tests: shell: restore element expiration

This patch adds a test for 24f33c710e8c ("src: enable set expiration
date for set elements").

This is also implicitly testing for a cache corruption bug that is fixed
by 9b032cd6477b ("monitor: fix double cache update with --echo").

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/tests/shell/testcases/sets/0036add_set_element_expiration_0 b/tests/shell/testcases/sets/0036add_set_element_expiration_0
new file mode 100755 (executable)
index 0000000..710cf5a
--- /dev/null
+++ b/tests/shell/testcases/sets/0036add_set_element_expiration_0
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+NFT=nft
+
+set -e
+
+RULESET="add table ip x
+add set ip x y { type ipv4_addr; flags dynamic,timeout; } 
+add element ip x y { 1.1.1.1 timeout 30s expires 15s }"
+
+test_output=$($NFT -e -f - <<< "$RULESET" 2>&1)
+
+diff -u <(echo "$test_output") <(echo "$RULESET")