@Test
public void throwExceptionIfCircuitBreakerIsOpen_throws_CircuitBreakerOpenException_if_circuit_is_OPEN() {

    // given
    Whitebox.setInternalState(cbSpy, "currentState", State.OPEN);
    // when
    Throwable cbExplosion = catchThrowable(cbSpy::throwExceptionIfCircuitBreakerIsOpen);
    // then
    assertThat(cbExplosion).isNotNull();
    assertThat(cbExplosion).isInstanceOf(CircuitBreakerOpenException.class);
    verify(cbSpy, times(0)).scheduleHalfOpenStateTimeout();
}