hw-test-dedup

Testing & Quality

Find and remove redundant FBOSS agent_hw_tests without losing coverage. Use when asked to reduce/combine/dedup HW tests, retire non-dataplane (set/get) tests where dataplane tests exist, or cut HW test runtime while keeping coverage. Report-first; applying edits is a separate opt-in step.

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Source SKILL.md: https://github.com/facebook/fboss/blob/HEAD/fboss/agent/test/agent_hw_tests/.llms/skills/hw-test-dedup/SKILL.md

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HW Test De-duplication

Given a set of FBOSS agent_hw_tests, find test cases whose hardware coverage is fully contained in other tests, and recommend removing them — fewer tests, identical coverage. Default output is a report; turning recommendations into code edits is a separate, confirmation-gated step.

IMPORTANT: report-first, never auto-post

Default run produces a report only. It never edits tests or creates diffs unless --apply is passed AND the user confirms.
It never submits/publishes to Phabricator on its own.
When a removal cannot be proven safe, the test is kept and the reason is written down. Bias is always toward keeping coverage.

When to use

"dedup / combine / reduce these HW tests", "retire set/get tests where we have dataplane tests", "cut HW test count without losing coverage".
Scope: fbcode/fboss/agent/test/agent_hw_tests/ (this version). Other test trees are out of scope.

Invocation

Form	Meaning
`/hw-test-dedup <file1> <file2> ...`	Analyze an explicit set of test files.
`/hw-test-dedup <dir>`	Discover + cluster the test files under a dir, then analyze per cluster.
`--apply`	After analysis, apply the folds/removals as draft diffs (gated; see Apply rules).
`--deep-verify`	Opt-in empirical SAI call-trace check for top candidates (needs build/run).
`--self-test`	Run against the pinned eval corpus and diff verdicts vs `references/eval/`.
`--gap-report <D1,D2,...>`	Compare this skill's recommendations to already-landed reduction diffs; emit a gap report.
`--resume`	Continue from the last completed phase checkpoint.

Steps the agent follows

The orchestration is implemented in scripts/dedup-workflow.js (run via the Workflow tool). Follow these steps:

Resolve inputs. Expand the file list (or discover files under the dir). Confirm the cluster grouping with the user when in <dir> mode.
Pre-filter (deterministic, no LLM). Run scripts/prefilter.js to cluster by fixture base + feature area and prune pairs that obviously can't overlap. Pruned pairs are recorded for the report.
Profile each test (fingerprint). Per the Fingerprinter persona (references/personas.md) and references/fingerprint-schema.md, emit a coverage profile per test. Resolve helper code transitively. Pass the roster by file reference, not inlined.
Count-check completeness (deterministic). Run scripts/roster-count.js; the fingerprint count per file must equal the TEST_F/TEST_P/TYPED_TEST count. A mismatch hard-fails the file.
Detect overlaps + apply gates. Per the Subset-detector persona over pre-filtered pairs, under the 6 universal gates (references/universal-gates.md) plus the active coverage pack (references/coverage-packs/<area>.md).
Second opinions (adversarial). Per the Skeptic persona: 1 lens in report mode, 3 diverse lenses (unanimous-safe) in --apply mode. Refute-by-default; ≥1 reads raw source.
Reconcile (deterministic). Build the subset→superset graph; keep a maximal antichain; never remove a node whose only superset is itself removed; last-feature-owner is never removable.
Merge-plan. Per the Merge-planner persona, list the unique assertions to port into each survivor first; portability check.
Report (and, with --apply, perform merge → delete → arc f/arc lint → review pass → one commit per file → draft diffs).

Hard safety rules (enforced in code by the workflow)

A test that is the last owner of any ProductionFeature is never removable.
A removal requires the surviving test(s) to satisfy all universal gates (references/universal-gates.md).
--apply is allowed for an area only once that area has (a) a validated coverage pack, (b) its own eval corpus with a passing --self-test, and (c) a human spot-check of a pilot report. ACL is the first such validated area; every other area is report-only until it meets the bar.

Reference material

File	What
`references/personas.md`	The 6 agent personas + their output schemas.
`references/universal-gates.md`	The 6 universal safety gates.
`references/fingerprint-schema.md`	The per-test coverage-profile schema.
`references/warmboot-semantics.md`	`verifyAcrossWarmBoots` behavior across the 4 base classes.
`references/coverage-packs/*.md`	Per-area extra checks (acl validated; ecmp/mirror/trunk/srv6 drafted, report-only; qos/copp stubs).
`references/eval/`	Ground-truth corpora + how `--self-test` / `--gap-report` use them.
`references/contributing.md`	How to add a coverage pack / gate / eval corpus.
`references/design.md`	The design of record.