test: refactor mkdtemp test and added async

This test refactored the original test for mkdtempSync prefix validation
and added the test also for the async function mkdtemp.

PR-URL: nodejs#12080
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

test/parallel/test-fs-mkdtemp-prefix-check.js

@@ -0,0 +1,25 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const fs = require('fs');
+
+const expectedError = /^TypeError: filename prefix is required$/;
+const prefixValues = [undefined, null, 0, true, false, 1, ''];
+
+function fail(value) {
+  assert.throws(
+    () => fs.mkdtempSync(value, {}),
+    expectedError
+  );
+}
+
+function failAsync(value) {
+  assert.throws(
+    () => fs.mkdtemp(value, common.mustNotCall()), expectedError
+  );
+}
+
+prefixValues.forEach((prefixValue) => {
+  fail(prefixValue);
+  failAsync(prefixValue);
+});