t_client.sh: conditionally skip ifconfig+route check

For --dev null or --dev-type af_unix:lwipopenvn tests, there will be
no visible change to ifconfig or route output, so tests will fail
("how can this be?").  Set EXPECT_IFCONFIG4_<n>=- to skip this
check.

(Simply leaving both EXPECT_IFCONFIG* vars empty and using that as
trigger would interfere with the magic from commit df0b00c)

v2: fix string-equal comparison

Change-Id: Iec1953415afb53755488dd44407568e72d28e854
Signed-off-by: Gert Doering <[email protected]>
Acked-by: Frank Lichtenheld <[email protected]>
Message-Id: <[email protected]>
URL: https://www.mail-archive.com/[email protected]/msg29473.html
Signed-off-by: Gert Doering <[email protected]>

tests/t_client.sh.in

@@ -225,6 +225,7 @@ check_ifconfig()
     expect_list="$@"
 
     if [ -z "$expect_list" ] ; then return ; fi
+    if [ "$expect_list" = "-" ] ; then return ; fi
 
     for expect in $expect_list
     do
@@ -404,13 +405,17 @@ do
     output "save ifconfig+route"
     get_ifconfig_route >$LOGDIR/$SUF:ifconfig_route.txt
 
-    output -n "compare pre-openvpn ifconfig+route with current values..."
-    if diff $LOGDIR/$SUF:ifconfig_route_pre.txt \
-	    $LOGDIR/$SUF:ifconfig_route.txt >/dev/null
-    then
-	fail "no differences between ifconfig/route before OpenVPN start and now."
+    if [ "$expect_ifconfig4" = "-" ] ; then
+        output "skip ifconfig+route check"
     else
-	output " OK!\n"
+	output -n "compare pre-openvpn ifconfig+route with current values..."
+	if diff $LOGDIR/$SUF:ifconfig_route_pre.txt \
+		$LOGDIR/$SUF:ifconfig_route.txt >/dev/null
+	then
+	    fail "no differences between ifconfig/route before OpenVPN start and now."
+	else
+	    output " OK!\n"
+	fi
     fi
 
     # post init script needed?