improved test

theano/scan_module/tests/test_scan.py

@@ -2519,18 +2519,40 @@ class T_Scan(unittest.TestCase):
         out = f(vx)
         assert out == 24
 
+    def test_infershape_seq_shorter_nsteps(self):
+        raise KnownFailureTest('This is a generic problem with infershape'
+                               ' that has to be discussed and figured out')
+        x = tensor.vector('x')
+        [o1, o2], _ = theano.scan(lambda x,y: (x+1, y+x),
+                         sequences = x,
+                         outputs_info = [None, x[0]],
+                         n_steps = 20)
+
+        f = theano.function([x], [o1.shape[0], o2.shape[0]], mode = mode_with_opt)
+
+        vx = numpy.ones((10,), dtype = theano.config.floatX)
+        out1, out2 = f(vx)
+        assert out1 == 10
+        assert out2 == 10
+        lssc = [x for x in f.maker.env.toposort()
+                if isinstance(x.op, theano.scan_module.scan_op.Scan)]
+        assert len(lssc) == 0
+
+
     def test_infershape_nsteps_smaller_seq_length(self):
         x = tensor.vector('x')
-        o, _ = theano.scan(lambda x: x+1,
+        [o1, o2], _ = theano.scan(lambda x, y: (x+1, y+x),
                          sequences = x,
-                         outputs_info = [None],
+                         outputs_info = [None, x[0]],
                          n_steps = 20)
 
-        f = theano.function([x], o.shape[0], mode = mode_with_opt)
+        f = theano.function([x], [o1.shape[0], o2.shape[0]],
+                            mode = mode_with_opt)
 
         vx = numpy.ones((30,), dtype = theano.config.floatX)
-        out = f(vx)
-        assert out == 20
+        o1, o2 = f(vx)
+        assert o1 == 20
+        assert o2 == 20
         lssc = [x for x in f.maker.env.toposort()
                 if isinstance(x.op, theano.scan_module.scan_op.Scan)]
         assert len(lssc) == 0