diff -r bde505f47141 -r 61151f429a5f tests/test-merge-tools.t
--- a/tests/test-merge-tools.t	Fri May 02 01:09:14 2014 +0200
+++ b/tests/test-merge-tools.t	Mon May 19 01:53:34 2014 +0200
@@ -587,6 +587,54 @@
 
   $ unset HGMERGE # make sure HGMERGE doesn't interfere with remaining tests
 
+update is a merge ...
+
+  $ beforemerge
+  [merge-tools]
+  false.whatever=
+  true.priority=1
+  true.executable=cat
+  # hg update -C 1
+  $ hg debugsetparent 0
+  $ hg update -r 2
+  merging f
+  revision 1
+  space
+  revision 0
+  space
+  revision 2
+  space
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  $ aftermerge
+  # cat f
+  revision 1
+  space
+  # hg stat
+  M f
+
+update should also have --tool
+
+  $ beforemerge
+  [merge-tools]
+  false.whatever=
+  true.priority=1
+  true.executable=cat
+  # hg update -C 1
+  $ hg debugsetparent 0
+  $ hg update -r 2 --tool false
+  merging f
+  merging f failed!
+  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
+  use 'hg resolve' to retry unresolved file merges
+  [1]
+  $ aftermerge
+  # cat f
+  revision 1
+  space
+  # hg stat
+  M f
+  ? f.orig
+
 Default is silent simplemerge:
 
   $ beforemerge