The original docs/testing.md mentioned finding existing tests as step 1
of the checklist but never explicitly said "if existing coverage
already addresses your case, extend it; don't duplicate." Adds a
prominent "First principle" section that names extend-vs-new as the
preferred outcome and lists three duplicated init_and_load blocks as
the most common form of test rot.
Adds an extra checklist item: verify your change makes an *existing*
test fail before it makes a new one pass — if you can break the code
without breaking a test, that coverage gap is the bug to fix first.
Strengthens the AGENTS.md callout so the principle ("always check what
already covers it") is in scope from the top of every session.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Maps the test surface (engine integration tests by area, CLI/server
tests, helpers harness, fixtures, failpoints feature, RustFS S3
integration, OpenAPI drift) and gives a before-every-task checklist:
find existing tests for the area, run them as a clean baseline, plan
the new test up front, reuse helpers, mind the layer boundary per
invariants §VII.33.
Notes that there's no coverage tooling today — coverage knowledge
comes from reading and running the relevant integration tests, not a
tarpaulin/codecov report.
Threaded into AGENTS.md as the third required-reading file alongside
invariants.md and lance.md, with a Claude-Code @-import so agents
load it on every turn.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
