diff --git a/tests/test-check-config.t b/tests/test-check-config.t
--- a/tests/test-check-config.t
+++ b/tests/test-check-config.t
@@ -1,8 +1,34 @@
 #require test-repo
 
   $ . "$TESTDIR/helpers-testrepo.sh"
+
+Sanity check check-config.py
+
+  $ cat > testfile.py << EOF
+  > # Good
+  > foo = ui.config('ui', 'username')
+  > # Missing
+  > foo = ui.config('ui', 'doesnotexist')
+  > # Missing different type
+  > foo = ui.configint('ui', 'missingint')
+  > # Missing with default value
+  > foo = ui.configbool('ui', 'missingbool1', default=True)
+  > foo = ui.configbool('ui', 'missingbool2', False)
+  > EOF
+
+  $ cat > files << EOF
+  > mercurial/help/config.txt
+  > $TESTTMP/testfile.py
+  > EOF
+
   $ cd "$TESTDIR"/..
 
+  $ python contrib/check-config.py < $TESTTMP/files
+  undocumented: ui.doesnotexist (str)
+  undocumented: ui.missingbool1 (bool) [True]
+  undocumented: ui.missingbool2 (bool)
+  undocumented: ui.missingint (int)
+
 New errors are not allowed. Warnings are strongly discouraged.
 
   $ hg files "set:(**.py or **.txt) - tests/**" | sed 's|\\|/|g' |