--- a/tests/test-dispatch.t	Sat Nov 04 20:07:40 2017 +0900
+++ b/tests/test-dispatch.t	Sat Nov 11 12:09:19 2017 +0900
@@ -30,6 +30,18 @@
   (use 'hg cat -h' to show more help)
   [255]
 
+Missing parameter for early option:
+
+  $ hg log -R 2>&1 | grep 'hg log'
+  hg log: option -R requires argument
+  hg log [OPTION]... [FILE]
+  (use 'hg log -h' to show more help)
+
+  $ hg log -R -- 2>&1 | grep 'hg log'
+  hg log: option -R requires argument
+  hg log [OPTION]... [FILE]
+  (use 'hg log -h' to show more help)
+
 [defaults]
 
   $ hg cat a