HYDRA-1586 : Add a unit test to check against regression with bifrost…

[lanierd-adsk]

… graph updates

[Copilot]

Pull Request Overview

This PR adds a new unit test to check against regression issues with bifrost graph updates. The test verifies the scene snapshots before and after a bifrost graph update is performed via a MEL command.

• Adds a new test file for bifrost graph regression testing.
• Validates scene changes by comparing pre- and post-update snapshots.

Files not reviewed (2)

• test/lib/mayaUsd/render/mayaToHydra/CMakeLists.txt: Language not supported
• test/testSamples/testBifrost/create_point_instancer_from_usd_file.json: Language not supported

Comments suppressed due to low confidence (2)

test/lib/mayaUsd/render/mayaToHydra/testBifrostGraphUpdate.py:39

• [nitpick] Consider refactoring the long MEL command string into a dedicated variable or breaking it across multiple lines to enhance readability and simplify future maintenance.

mel.eval("vnnNode "|createPointInstancerFromUsdFile|createPointInstancerFromUsdFileShape" "/scatter_points" -setPortDefaultValues "amount" "150";")

test/lib/mayaUsd/render/mayaToHydra/testBifrostGraphUpdate.py:39

• [nitpick] Add an inline comment to clarify the purpose of this MEL command, which updates the bifrost graph, for the benefit of future maintainers.

mel.eval("vnnNode "|createPointInstancerFromUsdFile|createPointInstancerFromUsdFileShape" "/scatter_points" -setPortDefaultValues "amount" "150";")