add the integration test for file discovery

Signed-off-by: Chanwit Kaewkasi <chanwit@gmail.com>

test/integration/file-discovery.bats

@@ -0,0 +1,28 @@
+#!/usr/bin/env bats
+
+load helpers
+
+# create a blank temp file for discovery
+DISCOVERY_FILE=$(mktemp)
+
+function teardown() {
+	swarm_manage_cleanup
+	rm -f $DISCOVERY_FILE
+	stop_docker
+}
+
+function setup_file_discovery() {
+	for host in ${HOSTS[@]}; do
+		echo "$host" >> $DISCOVERY_FILE
+	done
+}
+
+@test "docker info should return the number of nodes with file discovery" {
+	start_docker 2
+	setup_file_discovery
+	swarm_manage file://$DISCOVERY_FILE
+
+	run docker_swarm info
+	[ "$status" -eq 0 ]
+	[[ "${lines[3]}" == *"Nodes: 2" ]]
+}