Follow up "Fix up userdata argument to rebuild"

This patch is a follow-up patch for
I9752d849aa0e6cf608db0def3ca89565cff4debc.

* Add checking a message of an exception in the unit test
* Add 'with' statement when opening a file
* Fix descriptions in the release note

Change-Id: I2c399490f320a202b41a8f8d36710a36621c4853

novaclient/tests/unit/v2/test_shell.py

@@ -1773,8 +1773,11 @@ class ShellTest(utils.TestCase):
                                     'no_such_file')
         cmd = ('rebuild sample-server %s --user-data %s'
                % (FAKE_UUID_1, invalid_file))
-        self.assertRaises(exceptions.CommandError, self.run_command, cmd,
+        ex = self.assertRaises(exceptions.CommandError, self.run_command, cmd,
                                api_version='2.57')
+        self.assertIn("Can't open '%(user_data)s': "
+                      "[Errno 2] No such file or directory: '%(user_data)s'" %
+                      {'user_data': invalid_file}, six.text_type(ex))
 
     def test_rebuild_unset_user_data(self):
         self.run_command('rebuild sample-server %s --user-data-unset' %

novaclient/v2/shell.py

@@ -398,7 +398,8 @@ def _boot(cs, args):
         for f in args.files:
             try:
                 dst, src = f.split('=', 1)
-                files[dst] = open(src)
+                with open(src) as fo:
+                    files[dst] = fo.read()
             except IOError as e:
                 raise exceptions.CommandError(
                     _("Can't open '%(src)s': %(exc)s") %
@@ -416,7 +417,8 @@ def _boot(cs, args):
 
     if args.user_data:
         try:
-            userdata = open(args.user_data)
+            with open(args.user_data) as f:
+                userdata = f.read()
         except IOError as e:
             raise exceptions.CommandError(_("Can't open '%(user_data)s': "
                                             "%(exc)s") %
@@ -1916,7 +1918,8 @@ def do_rebuild(cs, args):
                       "'--user-data'."))
         elif args.user_data:
             try:
-                kwargs['userdata'] = open(args.user_data)
+                with open(args.user_data) as f:
+                    kwargs['userdata'] = f.read()
             except IOError as e:
                 raise exceptions.CommandError(
                     _("Can't open '%(user_data)s': %(exc)s") % {

releasenotes/notes/fix-rebuild-userdata-9315e5784feb8ba9.yaml

@@ -1,5 +1,6 @@
 ---
 fixes:
   - |
-    The user data argument to rebuild was passing the filename as is as userdata.
-    Now this passes the contents of the filename as intended.
+    The user data argument in the ``nova rebuild`` command was passing
+    the filename as userdata. Now this passes the contents of the file
+    as intended.