tests: client: Add client config test suite

* Test the client configuration to detect breakages

test/config.sh

@@ -9,6 +9,7 @@ imageTests+=(
 	[openvpn]='
 	paranoid
         conf_options
+        client
         basic
         dual-proto
         otp

test/tests/client/container.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+# Function to fail
+abort() { cat <<< "$@" 1>&2; exit 1; }
+
+
+#
+# Generate openvpn.config file
+#
+SERV_IP=$(ip -4 -o addr show scope global  | awk '{print $4}' | sed -e 's:/.*::' | head -n1)
+
+ovpn_genconfig \
+    -u udp://$SERV_IP \
+    -m 1337 \
+
+
+EASYRSA_BATCH=1 EASYRSA_REQ_CN="Travis-CI Test CA" ovpn_initpki nopass
+
+easyrsa build-client-full test1 nopass 2>/dev/null
+
+TEST1_OVPN="/etc/openvpn/test1.ovpn"
+ovpn_getclient test1 > "${TEST1_OVPN}"
+
+# Check a config (haystack) for a given line (needle) exit with error if not found.
+test-client-config() {
+
+    local needle="${1}"
+
+    busybox grep -q "${needle}" "${TEST1_OVPN}"
+    if [ $? -ne 0 ]; then
+        abort "==> Config match not found: ${needle}"
+    fi
+}
+
+#
+# Test cases
+#
+
+# Test 1: Check MTU
+test-client-config "^tun-mtu\s+1337"

test/tests/client/run.sh

@@ -0,0 +1 @@
+../run-bash-in-container.sh