The script reads the node MinSupportedSampleRate from the ServerCapabilities, but maybe this node itself does not support this minimum sampling interval.

Possible solution could be to read a static scalar defined node.

Modified script:
function test() {
// read the value of the setting
var item = MonitoredItem.fromNodeIds( new UaNodeId( Identifier.Server_ServerCapabilities_MinSupportedSampleRate ) )[0];
if( !ReadHelper.Execute( { NodesToRead: item } ) ) return( false );
var realValue = item.Value.Value.clone();
// create a subscription
var sub = new Subscription();
if( !CreateSubscriptionHelper.Execute( { Subscription: sub } ) ) return( false );
/* modified begin ****/
// create one monitored item from static scalar nodes
var item1 = MonitoredItem.GetRequiredNodes({ Settings: Settings.ServerTest.NodeIds.Static.AllProfiles.Scalar.NumericSettings, Number: 1 })[0];
if( item1 === undefined || item1 === null ) {
addSkipped( "Static Scalar (numeric)" );
return( false );
}
item1.SamplingInterval = 0;
// now to compare a sampling interval to what is specified
if( CreateMonitoredItemsHelper.Execute( { ItemsToCreate: item1, SubscriptionId: sub } ) ) {
if( realValue.toDouble() !== CreateMonitoredItemsHelper.Response.Results[0].RevisedSamplingInterval) addWarning( "Expected the revised Sampling Interval to match the Server.ServerCapabilities.MinSupportedSampleRate=" + realValue );
DeleteMonitoredItemsHelper.Execute( { ItemsToDelete: item1, SubscriptionId: sub } );
}
/*** modified end *****/
DeleteSubscriptionsHelper.Execute( { SubscriptionIds: sub } );
return( true );
}