test-manual-mock-cleanup

manual mock cleanup in a lifecycle hook, which the Jest config already does

Deterministic checkadvisory by defaultbasetests

The argument

Mock Cleanup

Mock cleanup is handled by Jest config, not per-test code. Set these in the package's Jest config:

// jest.config.js / jest.config.ts
{
	clearMocks: true,    // clear call tracking (calls, instances, results) before each test
	restoreMocks: true,  // restore jest.spyOn originals before each test
}

With these set, every mock starts each test with clean call tracking and its setup() factory wires the return value fresh. Do not add manual mockClear() calls or a cleanup beforeEach — the config does it.

clearMocks: true — clears calls, instances, contexts, and results before each test (equivalent to jest.clearAllMocks()). It does not clear mockReturnValue / mockImplementation — that is resetMocks. Because every test re-sets its return values in setup(), clearMocks is sufficient and avoids wiping implementations; reach for resetMocks only if a package genuinely needs return values auto-cleared.
restoreMocks: true — additionally restores the original implementation of every jest.spyOn before each test (it does not affect standalone jest.fn() return values).

If the package's Jest config lacks these: do NOT add them. clearMocks changes behavior for every existing test in the package — any test relying on a mock set once at module scope or in beforeAll will break (live example: adding it to a real package broke 22 import-time-construction tests). A repo-wide behavior change is a human's decision, not a test task's side effect. Instead:

Build fresh jest.fn() mocks inside each setup() factory call (and construct a fresh subject per call), so call tracking cannot accumulate across tests without any config or hooks.
For module-level mocks that must persist (a jest.mock factory), reset them at the top of setup() (.mockReset() + re-wire), or assert only with toHaveBeenCalledWith — positive assertions are unaffected by accumulated calls; avoid not.toHaveBeenCalled on shared mocks.
Record the missing config as friction (area: "environment") so the repo owner can adopt it deliberately.

The proof

failsubject.unit.test.ts

import { expect, describe, test, jest, beforeEach } from '@jest/globals';

const mockGetTimezone = jest.fn<() => string>();

describe('subject', () => {
	beforeEach(() => {
		jest.clearAllMocks();
	});

	test('reads the timezone', () => {
		mockGetTimezone.mockReturnValue('UTC');

		expect(mockGetTimezone()).toBe('UTC');
	});
});

passsubject.unit.test.ts

import { expect, describe, test, jest } from '@jest/globals';

const mockGetCurrency = jest.fn<() => string>();

const setupCurrency = () => {
	mockGetCurrency.mockReset();
	mockGetCurrency.mockReturnValue('GBP');

	return { currency: 'GBP' };
};

describe('subject', () => {
	test('reads the currency', () => {
		const { currency } = setupCurrency();

		expect(mockGetCurrency()).toBe(currency);
	});
});

Turn it down

Both lines go in your lightsout.config.json.

"standards-checks": { "test-manual-mock-cleanup": "advisory" }

"standards-checks": { "test-manual-mock-cleanup": "off" }