functests, multus: refactor configInterface to allow sudo

VMs based on Cirros images require sudo to configure the IP
address.

A follow up patch will reuse this function for cirros based VMs.

Signed-off-by: Miguel Duarte Barroso <mdbarroso@redhat.com>

tests/vmi_multus_test.go

@@ -938,23 +938,27 @@ func cidrToIP(cidr string) string {
 	return ip.String()
 }
 
-func configInterface(vmi *v1.VirtualMachineInstance, interfaceName, interfaceAddress string) {
-	cmdCheck := fmt.Sprintf("ip addr add %s dev %s\n", interfaceAddress, interfaceName)
+func configVMIInterfaceWithSudo(vmi *v1.VirtualMachineInstance, interfaceName, interfaceAddress string) {
+	configInterface(vmi, interfaceName, interfaceAddress, "sudo ")
+}
+
+func configInterface(vmi *v1.VirtualMachineInstance, interfaceName, interfaceAddress string, userModifierPrefix ...string) {
+	setStaticIpCmd := fmt.Sprintf("%sip addr add %s dev %s\n", strings.Join(userModifierPrefix, " "), interfaceAddress, interfaceName)
 	err := console.SafeExpectBatch(vmi, []expect.Batcher{
 		&expect.BSnd{S: "\n"},
 		&expect.BExp{R: console.PromptExpression},
-		&expect.BSnd{S: cmdCheck},
+		&expect.BSnd{S: setStaticIpCmd},
 		&expect.BExp{R: console.PromptExpression},
 		&expect.BSnd{S: "echo $?\n"},
 		&expect.BExp{R: console.RetValue("0")},
 	}, 15)
 	Expect(err).ToNot(HaveOccurred(), "Failed to configure address %s for interface %s on VMI %s", interfaceAddress, interfaceName, vmi.Name)
 
-	cmdCheck = fmt.Sprintf("ip link set %s up\n", interfaceName)
+	setIfaceUpCmd := fmt.Sprintf("ip link set %s up\n", interfaceName)
 	err = console.SafeExpectBatch(vmi, []expect.Batcher{
 		&expect.BSnd{S: "\n"},
 		&expect.BExp{R: console.PromptExpression},
-		&expect.BSnd{S: cmdCheck},
+		&expect.BSnd{S: setIfaceUpCmd},
 		&expect.BExp{R: console.PromptExpression},
 		&expect.BSnd{S: "echo $?\n"},
 		&expect.BExp{R: console.RetValue("0")},