diff --git a/tests/test-dispatch.out b/tests/test-dispatch.out
--- a/tests/test-dispatch.out
+++ b/tests/test-dispatch.out
@@ -1,4 +1,30 @@
 adding a
+# missing arg
+hg cat: invalid arguments
+hg cat [OPTION]... FILE...
+
+output the current or given revision of files
+
+    Print the specified files as they were at the given revision.
+    If no revision is given, the parent of the working directory is used,
+    or tip if no revision is checked out.
+
+    Output may be to a file, in which case the name of the file is
+    given using a format string.  The formatting rules are the same as
+    for the export command, with the following additions:
+
+    %s   basename of file being printed
+    %d   dirname of file being printed, or '.' if in repo root
+    %p   root-relative path name of file being printed
+
+options:
+
+ -o --output   print output to file with formatted name
+ -r --rev      print the given revision
+ -I --include  include names matching the given patterns
+ -X --exclude  exclude names matching the given patterns
+
+use "hg -v help cat" to show global options
 % [defaults]
 a
 a