Files

Gahow Wang c5f552e122 test(policy): Theorem 1 no-starvation property tests

Adds the algorithm-layer guarantee tests for
docs/KVC_ROUTER_ALGORITHM.md §4.1. The full Dispatch loop
lives in replay.py (HTTP + mooncake), but the policy-layer
guarantee is testable in isolation: under any reject
sequence, select() must keep returning a valid worker.

Cases:
  - select returns a valid decision even after every (s,d)
    is past τ_reject (degenerate fallback)
  - |D|·τ_reject rejects suffice to explore every D
    (cannot trap a session on one D under universal
    rejection)
  - degenerate fallback picks the least-rejected D
    (Algorithm 1 line 4)
  - per-(session, D) isolation: session A's blacklist
    does not affect session B
  - migration_reject_threshold=0 disables blacklist
  - select() does NOT silently bump the reject counter
    (the only mutator is record_admission_reject)

Adds tests/_fixtures.py with minimal make_topology() and
make_request() helpers that skip build_single_node_topology's
GPU-budget validation (irrelevant in unit tests).

Verified locally: 20/20 passing under pytest 9.0.3. The
six new tests cover only Algorithm 1's policy-layer
half of Theorem 1; the reset-on-success half lives in
Algorithm 3 (replay.py) and is a future test target.

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__init__.py

test(policy): unit tests for Algorithm 1 lex scoring

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_fixtures.py

test(policy): Theorem 1 no-starvation property tests

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README.md

test(policy): unit tests for Algorithm 1 lex scoring

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test_no_starvation.py

test(policy): Theorem 1 no-starvation property tests

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test_policy_scoring.py

test(policy): unit tests for Algorithm 1 lex scoring

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README.md

Tests

Pure-Python unit + property tests for the algorithm layer. These tests do not import SGLang and do not need a GPU — they validate the routing algorithm (Algorithm 1/2/3 in docs/KVC_ROUTER_ALGORITHM.md) and its theorems against the pure functions extracted from policies.py.

Run

uv sync --group test
uv run pytest

Or, without uv:

pip install pytest
PYTHONPATH=src pytest tests

Scope

test_policy_scoring.py — Algorithm 1 lex-score properties (overlap dominates sticky, load-floor gating, tie-breakers).
test_no_starvation.py — Theorem 1: bounded retries before some D either accepts or the least-rejected D is forced through the degenerate path.

Future:

block-level eviction MockRadixCache tests (see docs/BLOCK_LEVEL_EVICTION_DESIGN_ZH.md §5).
D→P sync staleness_budget property tests (see docs/D_TO_P_SYNC_CONTRACT_ZH.md §1).

Why no integration tests here

Anything that needs SGLang, mooncake, or a real model is an integration test and must run on hardware. Those tests live as scripts/sweep_*.sh under the evaluation protocol in docs/EVALUATION_PROTOCOL_ZH.md.