test: replaces fixturesDir with fixtures

PR-URL: #15838
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

test/parallel/test-inspector-invalid-args.js

@@ -1,24 +1,27 @@
 'use strict';
 const common = require('../common');
+const fixtures = require('../common/fixtures');
 
 common.skipIfInspectorDisabled();
 
 const assert = require('assert');
 const execFile = require('child_process').execFile;
-const path = require('path');
 
-const mainScript = path.join(common.fixturesDir, 'loop.js');
+const mainScript = fixtures.path('loop.js');
 const expected =
   '`node --debug` and `node --debug-brk` are invalid. ' +
   'Please use `node --inspect` or `node --inspect-brk` instead.';
 for (const invalidArg of ['--debug-brk', '--debug']) {
   execFile(
     process.execPath,
-    [ invalidArg, mainScript ],
+    [invalidArg, mainScript],
     common.mustCall((error, stdout, stderr) => {
       assert.strictEqual(error.code, 9, `node ${invalidArg} should exit 9`);
-      assert.strictEqual(stderr.includes(expected), true,
-                         `${stderr} should include '${expected}'`);
+      assert.strictEqual(
+        stderr.includes(expected),
+        true,
+        `${stderr} should include '${expected}'`
+      );
     })
   );
 }