new file mode 100755
--- /dev/null
+++ b/tests/test-add
@@ -0,0 +1,42 @@
+#!/bin/sh
+
+hg init a
+cd a
+echo a > a
+hg add -n
+hg st
+hg add
+hg st
+
+echo b > b
+hg add -n b
+hg st
+hg add b
+hg st
+echo % should fail
+hg add b
+hg st
+
+hg ci -m 0
+echo % should fail
+hg add a
+
+echo aa > a
+hg ci -m 1
+hg up 0
+echo aaa > a
+hg ci -m 2
+
+hg merge
+hg st
+echo % should fail
+hg add a
+hg st
+hg ci -m merge
+
+echo % issue683
+hg rm a
+hg st
+echo a > a
+hg add a
+hg st