### Question:
TreeViewBranchAdapter implements GriffonPivotAdapter, org.apache.pivot.wtk.TreeViewBranchListener { public void branchExpanded(org.apache.pivot.wtk.TreeView arg0, org.apache.pivot.collections.Sequence.Tree.Path arg1) { if (branchExpanded != null) { branchExpanded.call(arg0, arg1); } }  CallableWithArgs<Void> getBranchExpanded(); CallableWithArgs<Void> getBranchCollapsed(); void setBranchExpanded(CallableWithArgs<Void> branchExpanded); void setBranchCollapsed(CallableWithArgs<Void> branchCollapsed); void branchExpanded(org.apache.pivot.wtk.TreeView arg0, org.apache.pivot.collections.Sequence.Tree.Path arg1); void branchCollapsed(org.apache.pivot.wtk.TreeView arg0, org.apache.pivot.collections.Sequence.Tree.Path arg1);  }### Answer:
@Test public void testBranchExpanded() { final boolean[] invoked = new boolean[1]; CallableWithArgs<Void> callable = new CallableWithArgs<Void>() { public Void call(Object... args) { invoked[0] = true; return null; } }; assertNull(adapter.getBranchExpanded()); adapter.branchExpanded(null, null); assertFalse(invoked[0]); adapter.setBranchExpanded(callable); adapter.branchExpanded(null, null); assertTrue(invoked[0]); }