Ex1 ex1 = new Ex1();
ex1.setStringAsString("Hello");
ex1.setValue(100);
in.add(ex1);
boolean result = tester.runFlow(new TwinCogroupStage(in.flow(), out.flow()));
assertThat(result, is(true));
List<Ex1> outputs = out.toList();
assertThat(outputs.size(), is(1));
assertThat(outputs.get(0).getValue(), is(200));