test: mutation-harden gas/index unit coverage

[thedavidmeister]

Summary

Mutation-hardens the GasManager unit suite (src/gas/index.ts). A
scoped adversarial-mutation pass over the gas-estimation peripheral logic
found 10 surviving mutants in the existing src/gas/index.test.ts suite —
all in the constructor default-value logic, the onTransactionMine
threshold/deadline arithmetic, and the watchGasPrice idempotency guard.

This PR adds 6 discriminating tests (tests-only; no src/ change) that
each pass on the clean baseline and fail under the corresponding mutation.
Every previously-surviving mutant is now killed.

Mutation matrix

#	Source line	Mutation	Before	After
M1	maxGasPriceMultiplier = baseGasPriceMultiplier + 50	+ 50 → - 50	SURVIVED	KILLED
M2	if (config.txTimeThreshold !== undefined)	guard → false	SURVIVED	KILLED
M3	if (config.gasIncreasePointsPerStep !== undefined)	guard → false	SURVIVED	KILLED
M4	if (config.gasIncreaseStepTime !== undefined)	guard → false	SURVIVED	KILLED
M13	gasIncreasePointsPerStep: number = 3	3 → 7	SURVIVED	KILLED
M14	txTimeThreshold: number = 30_000	30_000 → 1	SURVIVED	KILLED
M15	gasIncreaseStepTime: number = 60 * 60 * 1000	→ 1	SURVIVED	KILLED
M5	if (txMineRecord.length >= this.txTimeThreshold)	>= → >	SURVIVED	KILLED
M6	this.deadline = Date.now() + this.gasIncreaseStepTime	+ → -	SURVIVED	KILLED
M9	if (this.isWatchingGasPrice) return;	guard → false	SURVIVED	KILLED

Already-covered (audited, no new test)

• Math.min(max, multiplier + step) clamp → Math.max — KILLED by existing
  "should not increase the multiplier over the max value".
• >= → <= on the deadline-reset comparison — KILLED by existing
  "under threshold and reset" (past deadline).
• isOk() branches in init/watchGasPrice — covered by existing
  init/interval tests.

Equivalent (intentionally not tested)

• if (this.deadline && Date.now() >= this.deadline) — dropping the
  this.deadline && short-circuit is equivalent in practice: deadline is
  only ever undefined or a positive timestamp, and Date.now() >= undefined
  is already false, so no reachable state distinguishes the mutant.
• >= vs > on the deadline comparison would only be discriminated by
  Date.now() === deadline exactly, which is non-deterministic.

New tests added (src/gas/index.test.ts, +94 lines)

• should not start a second watcher when already watching (M9)
• should apply class defaults when optional config fields are omitted (M1/M2/M3/M4/M13/M14/M15)
• should use provided optional config values over the defaults (assignment branches)
• should increase the multiplier when mine time equals the threshold exactly (M5)
• should set the deadline to now plus the step time when increasing (M6)
• should not reset the multiplier when the deadline is still in the future (future-deadline guard)

Gaps checklist

• Constructor optional-field default branches
• Class-field default values (points / step time / threshold)
• maxGasPriceMultiplier = base + 50 fallback
• onTransactionMine >= threshold boundary
• Deadline + stepTime arithmetic
• Future-deadline no-reset path
• watchGasPrice double-start idempotency
• init/watchGasPrice isErr branches — already covered by existing tests (audited)

Verification

• tsc -p ./tsconfig.check.json clean
• eslint ./src/gas/index.test.ts clean
• Full vitest unit suite green: 847 tests passed (59 files + logger)
• git diff src/ is empty — tests-only change
• The e2e fork test jobs are a pre-existing environmental red (RPC/secrets) and are untouched by this PR.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Tests
  • Expanded coverage for gas pricing behavior, including repeated watch calls, stop watching, default configuration handling, and gas adjustment timing.
  • Added checks for edge cases around transaction mining, such as exact threshold timing and preserving pending adjustment windows.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 45acb8fd-4a44-4613-a21d-75e070652a54

📥 Commits

Reviewing files that changed from the base of the PR and between fc791fb and 27578b6.

📒 Files selected for processing (1)

• src/gas/index.test.ts

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Walkthrough

Adds 93 lines of new tests to src/gas/index.test.ts covering three areas: watchGasPrice idempotency (no duplicate intervals, unwatchGasPrice clears state), GasManager constructor defaults and overrides, and onTransactionMine edge cases (exact threshold, deadline arithmetic, no multiplier reset when deadline is future).

Changes

GasManager test coverage

Layer / File(s)	Summary
watchGasPrice, constructor defaults, and onTransactionMine tests src/gas/index.test.ts	Adds tests asserting a second watchGasPrice call reuses the existing handle; constructor applies defaults for omitted fields and respects provided overrides; onTransactionMine increases multiplier at exact threshold, sets deadline to Date.now() + gasIncreaseStepTime on increase, and skips multiplier reset when existing deadline is still future.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the test-only gas/index coverage hardening and is concise.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-06-15-solver-config-coverage

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