'Test matching sister nodes in a tree.'

def test_rel_sister_nodes(self):

    tree = ParentedTree.fromstring(u'(S    (A    x)    (B    x)    (C    x))')
    self.assertEqual(list(tgrep.tgrep_positions(u'*    $.    B', [tree])), [[(0,)]])
    self.assertEqual(list(tgrep.tgrep_positions(u'*    $..    B', [tree])), [[(0,)]])
    self.assertEqual(list(tgrep.tgrep_positions(u'*    $,    B', [tree])), [[(2,)]])
    self.assertEqual(list(tgrep.tgrep_positions(u'*    $,,    B', [tree])), [[(2,)]])
    self.assertEqual(list(tgrep.tgrep_positions(u'*    $    B', [tree])), [[(0,), (2,)]])
