diff --git a/tests/test-parentrevspec b/tests/test-parentrevspec
new file mode 100755
--- /dev/null
+++ b/tests/test-parentrevspec
@@ -0,0 +1,69 @@
+#!/bin/sh
+
+commit()
+{
+    msg=$1
+    p1=$2
+    p2=$3
+
+    if [ "$p1" ]; then
+	hg up -qC $p1
+    fi
+
+    if [ "$p2" ]; then
+	HGMERGE=true hg merge -q $p2
+    fi
+
+    echo >> foo
+
+    hg commit -d '0 0' -qAm "$msg" foo
+}
+
+hg init repo
+cd repo
+
+echo '[extensions]' > .hg/hgrc
+echo 'hgext.parentrevspec =' >> .hg/hgrc
+
+commit '0: add foo'
+commit '1: change foo 1'
+commit '2: change foo 2a'
+commit '3: change foo 3a'
+commit '4: change foo 2b' 1
+commit '5: merge' 3 4
+commit '6: change foo again'
+
+hg log --template '#rev#:#node|short# #parents#\n'
+echo
+
+lookup()
+{
+    for rev in "$@"; do
+	printf "$rev: "
+	hg id -nr $rev
+    done
+    true
+}
+
+tipnode=`hg id -ir tip`
+
+echo 'should work with tag/branch/node/rev'
+for r in tip default $tipnode 6; do
+    lookup $r^
+done
+echo
+
+echo 'some random lookups'
+lookup 6^^ 6^^^ 6^^^^ 6^^^^^ 6^^^^^^ 6^1 6^2 6^^2 6^1^2 6^^3
+lookup 6~ 6~1 6~2 6~3 6~4 6~5 6~42 6~1^2 6~1^2~2
+echo
+
+echo 'with a tag "6^" pointing to rev 1'
+hg tag -l -r 1 6^
+lookup 6^ 6^1 6~1 6^^
+echo
+
+echo 'with a tag "foo^bar" pointing to rev 2'
+hg tag -l -r 2 foo^bar
+lookup foo^bar foo^bar^
+