@Test
public void should_carry_signal_through_AND_gate_with_wire_at_left_and_wire_at_right() {

    Circuit circuit = new Circuit("123 -> x\n" +
            "456 -> y\n" +
            "x AND y -> d");
    Optional<SpecificValue> d = circuit.signalOf(new Wire("d"));
    assertThat(d).contains(new SpecificValue(72));
}