new file mode 100755
--- /dev/null
+++ b/tests/test-debugindexdot
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+# Just exercize debugindexdot
+# Create a short file history including a merge.
+hg init t
+cd t
+echo a > a
+hg ci -qAm t1 -d '0 0'
+echo a >> a
+hg ci -m t2 -d '1 0'
+hg up -qC 0
+echo b >> a
+hg ci -m t3 -d '2 0'
+HGMERGE=true hg merge -q
+hg ci -m merge -d '3 0'
+
+hg debugindexdot .hg/store/data/a.i

new file mode 100644
--- /dev/null
+++ b/tests/test-debugindexdot.out
@@ -0,0 +1,7 @@
+digraph G {
+	-1 -> 0
+	0 -> 1
+	0 -> 2
+	2 -> 3
+	1 -> 3
+}