[Misc] Add 20 regression tests for 11 tool parser bug fixes

[bbrowning]

Purpose

Claude Code and I audited recent tool parser bug-fix PRs (Sept 2025 until now) and found that several landed without corresponding test coverage. This is purely additive test coverage to prevent regressions as we refactor, cleanup, and redesign some of these areas.

• Mistral: fast detokenization text detection (PR Fix some Mistral parser issues #37209)
• Qwen3Coder: malformed XML crash, anyOf double-encoding, speculative decode streaming (PRs [Bugfix] fix Qwen3.5 tool calling bug #36774, qwen3coder tool parser fix anyOf double encoded parameters #36032, [Tool Parser] Fix Qwen3Coder streaming parameter loss with speculative decode #35615)
• DeepSeekV32: delimiter preservation with fast detokenization, skip_special_tokens adjustment (PR [Bugfix] Fix the issue where tool calling does not work when using fast detokenization with dsv32 #33964)
• GLM-4 MoE: zero-argument tool calls, transformers 5.x delimiter handling, Unicode character preservation (PRs fix: avoid crash on zero-arg tool calls in glm4 parser #32321, Fix GLM-4.6v flash tool calling in transformers 5.x #31622, [Bugfix] Fix Unicode issues in GLM-4 tool calling #30920)
• MiniMax M2: anyOf nullable parameter handling for non-null and null values (PR Fix optional parameter parsing in MiniMax M2 tool parser #32278 #32342)
• Step3p5: MTP-style variable-chunk and multi-token streaming (PR [Bugfix] Fix step3p5 parser when using mtp #33690)
• Kimi K2: native tool call ID extraction and multi-turn ID continuity (PR fix: preserve native tool call ID in multi-turn tool calling #32768)

Test Plan

pytest -sv tests/tool_parsers

Test Result

All the new tests passed, and all the old ones continue to pass.

510 passed, 1 skipped, 42 xfailed, 2 warnings

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[gemini-code-assist]

Code Review

This pull request introduces a comprehensive suite of regression tests across multiple tool parsers, including DeepSeekV32, GLM4-MoE, KimiK2, MinimaxM2, Mistral, Qwen3, and Step3p5. These tests address various edge cases and potential issues such as delimiter preservation, skip_special_tokens logic, handling of zero-argument and malformed tool calls, Unicode character preservation, native tool call ID extraction, anyOf nullable parameter parsing, fast detokenization, and streaming behavior with multi-parameter and variable-sized chunks. A review comment highlights a malformed JSON string in a MinimaxM2 test, which needs to be corrected to ensure the test functions as intended.

[bbrowning]

Gemini got confused counting JSON braces within the xml tags within the Python strings of the test, but I double-checked the test it highlighted just to be sure. And then gave it a thumbs-down for good measure, in case they use that to improve training.

[sfeng33]

LGTM, thank you for the thorough work!