@Test
  public void registerListenerWithNullSignalThrowsNullPointerException() {
    assertThatThrownBy(() -> createSignalNotificationHandler()
        .registerListener(mock(SignalListener.class, "SIGALL"), null))
            .isInstanceOf(NullPointerException.class)
            .hasMessage("The signal to register the listener for cannot be null!");
  }
Unit tests for {@link AbstractSignalNotificationHandler}.

@since GemFire 7.0
geode-core/src/test/java/org/apache/geode/internal/process/signal/AbstractSignalNotificationHandlerTest.java