[vstest]: use BytesIO for file operations

lguohan · lguohan · commit d2bab10efe05 · 2020-07-19T07:07:38.000Z
this is another py3 fix

Signed-off-by: Guohan Lu &lt;lguohan@gmail.com&gt;
diff --git a/tests/conftest.py b/tests/conftest.py
@@ -421,7 +421,7 @@ def runcmd(self, cmd):
         return (exitcode, out)
 
     def copy_file(self, path, filename):
-        tarstr = io.StringIO()
+        tarstr = io.BytesIO()
         tar = tarfile.open(fileobj=tarstr, mode="w")
         tar.add(filename, os.path.basename(filename))
         tar.close()
