docs: Test suite development summary (346→350 tests, 5-tier coverage)

[ranxianglei]

Summary

This issue documents the comprehensive test suite development for opencode-acp, covering the period from the initial ACP rebrand through the msgid expansion PR (#1).

Test Suite Growth

Phase	Tests	Files	Commit
Baseline (existing from DCP fork)	95	10	d5f1540
Tier 1: Pure function unit tests	+83	+6	04105e2
Tier 2: Mock-data unit tests	+68	+4	7471a1b
Functional: Compress pipeline tests	+77	+3	90b8c00
E2E: Full pipeline tests	+21	+2	7268202
Review fixes + backward compat	+4	0	17aa4c1, f0cf9d1
Total	350	22	—

New Test Files (12)

Tier 1 — Pure Function Tests (no dependencies, no mocks)

File	Tests	Source Module
config-validation.test.ts	~18	lib/config-validation.ts — extracted pure validation
priority-classify.test.ts	~15	lib/priority.ts — message classification
shape.test.ts	~12	lib/shape.ts — token estimation
query-pure.test.ts	~14	lib/query.ts — context query logic
gc-truncate-pure.test.ts	~12	lib/gc/truncate.ts — GC truncation params
state-utils-pure.test.ts	~12	lib/state/utils.ts — state utilities

Tier 2 — Mock-Data Tests

File	Tests	Source Module
query-mock.test.ts	33	lib/query.ts — with mock messages
gc-truncate-mock.test.ts	11	lib/gc/truncate.ts — with mock state
strategies-dedup.test.ts	12	lib/strategies/dedup.ts — dedup strategy
strategies-purge-errors.test.ts	12	lib/strategies/purge-errors.ts — error purging

Functional — Compress Pipeline

File	Tests	Source Module
compress-search.test.ts	22	lib/compress/search.ts — boundary resolution
compress-state.test.ts	21	lib/compress/state.ts — block allocation
message-ids.test.ts	34	lib/message-ids.ts — ID formatting/parsing/assignment

E2E — Full Pipeline

File	Tests	Coverage
e2e-message-transform.test.ts	11	Full hooks pipeline: filtering, hallucination stripping, compression blocks, pruning, manual trigger, persistence
e2e-blocks-nudges.test.ts	10	Nudge injection, block aging, session switch, tool part IDs, block consumption

Key Quality Improvements

Bug Fixes Found Through Testing

1. resetOnCompaction didn't clear messageIds (lib/state/utils.ts) — production bug caught by test review
2. purgeErrors.turns < 1 validation was lost during extraction — restored

Review-Driven Fixes

• Extracted lib/config-validation.ts from lib/config.ts — pure validation without jsonc-parser dependency, testable in isolation
• Fixed misleading test names, missing mock fields, trivial assertions
• Added backward compat migration for 4-digit→5-digit message refs (PR feat: expand message ref format from 4-digit to 5-digit (9999→99999) #1)

Backward Compatibility Tests

• parseBoundaryId normalizes 4-digit refs to 5-digit
• Old persisted state with m0001 keys migrates to m00001 on load
• Roundtrip stability: old format → parse → format → new format

Test Architecture

• Runner: node --import tsx --test tests/*.test.ts (Node built-in test runner)
• Pattern: node:test + node:assert/strict (no vitest/jest)
• Mocks: Manual factories (buildConfig(), buildMessages(), textPart(), toolPart())
• CI: GitHub Actions — typecheck + test + build (Node 22/24 matrix)

Documentation

• TESTING.md — 566 lines: running tests, framework, categories, coverage tables, writing guide
• AGENTS.md — Updated with mandatory dual-agent review for code + tests

[ranxianglei]

Good Job