Fix when using compute_test_value option with scan

theano/scan_module/scan_utils.py

@@ -36,7 +36,7 @@ _logger = logging.getLogger('theano.scan_utils')
 def safe_new(x, tag=''):
     """
     Internal function that constructs a new variable from x with the same
-    type, but with a different name ( old name + tag). This function is used
+    type, but with a different name (old name + tag). This function is used
     by gradient, or the R-op to construct new variables for the inputs of
     the inner graph such that there is no interference between the original
     graph and the newly constructed graph.
@@ -58,12 +58,22 @@ def safe_new(x, tag=''):
         try:
             x = tensor.as_tensor_variable(x)
         except TypeError:
-            # This could happend for example for random states, and I really
+            # This could happen for example for random states, and I really
             # want to avoid the convoluted logic that checks for cuda
             # ndarrays
             pass
     nw_x = x.type()
     nw_x.name = nw_name
+    # Preserve test values so that the 'compute_test_value' option can be used.
+    # The test value is deep-copied to ensure there can be no interactions
+    # between test values, due to inplace operations for instance. This may
+    # not be the most efficient memory-wise, though.
+    if theano.config.compute_test_value != 'off':
+        try:
+            nw_x.tag.test_value = copy.deepcopy(gof.op.get_test_value(x))
+        except AttributeError:
+            # This means `x` has no test value.
+            pass
     return nw_x