--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-check-format.t	Mon Oct 07 11:52:58 2019 -0400
@@ -0,0 +1,7 @@
+#require grey
+
+(this should use the actual black as soon as possible)
+
+  $ cd $RUNTESTDIR/..
+  $ python3 contrib/grey.py -S --quiet --check --diff `hg files 'set:**.py - hgext/fsmonitor/pywatchman/** - mercurial/thirdparty/** - "contrib/python-zstandard/**" - contrib/grey.py'`
+