diff -r 5fbf1da938a6 -r b6c051cd1231 tests/test-check-help.t
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-check-help.t	Wed Jan 25 22:39:17 2017 +0900
@@ -0,0 +1,25 @@
+#require test-repo
+
+  $ . "$TESTDIR/helpers-testrepo.sh"
+
+  $ cat <<'EOF' > scanhelptopics.py
+  > from __future__ import absolute_import, print_function
+  > import re
+  > import sys
+  > topics = set()
+  > topicre = re.compile(r':hg:`help ([a-z0-9\-.]+)`')
+  > for fname in sys.argv:
+  >     with open(fname) as f:
+  >         topics.update(m.group(1) for m in topicre.finditer(f.read()))
+  > for s in sorted(topics):
+  >     print(s)
+  > EOF
+
+  $ cd "$TESTDIR"/..
+
+Check if ":hg:`help TOPIC`" is valid:
+(use "xargs -n1 -t" to see which help commands are executed)
+
+  $ hg files 'glob:{hgext,mercurial}/**/*.py' \
+  > | xargs python "$TESTTMP/scanhelptopics.py" \
+  > | xargs -n1 hg help > /dev/null