test, win32: fix up symlink tests

test/README.md

@@ -163,6 +163,13 @@ A stream to push an array into a REPL
 
 Blocks for `time` amount of time.
 
+### canCreateSymLink
+API to indicate whether the current running process can create
+symlinks. On Windows, this returns false if the process running
+doesn't have privileges to create symlinks (specifically 
+[SeCreateSymbolicLinkPrivilege](https://msdn.microsoft.com/en-us/library/windows/desktop/bb530716(v=vs.85).aspx)). 
+On non-Windows platforms, this currently returns true.
+
 ### ddCommand(filename, kilobytes)
 * return [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)
 

test/common.js

@@ -9,6 +9,7 @@ const stream = require('stream');
 const buffer = require('buffer');
 const util = require('util');
 const Timer = process.binding('timer_wrap').Timer;
+const execSync = require('child_process').execSync;
 
 const testRoot = process.env.NODE_TEST_DIR ?
                    path.resolve(process.env.NODE_TEST_DIR) : __dirname;
@@ -460,6 +461,34 @@ exports.fileExists = function(pathname) {
   }
 };
 
+exports.canCreateSymLink = function() {
+  // On Windows, creating symlinks requires admin privileges.
+  // We'll only try to run symlink test if we have enough privileges.
+  // On other platforms, creating symlinks shouldn't need admin privileges
+  if (exports.isWindows) {
+    // whoami.exe needs to be the one from System32
+    // If unix tools are in the path, they can shadow the one we want,
+    // so use the full path while executing whoami
+    const whoamiPath = path.join(process.env['SystemRoot'],
+      'System32', 'whoami.exe');
+
+    let err = false;
+    let output = '';
+
+    try {
+      output = execSync(whoamiPath + ' /priv', { timout: 1000 });
+    } catch (e) {
+      err = true;
+    } finally {
+      if (err || !output.includes('SeCreateSymbolicLinkPrivilege')) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+};
+
 function fail(msg) {
   assert.fail(null, null, msg);
 }

test/parallel/test-fs-options-immutable.js

@@ -29,7 +29,7 @@ common.refreshTmpDir();
   assert.doesNotThrow(() => fs.readdirSync(__dirname, options));
 }
 
-{
+if (common.canCreateSymLink()) {
   const sourceFile = path.resolve(common.tmpDir, 'test-readlink');
   const linkFile = path.resolve(common.tmpDir, 'test-readlink-link');
 

test/parallel/test-fs-symlink.js

@@ -3,20 +3,13 @@ const common = require('../common');
 const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
-const exec = require('child_process').exec;
 
 var linkTime;
 var fileTime;
 
-if (common.isWindows) {
-  // On Windows, creating symlinks requires admin privileges.
-  // We'll only try to run symlink test if we have enough privileges.
-  exec('whoami /priv', function(err, o) {
-    if (err || !o.includes('SeCreateSymbolicLinkPrivilege')) {
-      common.skip('insufficient privileges');
-      return;
-    }
-  });
+if (!common.canCreateSymLink()) {
+  common.skip('insufficient privileges');
+  return;
 }
 
 common.refreshTmpDir();