@Test(expected = IOException.class)
public void prepare_invalid_source() throws Exception {
Map<String, String> conf = new HashMap<String, String>();
DriverScript driverScript = new DriverScript("file", conf);
FileResourceMirror resource = new FileResourceMirror(profile(), new ParameterList());
try {
ProcessScript<StringBuilder> a = process("a", driverScript, dummy());
ProcessScript<StringBuilder> b = process("b", dummy(), driver("drain"));
GateScript gate = script(a, b);
resource.prepare(gate);