common.skip('ulimit does not work on Windows.');
+  }
+
+  // Limit the number of open files, to force workers to fail
+  let testCmd = 'ulimit -n 128 && ';
+
+  testCmd += `${process.argv[0]} ${process.argv[1]} child`;
+  const cp = child_process.exec(testCmd);
+
+  // Turn on the child streams for debugging purpose
+  cp.stderr.on('data', (d) => {
+    console.log(d.toString());
+  });
+  cp.stdout.on('data', (d) => {
+    console.log(d.toString());
+  });
+}