--- a/tests/test-uncommit.t	Tue Jul 11 12:00:45 2017 +0200
+++ b/tests/test-uncommit.t	Tue Jul 11 11:24:43 2017 +0200
@@ -397,3 +397,64 @@
   date:        Thu Jan 01 00:22:17 1970 +0000
   summary:     to-uncommit
   
+
+test the `hg amend --extract` entry point
+
+  $ hg status --change .
+  M j
+  M o
+  A e
+  A ff
+  A h
+  A k
+  A l
+  R c
+  R f
+  R g
+  R m
+  R n
+  $ hg status
+  M d
+  A aa
+  R b
+  $ hg amend --extract j
+  $ hg status --change .
+  M o
+  A e
+  A ff
+  A h
+  A k
+  A l
+  R c
+  R f
+  R g
+  R m
+  R n
+  $ hg status
+  M d
+  M j
+  A aa
+  R b
+
+(with all)
+
+  $ hg amend --extract --all
+  new changeset is empty
+  (use 'hg prune .' to remove it)
+  $ hg status --change .
+  $ hg status
+  M d
+  M j
+  M o
+  A aa
+  A e
+  A ff
+  A h
+  A k
+  A l
+  R b
+  R c
+  R f
+  R g
+  R m
+  R n