CNA-VGAP-024: METAL's CI lane proves construction, clear/present and capability reporting but no representative 3D pixels

CNA snapshot 009d40f5  ·  Known Issues › Verification gaps  ·  source links pinned to 009d40f5

metal-macos-ci.yml runs only ctest -R '^Metal' (Metal_Smoke, Metal_Capabilities, Metal_PortableHelpers) and the compile-definition tests; no textured, lit or depth-tested 3D output is checked on macOS.

Identifier

CNA-VGAP-024

Category

Verification gap

Subsystem

Testing & evidence

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

The METAL renderer's 3D pipeline (stock effects, depth, textures) on macOS

Expected behaviour

A renderer's 3D path needs at least a pixel check of representative draws on its real platform.

Actual behaviour at TARGET

metal-macos-ci.yml builds a Metal tree on macos-14 and runs ctest -R '^Metal' plus GraphicsRendererCompileDefinitionsTest.*. CMakeLists.txt registers only Metal_PortableHelpers, Metal_Smoke and Metal_Capabilities; Metal_Smoke uploads buffers, clears and presents but issues no draw and reads nothing back, and Metal_PortableHelpers runs host-portable policy tests. The lane once ran six draw-and-readback pixel tests (Metal_PbrEffect_Golden, Metal_SkinnedPbrEffect_Golden, Metal_DrawUserPrimitives_VPC, Metal_SpriteBatch_CustomEffect, Metal_MultipleRenderTargets, Metal_Backbuffer_MSAA). CNA's record of GitHub Actions run 29814126178 says all six read back only the clear colour, and CNA responded by making ReadBackbuffer throw NotSupportedException and no longer registering the dependent tests (metal-renderer.md, METAL-258). None of them is registered at TARGET (the source of one, metal_spritebatch_customeffect_test.cpp, is still in the tree unregistered, CNA-VGAP-050), and the adapted renderer has no recorded macOS run.

Source locations

• .github/workflows/metal-macos-ci.yml — ctest -R '^Metal' step
• modules/renderers/metal/examples/CMakeLists.txt — the three Metal registrations

Evidence

Checked by reading the named sources at 009d40f5; nothing was built or executed for this entry.

Independent re-verification: Checked by reading the named sources at 009d40f5; nothing was built or executed for this entry. The history of the six removed tests is CNA's own record in metal-renderer.md; the workflow logs are not in the tree. A future pixel gate has to read a RenderTarget2D or wait for backbuffer readback to be re-enabled, so the shared backbuffer-reading fixtures cannot simply be registered. The refusal itself is CNA-GAP-013.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

As above; the Metal policy unit tests (MetalPolicyTests.cpp) are host-portable logic checks.

Regression test

Register the shared stock-effect and depth pixel fixtures for METAL and run them in the macOS lane.

Blast radius

Every 3D draw on METAL.

Workaround

No workaround is known.