A smoke test for WEAVE_NO_FASTDP

Partly for the side effect of restoring coverage of
router/ethernet_decoder.go

test/190_no_fastdp.sh

@@ -0,0 +1,26 @@
+#! /bin/bash
+
+. ./config.sh
+
+C1=10.2.1.46
+C2=10.2.1.47
+
+start_suite "WEAVE_NO_FASTDP operation"
+
+weave_on $HOST1 launch
+weave_on $HOST2 launch
+
+start_container $HOST1 $C1/24 --name=c1
+start_container $HOST2 $C2/24 --name=c2
+
+# Without fastdp, ethwe should have an MTU of 65535
+assert_raises "exec_on $HOST1 c1 sh -c 'ip link show ethwe | grep \ mtu\ 65535\ >/dev/null'"
+
+# Pump some data over a TCP socket between the containers.  This
+# should cause PMTU discovery on the overlay network, and hence cause
+# weave to generate an ICMP frag-needed
+assert_raises "exec_on $HOST1 c1 sh -c 'nc -l -p 5555 >/tmp/foo &'"
+assert_raises "exec_on $HOST2 c2 sh -c 'dd if=/dev/zero bs=10k count=1 | nc $C1 5555'"
+assert_raises "exec_on $HOST1 c1 sh -c 'test \$(stat -c %s /tmp/foo) -eq 10240'"
+
+end_suite