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[Test][Tool Parser] Add streaming split-invariance test to the common suite - #55079
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… suite A streaming tool parser is a state machine over an arbitrary partition of its token stream, so its result must not depend on how many tokens the server happens to put in each delta. The common suite only ever streams one token per delta, which is a single partition, so a tag that is mishandled only when it straddles one particular delta boundary is never exercised. Issue vllm-project#48342 names this gap directly: "The existing tests stream strictly one token per delta, so this multi-token-delta path is untested." The same class has now been filed parser by parser: vllm-project#48020 and vllm-project#48342 (deepseek_v3), vllm-project#47907 (granite, granite-20b-fc, gigachat3), vllm-project#48294 (llama3_json, jamba, ernie45) and vllm-project#48347 (internlm). This adds the property test that covers the class once, for every parser using the common suite, instead of one issue per parser. test_streaming_split_invariance replays each sample as every two-delta split (exhaustive, n-1 of them) plus 100 seeded random batchings of 1-4 tokens, and compares each against the one-token-per-delta baseline. The baseline is the streamed result rather than the non-streamed parse, so the check stays meaningful for parsers whose non-streaming path is separately known to be broken. Failures report the shortest failing batching, so the repro names the exact boundary. run_tool_extraction_streaming recovers token ids by re-tokenizing each delta, which does not round-trip once a delta holds several tokens and would feed parsers ids the model never generated. The new batched streamer carries the real ids through instead. Currently failing parsers are marked xfail(strict) against the issues above, so this lands green and flips to a failure when each fix merges. Test: .venv/bin/python -m pytest tests/tool_parsers tests/parser -q 969 passed, 39 xfailed in tests/tool_parsers (15 pre-existing errors from the gated meta-llama repo, present without this change) 4316 passed in tests/parser AI assistance was used to write this change. Co-authored-by: Claude Opus 5 <noreply@anthropic.com> Signed-off-by: David Wu <133224895+David-Wu1119@users.noreply.github.com>
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| reconstructor.append_delta(delta_message) | ||
| previous_text = current_text | ||
| previous_tokens = current_tokens | ||
| return reconstructor |
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When the final batch is the one that first lets a parser emit the function name, this helper returns immediately without exercising the serving layer's end-of-generation flush. Production calls DelegatingParser.finalize_generation, which appends get_remaining_unstreamed_args() to the last tool delta; parsers such as Step3 can return the name before emitting their buffered arguments. The test can therefore report empty or truncated arguments solely because of the harness and keep a parser marked xfail even when client-visible output is split-invariant. Run the batching through Parser.parse_delta(..., finished=True) or reproduce the same final flush before returning.
AGENTS.md reference: AGENTS.md:L90-L92
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Addressed in b61c88f. After the last delta, the batched replay now appends tool_parser.get_remaining_unstreamed_args() to the last reconstructed tool call, the same tail _append_unstreamed_tool_args adds in finalize_generation. The one-token-per-delta baseline gets the same flush, so both sides of the comparison are client-visible output.
One deliberate difference: the harness applies the tail whenever a tool call was reconstructed, while finalize_generation only appends it when the final delta itself carries a tool call. So the harness can miss a tail that production drops, but it cannot report a loss that production would recover.
This was a real overstatement for one parser. Re-measuring the description's table with the flush, granite-20b-fc's single call differs from the baseline on 5 of 24 two-delta splits, not 24 of 24. The other 19 were missing only argument text that the flush restores; the 5 that remain ([1, 24] through [5, 20]) drop the call entirely. The other rows are unchanged, and I've corrected the description.
No xfail is rescued. step3 still ends at "{}" after the flush (it stores parsed arguments under "parameters", and the base get_remaining_unstreamed_args reads "arguments"), and deepseek_v3 still ends at "". The markers are strict=True, so a rescued parser would XPASS and fail; pytest tests/tool_parsers -k split_invariance gives 4 passed, 10 xfailed.
| batchings = two_chunk_groupings(len(token_texts)) + random_groupings( | ||
| len(token_texts), | ||
| count=RANDOM_GROUPING_COUNT, | ||
| seed=RANDOM_GROUPING_SEED, | ||
| ) |
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For outputs longer than four tokens, these generators never produce [len(token_texts)]: two_chunk_groupings always creates exactly two deltas, while the random generator caps every chunk at four tokens. A short response may be delivered entirely in one scheduler update, and several parser failures are specifically triggered when the whole tool call lands in one delta, so such a regression can still pass this purported arbitrary-partition test. Add the single-chunk grouping explicitly.
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Agreed, fixed in b61c88f. The whole stream in one delta, [len(token_texts)], is now always the first batching tried, ahead of the two-delta splits and the random groupings. Several of the linked issues trigger on exactly that case.
| if failures: | ||
| lengths, err = min(failures, key=lambda item: len(item[0])) | ||
| raise AssertionError( |
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For every parser currently marked xfail whose single-call batching fails, this raise occurs during the first loop iteration, so pytest records the expected failure and never exercises any parallel-call batching. That leaves the advertised parallel split coverage absent for all known-broken parsers and can hide independent parallel-call regressions until the single-call issue is fixed. Parameterize the single and parallel outputs as separate test cases rather than combining both behaviors under one early failure and one xfail marker.
AGENTS.md reference: AGENTS.md:L93-L94
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Fixed in b61c88f. test_streaming_split_invariance is now parametrized over single and parallel, so each case gets its own result and a single-call failure no longer stops the parallel batchings from running. An xfail_streaming entry under the plain test name still covers both cases, and a test_streaming_split_invariance[parallel] (or [single]) key overrides one of them.
Under strict xfail, every parser currently marked also fails its parallel case, so no markers changed: 4 passed, 10 xfailed across the 7 parsers that use the common suite.
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…lta case, split single/parallel
Three points from the automated review, all fair:
The batched replay stopped at the last delta and never applied the
end-of-generation flush the serving layer performs, where whatever the
parser parsed but did not stream is appended to the last tool call. A
parser that sends its name before its buffered arguments depends on that
flush, so the harness could have reported argument loss the client never
sees. It now mirrors the flush via get_remaining_unstreamed_args(). Checked
against the two parsers this most affects: after the flush step3 still
yields "{}" (it stores parsed arguments under "parameters", the flush reads
"arguments") and deepseek_v3 still yields "", so every existing xfail stands
and none was a harness artifact.
Neither grouping generator produced the whole-stream-in-one-delta partition
for streams longer than the random chunk cap, and that is precisely the case
several of the linked issues trigger on. It is now included explicitly.
Single and parallel outputs shared one loop with one early raise, so a
parser marked xfail on its single call never had its parallel batching
exercised. They are separate parametrized cases now; xfail entries keyed by
the plain test name apply to both, and a label-specific key can override.
Under strict xfail every currently-failing parser also fails the parallel
case, so no marker changed.
Test: .venv/bin/python -m pytest tests/tool_parsers -q
(cohere excluded: needs the cohere_melody package)
split-invariance cases: 4 passed, 10 xfailed
ruff check and ruff format --check clean on both files
AI assistance was used to write this change.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Signed-off-by: David Wu <133224895+David-Wu1119@users.noreply.github.com>
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@bbrowning @chaunceyjiang could one of you add the ready label or run /ci run when you have a moment? Review comments are addressed. |
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Could a maintainer kick off CI on this? pre-run-check fails only because I have fewer than 4 merged PRs in this repo, so no CI has run yet. The change is tests-only (+264/−3, 7 files): it adds test_streaming_split_invariance to the shared ToolParserTests mixin, plus the batching helpers it needs. #48342 names exactly this gap ("the existing tests stream strictly one token per delta, so this multi-token-delta path is untested") as why the bug class keeps coming back. Locally, tests/tool_parsers tests/parser gives 5083 passed, 1 skipped, 44 xfailed. The 15 errors in test_llama3_json_tool_parser.py are pre-existing 401s from the gated meta-llama repo and reproduce on clean main. |
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This pull request has merge conflicts that must be resolved before it can be |
Resolve the conflict in tests/tool_parsers/test_granite_tool_parser.py by taking upstream's version: vllm-project#49648 migrated Granite to the streaming Parser Engine and removed its xfail block, and test_streaming_split_invariance now passes for granite without an xfail. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: David-Wu1119 <133224895+David-Wu1119@users.noreply.github.com>
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Merged current Re-run on the merged tree: |
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@chaunceyjiang @bbrowning could one of you add the |
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This pull request has merge conflicts that must be resolved before it can be |
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Closing, since this hasn't been picked up and now conflicts with main. The split-invariance problem it tests for is still described in #55082. |
Purpose
A streaming tool parser is a state machine over an arbitrary partition of its
token stream. Which tokens land in which delta is decided by the scheduler,
--stream-interval, and speculative decoding, so the parsed result must notdepend on it. The common suite streams one token per delta, which is a
single partition, so a tag mishandled only when it straddles one particular
delta boundary is never exercised.
Issue #48342 names this gap directly:
The same failure class has since been filed parser by parser:
That is five issues and nine parsers for one property. This PR adds the
property test so the class is covered once, for every parser using the common
suite, rather than one issue per parser.
What it does
ToolParserTests.test_streaming_split_invariancereplays each config'ssingle and parallel tool-call outputs (as separate parametrized cases) as:
n-1of them), andand compares each against the one-token-per-delta baseline.
Two deliberate choices:
parsers have separately known non-streaming bugs (see
xfail_nonstreaming),and using them as the oracle would report those instead of the property
under test.
exact boundary rather than a random 30-chunk split.
run_tool_extraction_streamingrecovers token ids by re-tokenizing eachdelta. That does not round-trip once a delta holds several tokens (
"<|a|>"as one string does not tokenize like its pieces), so a batched replay would
feed parsers ids the model never generated.
run_tool_extraction_streaming_batchedcarries the real ids through the batching instead, and after the last delta
appends
get_remaining_unstreamed_args()to the last tool call, asfinalize_generationdoes in the serving layer, so only client-visible losscounts. Existing behaviour is untouched.
Result
Parsers currently failing the property are marked
xfail(strict=True)againstthe issues above, so this lands green and flips to a failure the moment each
fix merges.
<<step3 is the one row with no issue filed; the others match the table above.
Counts include the end-of-stream flush. Without it granite-20b-fc differed on
24/24 splits, but 19 of those were missing only argument text the serving layer
restores (see the review thread); every other row is the same either way.
Not a duplicate
Checked per AGENTS.md. The open PRs listed above are bugfixes to individual
parsers; this is the missing test coverage whose absence #48342 identifies
as the reason the class kept recurring. It deliberately does not change any
parser, so it does not collide with #48636, #48343, #48295, #50461 or #49648.
When those merge, their
xfailentries are removed in the same PR.Test plan
.venv/bin/python -m pytest tests/tool_parsers tests/parser -q \ --ignore=tests/tool_parsers/test_cohere_command_tool_parser.pytests/tool_parsers+tests/parser: 5083 passed, 1 skipped, 44 xfailedtests/tool_parsers/test_cohere_command_tool_parser.pywas excluded: itneeds the
cohere_melodypackage, which is not installed here.tests/tool_parsers/test_llama3_json_tool_parser.pyarepre-existing on this machine (gated
meta-llama/Llama-3.2-1B-Instruct,HTTP 401) and reproduce without this change.
ruff checkandruff format --checkclean.The findings above were also reproduced with a standalone script that calls
only
extract_tool_calls_streaming, with no test helpers, to rule out theharness as the cause.
No model evaluation: tests only, no serving or output path is modified.
AI assistance was used to write this change.
cc @bbrowning @chaunceyjiang, who own
tests/parser/engineand the streamingparser engine work this sits next to. Happy to split the
xfailmarkers into afollow-up, or to narrow the sampled batchings, if either would make review easier.