test(ep-cuda): list the cuFFT DFT sync, and check the allowlist's premise (fixes CUDA compile lane)

[justinchuby]

CUDA compile (Linux x86_64) has been red on main since #2080, and every branch cut from it inherits the failure (seen on #2084: job 97720816964). The set difference is exactly one entry:

left  contains "dft.rs::run"
right does not

The sync is legitimate; the omission was the list

#2080's cuFFT DFT kernel drains the compute stream before its metadata upload:

// The metadata prefix belongs to step-scoped workspace and may be
// reused by the next dispatch. Drain the non-blocking compute stream
// before the synchronous default-stream upload so it cannot overwrite
// metadata still consumed by a prior DFT. This host barrier is one
// reason capture remains explicitly unsupported.

and DftKernel::capture_support returns CaptureSupport::unsupported(…). So it qualifies under the contract's own rule — capture-unsupported paths are listed rather than guarded. Added with that justification.

The rest of the PR: the allowlist's premise was never checked

Listing the entry is the whole fix for the red lane. But the allowlist carried its justification in a comment —

// Every entry is a path whose capture_support is explicitly Unsupported, or a dynamically-admitted kernel's fallback path that capture_support rejects.

— and nothing checked it. That makes the list an unconditional escape hatch: a kernel advertising CaptureSupport::Supported with an unguarded .synchronize() is silenced by one line, graph capture breaks, and the suite goes green. That is a worse outcome than the failure the contract exists to catch, because the contract is the only thing looking.

every_allowlisted_file_can_decline_capture turns the sentence into an assertion. Its limit is stated in its own doc comment: it resolves capture_support per file, not per kernel, because function_blocks is a flat scan with no impl awareness. It is a lower bound and says so.

Falsified in both directions

The contract test is a pure source scan, so it reproduces without --features cuda and without a GPU — that is how CI's failure was reproduced here byte-identically before any change.

mutation	result
drop "dft.rs::run" from the list	contract test FAILS with CI's exact left/right sets — the entry is load-bearing
make dft.rs's capture_support return Supported, entry still listed	every_allowlisted_file_can_decline_capture FAILS — not vacuous

The second row is the one worth reading twice: under that mutation the pre-existing contract test still reports ok. That is the silent escape hatch, demonstrated rather than asserted.

Validation

cargo test --locked -p onnx-runtime-ep-cuda --features cuda --test capture_sync_contract   2 passed; 0 failed
cargo clippy --locked -p onnx-runtime-ep-cuda --features cuda --tests -- -D warnings       clean
cargo fmt --all -- --check                                                                 clean

The first is CI's exact command from the failing step. Test-only change; no production source is touched, so nothing here alters kernel behaviour.

Class

Catalogue #1817: a claim carried in prose where a check was available. The allowlist asserted its own entries were reviewed and had no way to be wrong about it.

[justinchuby]

Expect Rust coverage (macOS arm64) to be red on this PR, and it is not caused by anything here — it is #2083's STFT assertion on the radix-2 counter, which Apple targets never reach for n >= 4. It is red on main and on every branch cut from it; #2097 fixes it. This PR touches only crates/onnx-runtime-ep-cuda/tests/capture_sync_contract.rs.

The lane this PR fixes is CUDA compile (Linux x86_64).

— Gaff

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.60%. Comparing base (46478fc) to head (19c1271).
⚠️ Report is 35 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2099      +/-   ##
==========================================
+ Coverage   80.57%   80.60%   +0.02%     
==========================================
  Files         412      428      +16     
  Lines      193684   209225   +15541     
  Branches   193684   209225   +15541     
==========================================
+ Hits       156064   168642   +12578     
- Misses      32136    34889    +2753     
- Partials     5484     5694     +210     

Flag	Coverage Δ
cli-ort-linux	72.51% <ø> (?)
cli-ort-windows	72.10% <ø> (?)
mlas	85.80% <ø> (?)
offline	80.72% <ø> (+0.15%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 76 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.