test: replace fixtureDir with fixtures.path

PR-URL: #15943
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

test/parallel/test-common.js

@@ -1,8 +1,7 @@
 'use strict';
 const common = require('../common');
+const fixtures = require('../common/fixtures');
 const assert = require('assert');
-
-const {join} = require('path');
 const {execFile} = require('child_process');
 
 common.globalCheck = false;
@@ -37,10 +36,10 @@ fnAtLeast2Called3();
 
 const failFixtures = [
   [
-    join(common.fixturesDir, 'failmustcall1.js'),
+    fixtures.path('failmustcall1.js'),
     'Mismatched <anonymous> function calls. Expected exactly 2, actual 1.'
   ], [
-    join(common.fixturesDir, 'failmustcall2.js'),
+    fixtures.path('failmustcall2.js'),
     'Mismatched <anonymous> function calls. Expected at least 2, actual 1.'
   ]
 ];