private String signalListenerForSignalCannotBeNullErrorMessage(Signal signal) {
    return String.format(
        "The SignalListener being registered to listen for '%1$s' signals cannot be null!",
        signal.getName());
  }
Unit tests for {@link AbstractSignalNotificationHandler}.

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