failing test case as starter

Signed-off-by: Masaki Kozuki <mkozuki@nvidia.com>

thunder/tests/test_tensor_subclass.py

@@ -1,14 +1,18 @@
 from __future__ import annotations
 from typing import TYPE_CHECKING
 
+import pytest
 import torch
+from torch.utils import _pytree as pytree
 
 import thunder
-from thunder.tests.framework import instantiate, NOTHING
+from thunder.core.proxies import SubclassTensorProxy
+from thunder.tests.framework import instantiate, nvFuserExecutor
 from thunder.tests.make_tensor import make_tensor
 
 if TYPE_CHECKING:
     from typing import Any
+    from thunder.core.symbol import BoundSymbol
 
 
 class ScaleTensorSubclass(torch.Tensor):
@@ -118,3 +122,41 @@ def f(x: torch.Tensor, scale: torch.Tensor):
     expected = f(x, scale)
     actual = jitted(x, scale)
     torch.testing.assert_close((expected._x, expected._scale), (actual._x, actual._scale))
+
+
+@instantiate(
+    dtypes=(thunder.core.dtypes.float32,),
+)
+def test_func_of_subclass_simple_math(executor, device, _):
+
+    def f(x: ScaleTensorSubclass, data: torch.Tensor, scale: torch.Tensor) -> ScaleTensorSubclass:
+
+        y = ScaleTensorSubclass(data, scale)
+        out = x + y
+        return out
+
+    jitted = executor.make_callable(f)
+
+    dtype = torch.float32
+    shape = (2, 2)
+    x = ScaleTensorSubclass(
+        make_tensor(shape, device=device, dtype=dtype),
+        make_tensor((), device=device, dtype=dtype),
+    )
+    data = make_tensor(shape, device=device, dtype=dtype)
+    scale = make_tensor((), device=device, dtype=dtype)
+
+    expected = f(x, data, scale)
+    actual = jitted(x, data, scale)
+    if executor == nvFuserExecutor:
+        with pytest.raises(Exception):
+            assert type(expected) is type(actual)
+            torch.testing.assert_close((expected._x, expected._scale), (actual._x, actual._scale))
+    else:
+        assert type(expected) is type(actual)
+        torch.testing.assert_close((expected._x, expected._scale), (actual._x, actual._scale))
+
+    return_bsym: BoundSymbol = thunder.last_traces(jitted)[-1].bound_symbols[-1]
+    return_proxy = return_bsym.flat_args[0]
+    # FIXME(crcrpar): Implement a trace transform that corrects the output type of bsyms involving tensor subclasses
+    assert not isinstance(return_proxy, SubclassTensorProxy)