fix: Tune write access verification on Windows (#340)

lib/helpers.js

@@ -1,5 +1,6 @@
 import path from 'path';
-import { fs } from 'appium-support';
+import { fs, system } from 'appium-support';
+
 
 let helpers = {};
 
@@ -18,8 +19,15 @@ helpers.ensureInternetPermissionForApp = async function (adb, app) {
 helpers.isWriteable = async function isWriteable (filePath) {
   try {
     await fs.access(filePath, fs.W_OK);
+    if (system.isWindows()) {
+      // On operating systems, where access-control policies may
+      // limit access to the file system, `fs.access` does not work
+      // as expected. See https://groups.google.com/forum/#!topic/nodejs/qmZtIwDRSYo
+      // for more details
+      await fs.close(await fs.open(filePath, 'r+'));
+    }
     return true;
-  } catch (e) {
+  } catch (ign) {
     return false;
   }
 };