tests: add tests for use dhcp variant

tests/fixtures/use-dhcp-eth0.interfaces

@@ -0,0 +1,3 @@
+auto eth0
+iface eth0
+	use dhcp

tests/ifdown_test

@@ -9,6 +9,7 @@ tests_init \
 	static_ipv4 \
 	static_ipv6 \
 	inet_dhcp \
+	use_dhcp \
 	alias_eth0_home \
 	alias_eth0_work \
 	bonded_bridge
@@ -59,6 +60,14 @@ inet_dhcp_body() {
 		ifdown -S/dev/null -i $FIXTURES/dhcp-eth0.interfaces -n -a
 }
 
+use_dhcp_body() {
+	atf_check -s exit:0 -e ignore \
+		-o match:'ip link set down dev lo' \
+		-o match:'ip link set down dev eth0' \
+		-o match:'dhc' \
+		ifdown -S/dev/null -i $FIXTURES/use-dhcp-eth0.interfaces -n -a
+}
+
 alias_eth0_home_body() {
 	atf_check -s exit:0 -e ignore \
 		-o match:'ip link set down dev wlan0' \

tests/ifquery_test

@@ -9,6 +9,7 @@ tests_init \
 	static_ipv4 \
 	static_ipv6 \
 	dhcp_ipv4 \
+	use_dhcp \
 	state_query_home \
 	state_query_work \
 	state_print
@@ -47,6 +48,11 @@ dhcp_ipv4_body() {
 		  ifquery -S/dev/null -i $FIXTURES/dhcp-eth0.interfaces eth0
 }
 
+use_dhcp_body() {
+	atf_check -s exit:0 -o match:"use dhcp" \
+		  ifquery -S/dev/null -i $FIXTURES/use-dhcp-eth0.interfaces eth0
+}
+
 state_query_home_body() {
 	atf_check -s exit:0 -o match:"iface home" \
 		  ifquery -S $FIXTURES/alias-home.ifstate -i $FIXTURES/alias-home-work.interfaces wlan0

tests/ifup_test

@@ -9,6 +9,7 @@ tests_init \
 	static_ipv4 \
 	static_ipv6 \
 	inet_dhcp \
+	use_dhcp \
 	alias_eth0_home \
 	alias_eth0_work \
 	bonded_bridge
@@ -59,6 +60,14 @@ inet_dhcp_body() {
 		ifup -S/dev/null -i $FIXTURES/dhcp-eth0.interfaces -n -a
 }
 
+use_dhcp_body() {
+	atf_check -s exit:0 -e ignore \
+		-o match:'ip link set up dev lo' \
+		-o match:'ip link set up dev eth0' \
+		-o match:'dhc' \
+		ifup -S/dev/null -i $FIXTURES/use-dhcp-eth0.interfaces -n -a
+}
+
 alias_eth0_home_body() {
 	atf_check -s exit:0 -e ignore \
 		-o match:'ip link set up dev wlan0' \