[antlr-interest] Are GUnit tests for Tree Pattern matching grammars (filter=true) supported?

[Stanislas Rusinsky]

Hi Antlr's,

I have a tree pattern matching grammar (filter=true) I want to gunit test it

I can't get Gunit to work with it or find an example online: are they known to work together?

The test fails with a 
expected: (attr3 int (MODIFIERS static))
actual: java.lang.NullPointerException

My tree filter works like this (I have omitted the @package headers for readability, but they are correct):
tree grammar treeFilterA;
options{
tokenVocab=myTextGrammar;
ASTLabelType=CommonTree;
output = AST;
filter = true;
}
topdown
: attribute
;
bottomup : ;
attribute
: ^(ATTRIBUTE e=. (MODIFIERS attribute_modifier*)) -> ^(NOTRELEVANTFORTHISEXAMPLE)
 ;
attribute_modifier: 
: 'persisted'
| 'final'
| 'volatile'
...
;

if I try with this .gunit test:
gunit treeFilterA walks myTextGrammar;
attribute walks attribute:
"static int myAttr" -> "(attr3 int (MODIFIERS static))"

Any idea?

Thx in advance

Stanislas Herman Rusinsky.