Test a source crashing after an entrust.

This adds a test for destination behaviour, in that if a source crashes
after sending an entrust message but before the destination can reply,
the destination must allow the source to reconnect and retry the mirror.

tests/acceptance/fakes/source/close_after_entrust.rb

@@ -0,0 +1,34 @@
+#!/usr/bin/env ruby
+
+# Connect, send a migration, entrust then *immediately* disconnect.
+# This simulates a client which fails while the client is blocked.
+#
+# We attempt to reconnect immediately afterwards to prove that we can
+# retry the mirroring.
+
+require 'flexnbd/fake_source'
+include FlexNBD
+
+addr, port, srv_pid = *ARGV
+
+client = FakeSource.new( addr, port, "Timed out connecting" )
+client.read_hello
+client.write_write_request( 0, 8 )
+client.write_data( "12345678" )
+
+# Use system "kill" rather than Process.kill because Process.kill
+# doesn't seem to work
+system "kill -STOP #{srv_pid}"
+
+client.write_entrust_request
+client.close
+
+system "kill -CONT #{srv_pid}"
+
+
+sleep(0.25)
+
+client2 = FakeSource.new( addr, port, "Timed out reconnecting" )
+client2.close
+
+exit(0)

tests/acceptance/fakes/source/close_after_write_data.rb

@@ -27,7 +27,7 @@ Process.kill( "CONT", srv_pid.to_i )
 sleep(0.25)
 
 # ...and can we reconnect?
-client2 = FakeSource.new( addr, port, "Timed out connecting" )
+client2 = FakeSource.new( addr, port, "Timed out reconnecting" )
 client2.close
 
 exit(0)