Add test

theano/scan_module/tests/test_scan.py

@@ -4107,6 +4107,40 @@ class T_Scan(unittest.TestCase):
         f_strict = theano.function([x0_], ret_strict[0][-1])
         result_strict = f_strict(x0)
 
+    def test_monitor_mode(self):
+        # Test that it is possible to pass an instance of MonitorMode
+        # to the inner function
+        k = tensor.iscalar("k")
+        A = tensor.vector("A")
+
+        # Build a MonitorMode that counts how many values are greater than 10
+        def detect_large_outputs(i, node, fn):
+            for output in fn.outputs:
+                if isinstance(output[0], numpy.ndarray):
+                    detect_large_outputs.large_count += (output[0] > 10).sum()
+        detect_large_outputs.large_count = 0
+
+        mode = theano.compile.MonitorMode(post_func=detect_large_outputs)
+
+        # Symbolic description of the result
+        result, updates = theano.scan(
+            fn=lambda prior_result, A: prior_result * A,
+            outputs_info=tensor.ones_like(A),
+            non_sequences=A,
+            n_steps=k,
+            mode=mode)
+
+        final_result = result[-1]
+
+        f = theano.function(inputs=[A, k],
+                            outputs=final_result,
+                            updates=updates)
+        f([2, 3, .1, 0, 1], 4)
+
+        # There should be 3 outputs greater than 10: prior_result[0] at step 3,
+        # and prior_result[1] at steps 2 and 3.
+        assert detect_large_outputs.large_count == 3
+
 
 class ScanGpuTests:
     """ This class defines a number of tests for Scan on GPU as well as a few