test/jdk/java/net/SocketPermission/SocketPermissionTest.java question about Optional usage in joinGroupMulticastTest()

[Daniel Fuchs]

Thanks Matthias,

It does look like a bug. We probably have at least one
IPv4 multicast interfaces on all machines in our CI!
Not sure whether randomly selecting the first one is such
a good idea though - we may have to investigate how
stable the test gets if we fix this...

best regards,

-- daniel

On 06/07/2021 13:26, Baesken, Matthias wrote:
> Hi , I wonder about the coding in SocketPermissionTest.java  
> joinGroupMulticastTest() :
> 
> https://github.com/openjdk/jdk/blob/master/test/jdk/java/net/SocketPermission/SocketPermissionTest.java#L224 
> <https://github.com/openjdk/jdk/blob/master/test/jdk/java/net/SocketPermission/SocketPermissionTest.java#L224>
> 
> // Positive ( requires a functional network interface )
> 
>              Optional<NetworkInterface> onif = 
> probe().ip4MulticastInterfaces().findFirst();
> 
>              if (!onif.isPresent()) {
> 
>                  s.setNetworkInterface(onif.get());
> 
> In case of  !onif.isPresent() , we call in the next line  onif get , 
> that leads always to a
> 
> java.util.NoSuchElementException: No value present
> 
>          at java.util.Optional.get(Optional.java:135)
> 
>          at 
> SocketPermissionTest.joinGroupMulticastTest(SocketPermissionTest.java:221)
> 
> Is this really intended ?   Should it  be  if (onif.isPresent()) {..}    ?
> 
> Best regards, Matthias
>