Enabled assertions in junit tests.

build-common.xml

@@ -24,7 +24,7 @@
 	</target>
 	<target name='compile'>
 		<mkdir dir='build'/>
-		<javac srcdir='net/sf/briar' destdir='build'
+		<javac srcdir='net/sf/briar' destdir='build' source='1.5'
 			includeantruntime='false'>
 			<classpath>
 				<fileset refid='bundled-jars'/>

test/build.xml

 <project name='test' default='test'>
 	<import file='../build-common.xml'/>
 	<target name='test' depends='depend'>
-		<junit printsummary='on' showoutput='true'>
+		<junit printsummary='on' showoutput='true' fork='yes' forkmode='once'>
+			<assertions>
+				<enable/>
+			</assertions>
 			<classpath>
 				<fileset refid='bundled-jars'/>
 				<fileset refid='test-jars'/>