[TRTLLM-9295][fix] restore greedy sampling in _test_openai_chat_guided_decoding

[ixlmar]

Description

Under certain conditions (FlashInfer.sampling is enabled), one of the A10 stages in CI fails. The failure could not be reproduced on A10 outside of CI.

The issue was therefore debugged through CI runs in #9139, revealing that the unit generates <functionrbct=get_current_date>{"timezone": "America/New_York"}/function>\n<functionrbct=get_current_weather>{"city": "New York City", "state": "NY", "unit": "fahrenheit"}</function>, which is essentially the correct result, but with functionrbct instead of function.

With greedy sampling (temperature = 0, cf. #8132), the test passes. The test was not changed by #7294 and #8132, which changed the default sampling strategy not to be greedy, and at the time of #7294 did not set the enable_mixed_sampler option. Thus, this PR merely restores the original behavior of the test (pre #7294).

Test Coverage

PR fixes existing test.

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Summary by CodeRabbit

• Tests
  • Updated test configuration parameters to improve test reliability and consistency.

[ixlmar]

/bot run --stage-list "A10-PyTorch-2"

[tensorrt-cicd]

PR_Github #24621 [ run ] triggered by Bot. Commit: f385914

[ixlmar]

/bot run

[tensorrt-cicd]

PR_Github #24622 [ run ] triggered by Bot. Commit: f385914

[tensorrt-cicd]

PR_Github #24621 [ run ] completed with state ABORTED. Commit: f385914
LLM/main/L0_MergeRequest_PR #18586 (Blue Ocean) completed with status: ABORTED

[tensorrt-cicd]

PR_Github #24622 [ run ] completed with state FAILURE. Commit: f385914
/LLM/main/L0_MergeRequest_PR pipeline #18587 completed with status: 'FAILURE'

[ixlmar]

/bot run

[tensorrt-cicd]

PR_Github #24751 [ run ] triggered by Bot. Commit: 8a26eb7

[tensorrt-cicd]

PR_Github #24751 [ run ] completed with state FAILURE. Commit: 8a26eb7

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a temperature=0.0 parameter to two chat.completions.create calls within the test_structural_tag test function to ensure deterministic model output during testing, without introducing logic or control flow changes.

Changes

Cohort / File(s)	Summary
Test parameter addition tests/unittest/llmapi/apps/_test_openai_chat_guided_decoding.py	Added temperature=0.0 parameter to two calls to chat.completions.create within test_structural_tag to make model output deterministic

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: restoring greedy sampling in a test file, directly relating to the PR's core objective of fixing a failing CI test.
Description check	✅ Passed	The description comprehensively explains the issue (FlashInfer.sampling causing CI failure), the root cause (non-greedy sampling change), the solution (restoring greedy sampling), and references relevant prior PRs. It includes test coverage and checklist confirmation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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---

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📥 Commits

Reviewing files that changed from the base of the PR and between 24f5cd7 and 8a26eb7.

📒 Files selected for processing (1)

• tests/unittest/llmapi/apps/_test_openai_chat_guided_decoding.py (1 hunks)

🔇 Additional comments (2)

tests/unittest/llmapi/apps/_test_openai_chat_guided_decoding.py (2)

285-424: Inconsistency between AI summary and actual code.

The AI-generated summary states that temperature=0.0 is added to "two calls to chat.completions.create within test_structural_tag," but the code shows only one such call (lines 374-409). This discrepancy should be noted.

---

374-409: LGTM: Greedy sampling correctly restores test determinism.

Adding temperature=0.0 ensures deterministic output, which is essential for this test that validates exact structural tag formatting. This addresses the CI failure where non-greedy sampling produced malformed tokens like functionrbct instead of function.

---

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[ixlmar]

/bot run

[tensorrt-cicd]

PR_Github #24760 [ run ] triggered by Bot. Commit: 8a26eb7

[tensorrt-cicd]

PR_Github #24760 [ run ] completed with state SUCCESS. Commit: 8a26eb7
/LLM/main/L0_MergeRequest_PR pipeline #18677 completed with status: 'FAILURE'

[ixlmar]

/bot run

[tensorrt-cicd]

PR_Github #24881 [ run ] triggered by Bot. Commit: 8a26eb7

[ixlmar]

/bot run

[tensorrt-cicd]

PR_Github #24881 [ run ] completed with state SUCCESS. Commit: 8a26eb7
/LLM/main/L0_MergeRequest_PR pipeline #18784 completed with status: 'FAILURE'

[tensorrt-cicd]

PR_Github #24920 [ run ] triggered by Bot. Commit: 728bad8

[tensorrt-cicd]

PR_Github #24920 [ run ] completed with state SUCCESS. Commit: 728bad8
/LLM/main/L0_MergeRequest_PR pipeline #18820 completed with status: 'SUCCESS'