Hw Test Dedup

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

Steps the agent follows

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

1. Resolve inputs. Expand the file list (or discover files under the dir). Confirm the cluster grouping with the user when in <dir> mode.
2. 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.
3. 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.
4. 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.
5. 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).
6. 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.
7. 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.
8. Merge-plan. Per the Merge-planner persona, list the unique assertions to port into each survivor first; portability check.
9. 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