Add tests for broadcastable pattern of flatten output

theano/tensor/tests/test_basic.py

@@ -5100,6 +5100,31 @@ def test_flatten_outdim2_of_3():
     utt.verify_grad(Flatten(2), [a_val])
 
 
+def test_flatten_broadcastable():
+    # Ensure that the broadcastable pattern of the output is coherent with
+    # that of the input
+
+    inp = TensorType('float64', (False, False, False, False))()
+    out = flatten(inp, outdim=2)
+    assert out.broadcastable == (False, False)
+
+    inp = TensorType('float64', (False, False, False, True))()
+    out = flatten(inp, outdim=2)
+    assert out.broadcastable == (False, False)
+
+    inp = TensorType('float64', (False, True, False, True))()
+    out = flatten(inp, outdim=2)
+    assert out.broadcastable == (False, False)
+
+    inp = TensorType('float64', (False, True, True, True))()
+    out = flatten(inp, outdim=2)
+    assert out.broadcastable == (False, True)
+
+    inp = TensorType('float64', (True, False, True, True))()
+    out = flatten(inp, outdim=3)
+    assert out.broadcastable == (True, False, True)
+
+
 def test_flatten_outdim_invalid():
     a = dmatrix()
     try: