mark a test as know failure

theano/tensor/nnet/tests/test_nnet.py

@@ -9,7 +9,7 @@ from theano.tensor.tests import test_basic as TT
 from theano import printing
 
 from theano.tensor.nnet import *
-
+from numpy.testing import dec
 
 class T_sigmoid(unittest.TestCase):
     def setUp(self):
@@ -924,6 +924,8 @@ class Test_softmax_opt():
         assert softmax in f_ops
         f(self.rng.rand(3,4))
 
+    @dec.knownfailureif(True,
+                        "This case is not implemented")
     def test_grad(self):
         c = T.matrix()
         p_y = T.exp(c) / T.exp(c).sum(axis=1).dimshuffle(0,'x')