Add unit test for existing ac API behavior

[ailzhang]

Stack from ghstack (oldest at bottom):

• -> Add unit test for existing ac API behavior #244

[ailzhang]

The first PR is just adding a unit test (with claude :P ) to make sure I understand the current behavior 🙏 Any feedback is appreciated!

[xmfan]

this implementation is strange, any issues just using the same joint graph capture frontend as the rest of the repo?

autoparallel/autoparallel/api.py

Lines 301 to 310 in b1c4909

	torch_ir_with_fqn = _export(self.model, inputs)
	# TODO Cna't use fake mode here because it clashes with the user level
	# fake mode. Ideally dynamo should reuse the user level fake mode.
	self.joint_with_descriptors = aot_export_joint_with_descriptors(
	self.stack,
	torch_ir_with_fqn,
	inputs,
	decompositions=decomp_table,
	)
	gm = self.joint_with_descriptors.graph_module

[xmfan]

i think this always gets decomposed away. and if it doesn't, it will mess up your saved node count lol