few changes suggested by fred.

theano/sandbox/cuda/opt.py

@@ -447,7 +447,7 @@ def local_gpu_dot_to_dot22(node):
     return False
 
 
-@local_optimizer([None])
+@local_optimizer([theano.gof.Op])
 def local_assert_no_cpu_op(node):
     if not isinstance(node.op, GpuOp) and all([var.owner and isinstance(var.owner.op,
         HostFromGpu) for var in node.inputs]) and all([var.owner and
@@ -461,8 +461,10 @@ def local_assert_no_cpu_op(node):
                 pdb.set_trace()
     return None
 
-if config.assert_no_cpu_op != "ignore":
-    register_opt()(local_assert_no_cpu_op)
+#Register the local_assert_no_cpu_op:
+assert_no_cpu_op = theano.tensor.opt.in2out(local_assert_no_cpu_op, name='assert_no_cpu_op')
+# 48.7 is after specialize device
+theano.compile.optdb.register('assert_no_cpu_op', assert_no_cpu_op, 48.7)
 
 
 @register_opt()

theano/sandbox/cuda/tests/test_opt.py

@@ -92,17 +92,23 @@ def test_local_gpu_contiguous_gpu_contiguous():
 
 
 def test_local_assert_no_cpu_op():
+    #opt.assert_no_cpu_op = "raise"
     numpy.random.seed(1)
-    m = np.random.uniform(-1, 1, (10, 10)).astype("float32")
+    m = numpy.random.uniform(-1, 1, (10, 10)).astype("float32")
     ms = theano.shared(m, name="m_shared")
     z = ms**2 + 3
-    mode_local_assert = mode_with_gpu.including("local_assert_no_cpu_op")
-    mode_local_assert = mode_local_assert.excluding("local_gpu_elemwise_1")
 
-    f = theano.function([], z, mode=mode_local_assert)
-    topo = f.maker.fgraph.toposort()
-    a_op = [n for n in topo if not isinstance(n.op, cuda.GpuElemwise)]
-    assert len(a_op) == 3
+    def perform_assert_no_cpu_test(out, flag="ignore"):
+
+        mode_local_assert = mode_with_gpu.including("local_assert_no_cpu_op")
+        mode_local_assert = mode_local_assert.excluding("local_gpu_elemwise_1")
+        #If the flag is raise
+        try:
+            mode_local_assert = \
+                    mode_local_assert.including("assert_no_cpu_op='%s'" % flag)
+            f = theano.function([], out, mode=mode_local_assert)
+        except Exception as expt:
+            #If the flag is ignore
 
 
 def test_int_pow():