port parallel tests

package.json

@@ -5,7 +5,7 @@
   "license": "MIT",
   "repository": "juliangruber/node-core-test",
   "scripts": {
-    "test": "prettier-standard && standard && node test"
+    "test": "prettier-standard && standard && node test && node test/parallel/test-runner-exit-code"
   },
   "devDependencies": {
     "prettier-standard": "^16.4.1",

test/parallel/test-runner-exit-code.js

@@ -0,0 +1,29 @@
+'use strict'
+
+// https://github.com/cjihrig/node/blob/527eb5caa5feae3b748d9c5b74b256edbb40a775/test/parallel/test-runner-exit-code.js
+
+const assert = require('assert')
+const { spawnSync } = require('child_process')
+
+if (process.argv[2] === 'child') {
+  const test = require('../..')
+
+  if (process.argv[3] === 'pass') {
+    test('passing test', () => {
+      assert.strictEqual(true, true)
+    })
+  } else {
+    assert.strictEqual(process.argv[3], 'fail')
+    test('failing test', () => {
+      assert.strictEqual(true, false)
+    })
+  }
+} else {
+  let child = spawnSync(process.execPath, [__filename, 'child', 'pass'])
+  assert.strictEqual(child.status, 0)
+  assert.strictEqual(child.signal, null)
+
+  child = spawnSync(process.execPath, [__filename, 'child', 'fail'])
+  assert.strictEqual(child.status, 1)
+  assert.strictEqual(child.signal, null)
+}