[MyPy] Fix mypy errors in easy tests/v1/kv_connector files (kv-A)

[nien-hui]

Co-Authored-By: Claude Fable 5.1

Purpose

PR kv-A of #49569: fix the mypy errors in the 19 "easy" files under tests/v1/kv_connector/

Preparatory PR per the plan: tests/v1/kv_connector stays in SEPARATE_GROUPS; kv-C moves it to SILENT_GROUPS once kv-B (claimed by @ntu-b12505041) is done.

Not a duplicate: #51043 and #55485 do not touch this directory, and no open PR here addresses mypy errors.

Fixes follow the same priority as PRs 1–4: assert x is not None narrowing, then precise annotations, then cast(), and scoped # type: ignore[code] only for intentional test stubs. A few test literals were corrected to the real types (e.g. set instead of list, bytes block hashes). Counts have drifted since the plan was written (test_lmcache_connector.py is 27 today vs 3 in the table); all 19 files are fixed to zero.

One kv-B file is touched: unit/utils.py gets TestExampleConnector.__test__ = False (one line), because the class is now imported into a test module for an isinstance narrow and pytest would otherwise try to collect it. Its own 6 mypy errors are kv-B scope and left as is.

Test Plan

FILES=$(git diff --name-only main...HEAD)
KV_A=$(echo "$FILES" | grep -v 'unit/utils.py')   # utils.py's remaining errors are kv-B scope

# silent mode, the strictness kv-C will enforce
for v in 3.10 3.12; do
  .venv/bin/mypy --python-version $v --follow-imports silent --warn-unused-ignores $KV_A
done

# hooks as CI runs them
pre-commit run mypy-3.10 --files $FILES
pre-commit run mypy-3.12 --hook-stage manual --files $FILES
pre-commit run ruff-check --files $FILES
pre-commit run ruff-format --files $FILES
pre-commit run typos --files $FILES

.venv/bin/python -m pytest -q $(echo "$FILES" | grep '^tests/v1/kv_connector/unit/test_')

Test Result

• mypy 1.20.2, --follow-imports silent, 3.10 and 3.12: the 19 kv-A files go from 63 errors to 0, no unused ignores. The rest of tests/v1/kv_connector still has errors in kv-B/kv-C files, as planned.
• pre-commit mypy-3.10, mypy-3.12, ruff-check, ruff-format, typos: pass.
• pytest on the 18 touched unit files: 151 passed, 6 skipped (hf3fs_fuse.io not installed). test_spec_decode_acceptance.py needs the PD server harness and was not run; its prompt loading was checked to give identical output with the new tokenizer.

AI assistance: prepared with Claude Code (Claude Fable 5.1); I reviewed every changed line and ran the commands above locally.

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

[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.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Team

Run ID: 538dde8d-89d0-4f90-ade7-39b5605b490d

📥 Commits

Reviewing files that changed from the base of the PR and between 144e79c and 637ddde.

📒 Files selected for processing (20)

• tests/v1/kv_connector/nixl_integration/test_spec_decode_acceptance.py
• tests/v1/kv_connector/unit/test_cache_pollution_prevention.py
• tests/v1/kv_connector/unit/test_error_propagation.py
• tests/v1/kv_connector/unit/test_flexkv_connector.py
• tests/v1/kv_connector/unit/test_handshake_pp_aggregation.py
• tests/v1/kv_connector/unit/test_hf3fs_client.py
• tests/v1/kv_connector/unit/test_invalid_blocks_correctness.py
• tests/v1/kv_connector/unit/test_kv_connector_lifecycle.py
• tests/v1/kv_connector/unit/test_kv_load_failure_recovery.py
• tests/v1/kv_connector/unit/test_lmcache_connector.py
• tests/v1/kv_connector/unit/test_lmcache_integration.py
• tests/v1/kv_connector/unit/test_mooncake_stats.py
• tests/v1/kv_connector/unit/test_moriio_tp_ack.py
• tests/v1/kv_connector/unit/test_nixl_simple_cpu_offload.py
• tests/v1/kv_connector/unit/test_remote_decode_lifecycle.py
• tests/v1/kv_connector/unit/test_remote_prefill_lifecycle.py
• tests/v1/kv_connector/unit/test_scheduler_kv_connector_override.py
• tests/v1/kv_connector/unit/test_tp_mapping.py
• tests/v1/kv_connector/unit/test_transfer_topology_sharded.py
• tests/v1/kv_connector/unit/utils.py

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📝 Summary

Summary by CodeRabbit

• Tests
  • Improved KV connector test coverage for configuration validation, lifecycle behavior, cache handling, failure recovery, and connector selection.
  • Updated test expectations for current data formats, request identifiers, tokenizer usage, and transfer metadata.
  • Added assertions to catch missing parameters, invalid states, and unexpected connector behavior earlier.
  • Refined test typing and fixtures to improve static validation and reliability.

Walkthrough

Changes

The pull request updates KV connector tests for revised tokenizer APIs, typed configuration, connector selection, KV event data shapes, lifecycle contracts, and static type-checking requirements.

KV connector test maintenance

Layer / File(s)	Summary
Tokenizer API migration tests/v1/kv_connector/nixl_integration/test_spec_decode_acceptance.py	The acceptance test uses get_tokenizer and casts the prompt list to list[str].
Connector configuration and selection assertions tests/v1/kv_connector/unit/test_cache_pollution_prevention.py, tests/v1/kv_connector/unit/test_error_propagation.py, tests/v1/kv_connector/unit/test_flexkv_connector.py, tests/v1/kv_connector/unit/test_invalid_blocks_correctness.py, tests/v1/kv_connector/unit/test_kv_connector_lifecycle.py, tests/v1/kv_connector/unit/test_nixl_simple_cpu_offload.py, tests/v1/kv_connector/unit/utils.py	Tests validate KV transfer configuration, KV role typing, connector instances, CPU offload setup, and pytest collection metadata.
KV event and transfer data shapes tests/v1/kv_connector/unit/test_lmcache_connector.py, tests/v1/kv_connector/unit/test_mooncake_stats.py, tests/v1/kv_connector/unit/test_moriio_tp_ack.py	Tests use byte-based hashes, grouped block identifiers, explicit non-null checks, and structured receive-transfer state.
Lifecycle and scheduler contract updates tests/v1/kv_connector/unit/test_kv_load_failure_recovery.py, tests/v1/kv_connector/unit/test_lmcache_integration.py, tests/v1/kv_connector/unit/test_remote_decode_lifecycle.py, tests/v1/kv_connector/unit/test_remote_prefill_lifecycle.py, tests/v1/kv_connector/unit/test_scheduler_kv_connector_override.py, tests/v1/kv_connector/unit/test_invalid_blocks_correctness.py	Tests validate prompt and transfer parameters, use current request identifiers and collection types, and align the scheduler mock signature.
Static typing and test fixture alignment tests/v1/kv_connector/unit/test_handshake_pp_aggregation.py, tests/v1/kv_connector/unit/test_hf3fs_client.py, tests/v1/kv_connector/unit/test_tp_mapping.py, tests/v1/kv_connector/unit/test_transfer_topology_sharded.py	Test doubles and constructor calls add targeted type-checker suppressions without changing runtime behavior.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 637dd

This updates KV connector test fixtures, type narrowing, and tokenizer usage to match current contracts without changing production behavior. No actionable merge-readiness risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 62.79% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 43 functions across 20 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the main change: fixing MyPy errors in the specified KV connector test files.
Description check	✅ Passed	The description directly explains the MyPy fixes, scope, deferred work, test plan, and test results for the changed files.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

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