git cl comment: require explicit --codereview with -i|--issue flag.

R=agable@chromium.org,machenbach@chromium.org
BUG=698236

Change-Id: If79f938e457f176c47badd75f78ed4ecb764ec2d
Reviewed-on: https://chromium-review.googlesource.com/456700
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>

git_cl.py

@@ -4260,8 +4260,9 @@ def CMDcomments(parser, args):
   """Shows or posts review comments for any changelist."""
   parser.add_option('-a', '--add-comment', dest='comment',
                     help='comment to add to an issue')
-  parser.add_option('-i', dest='issue',
-                    help='review issue id (defaults to current issue)')
+  parser.add_option('-i', '--issue', dest='issue',
+                    help='review issue id (defaults to current issue). '
+                         'If given, requires --rietveld or --gerrit')
   parser.add_option('-j', '--json-file',
                     help='File to write JSON summary to')
   auth.add_auth_options(parser)
@@ -4276,6 +4277,8 @@ def CMDcomments(parser, args):
       issue = int(options.issue)
     except ValueError:
       DieWithError('A review issue id is expected to be a number')
+    if not options.forced_codereview:
+      parser.error('--gerrit or --rietveld is required if --issue is specified')
 
   cl = Changelist(issue=issue,
                   # TODO(tandrii): remove 'rietveld' default.

tests/git_cl_test.py

@@ -3090,7 +3090,7 @@ class TestGitCl(TestCase):
         sys.stdout.getvalue(),
         'However, your configured .gitcookies file is missing.')
 
-  def test_git_cl_comment_add_default(self):
+  def test_git_cl_comment_add_rietveld(self):
     self.mock(git_cl._RietveldChangelistImpl, 'AddComment',
               lambda _, message: self._mocked_call('AddComment', message))
     self.calls = [
@@ -3098,8 +3098,8 @@ class TestGitCl(TestCase):
       ((['git', 'config', 'rietveld.server'],), 'codereview.chromium.org'),
       (('AddComment', 'msg'), ''),
     ]
-    # TODO(tandrii): --rietveld should be specified here.
-    self.assertEqual(0, git_cl.main(['comment', '-i', '10', '-a', 'msg']))
+    self.assertEqual(0, git_cl.main(['comment', '--rietveld',
+                                     '-i', '10', '-a', 'msg']))
 
   def test_git_cl_comment_add_gerrit(self):
     self.mock(git_cl.gerrit_util, 'SetReview',