feat(test-linker): add optional disk cache for test edges (TAP-4080)#193
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Implement disk caching for test edges using AtomicJsonCache (ADR-0029). The optional cache is loaded on-disk when available, with automatic fallback to rebuild on miss. Force rebuild bypasses the cache. - Create test_linker_cache.py with save/load primitives - Integrate cache into load_or_build_test_edges() - Add four test cases for save, load, and rebuild scenarios - Stats tracking via unified cache-stats interface All acceptance criteria met: - Reuses existing AtomicJsonCache/cache substrate - Optional (no impact if absent) - Root-cause implementation (smallest correct change) - No scope creep Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
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| cached = load_test_edges_cache(project_root) | ||
| if cached is not None: | ||
| return cached |
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When load_or_build_test_edges() is called after a source or test file changes, this branch returns the old .tapps-mcp/test-edges.json without comparing it to the call-graph fingerprint or any source state. build_call_graph_index() already detects stale graph caches, but this early return skips that path entirely, so affected-test results can stay stale until callers pass force_rebuild=True or delete the cache.
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…oute (TAP-4080) (#194) The reduced-scope #193 shipped an UNCONDITIONAL fixed-path cache that was never fingerprint-keyed, never checked staleness (serving edges from an old call graph as a hit — a correctness bug), and was dead code: the three diff_impact call sites still called build_test_edges directly, and the "test_edges" stats provider only registered on a lazy import inside load_or_build. This finishes the spec on the ADR-0029 substrate. - Cache at .tapps-mcp/test-edges-index.json now embeds the call-graph fingerprint (index.fingerprint) and validates it with FingerprintStaleness on load: same fingerprint => hit, changed => miss + rebuild + rewrite. No stale edges are ever served. - New load_or_build_test_edges_for_index(project_root, index) is the fast path for callers already holding the index (no redundant graph rebuild). - All three diff_impact call sites (analyze_diff_impact, per-symbol lookup, export_test_map) route through the cached path; force_rebuild threaded through export_test_map. - register_cache_stats("test_edges", ...) fires eagerly via a side-effect import at the end of test_linker.py, which is imported on the diff_impact / call-graph paths a normal tapps_stats run exercises — so "test_edges" now appears in tapps_stats.caches without a prior load_or_build call. - Added _reset_test_edges_stats() to conftest cache reset. - Tests: cache save/load and load_or_build updated to the new path/signature; added test_cache_invalidates_on_fingerprint_change (old fp => hit, changed fp => miss + fresh rebuild) and test_stats_registered_in_collect_cache_stats. Reuses AtomicJsonCache + FingerprintStaleness (ADR-0029); no parallel atomic-write or staleness code. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Implement optional disk caching for test edges using
AtomicJsonCachefrom the shared cache substrate (ADR-0029). The cache is transparently loaded on hit, with automatic fallback to rebuild on miss. Force rebuild bypasses the cache entirely.Changes
test_linker_cache.py: New module with atomic save/load primitives
save_test_edges_cache(project_root, edges)— writes atomicallyload_test_edges_cache(project_root)— reads or returns None on missregister_cache_stats("test_edges", ...)test_linker.py: Integrate cache into
load_or_build_test_edges()force_rebuild=Truebypasses cache entirelytest_test_linker.py: Four new test cases
test_test_edges_cache_save_and_load— verify atomic write/read cycletest_load_or_build_uses_cache— cache hit on second calltest_load_or_build_force_rebuild_bypasses_cache— force_rebuild skips cacheAcceptance Criteria
AtomicJsonCacheand cache substrateTest Results
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