Add test_empty_outputs for Grad

Author: ValerianRey

tests/unit/autojac/_transform/test_grad.py

@@ -62,6 +62,23 @@ def test_empty_inputs_2():
     assert_tensor_dicts_are_close(gradients, expected_gradients)
 
 
+def test_empty_outputs():
+    """
+    Tests that the Grad transform works correctly when the `outputs` parameter is an empty
+    `Iterable`.
+    """
+
+    a = torch.tensor(1.0, requires_grad=True)
+    input = Gradients({})
+
+    grad = Grad(outputs=[], inputs=[a])
+
+    gradients = grad(input)
+    expected_gradients = {a: torch.zeros_like(a)}
+
+    assert_tensor_dicts_are_close(gradients, expected_gradients)
+
+
 def test_retain_graph():
     """Tests that the `Grad` transform behaves as expected with the `retain_graph` flag."""