test: fix defect path traversal tests

The test never actually tested what it claims to test because it did not
properly insert separators before `..`.

Author: tniessen

test/fixtures/permission/fs-traversal.js

@@ -8,9 +8,9 @@ const path = require('path');
 
 const blockedFolder = process.env.BLOCKEDFOLDER;
 const allowedFolder = process.env.ALLOWEDFOLDER;
-const traversalPath = allowedFolder + '../file.md';
-const traversalFolderPath = allowedFolder + '../folder';
-const bufferTraversalPath = Buffer.from(allowedFolder + '../file.md');
+const traversalPath = allowedFolder + '/../file.md';
+const traversalFolderPath = allowedFolder + '/../folder';
+const bufferTraversalPath = Buffer.from(allowedFolder + '/../file.md');
 
 {
   assert.ok(process.permission.has('fs.read', allowedFolder));

test/parallel/test-permission-fs-traversal-path.js

@@ -18,7 +18,7 @@ const tmpdir = require('../common/tmpdir');
 
 const file = fixtures.path('permission', 'fs-traversal.js');
 const blockedFolder = tmpdir.path;
-const allowedFolder = tmpdir.resolve('subdirectory/');
+const allowedFolder = tmpdir.resolve('subdirectory');
 const commonPathWildcard = path.join(__filename, '../../common*');
 
 {