Add direct unit coverage for Neo.util.Date

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Context

Every date surface in Neo computes its grid through one shared helper, Neo.util.Date: the calendar month, week and year views, Neo.form.field.Date, Neo.date.DayViewComponent, the calendar's event store and its drag plugins.

Measured on 2026-09-19 at dev@afddc57634: no file under test/playwright/ references src/util/Date.mjs — not by import, not by method name — while more than ten modules under src/ import it. Its eight static methods are exercised today only as a side effect of rendering a calendar.

The Problem

Week arithmetic is where off-by-one bugs live: leap years, a month that begins on a Sunday, a weekStartDay other than Monday, and the ISO rule that puts the first days of January in the last week of the previous year. Because nothing asserts these methods directly, such a bug first appears as a wrong calendar, and whoever fixes it has to reconstruct the failing case from a rendered component before they can even see it.

Direct coverage turns that into a one-line failure with the inputs printed.

The Architectural Reality

src/util/Date.mjs — class Neo.util.Date (the local binding is DateUtil), extends Neo.core.Base. Eight static methods, all pure, none touching the DOM or a worker:

The Fix

Add one new spec: test/playwright/unit/util/Date.spec.mjs.

Copy the shape from its sibling test/playwright/unit/util/String.spec.mjs — the first eleven lines matter and are not optional:

import {setup} from '../../setup.mjs';

setup({
    appConfig: {
        name: 'DateUtilTest'
    }
});

import {test, expect} from '@playwright/test';
import Neo            from '../../../../src/Neo.mjs';
import * as core      from '../../../../src/core/_export.mjs';
import DateUtil       from '../../../../src/util/Date.mjs';

test.describe('Neo.util.Date', () => {
    // your tests
});

setup() must be called before the other imports; that is how the Neo class system is initialised for the unit tier.

Cases worth asserting — pick the ones you can state confidently; you do not have to cover all eight methods to have a useful PR:

• clone() returns a different object with an equal value, and passes null through.
• getDaysInMonth() across February 2024 (29) and February 2023 (28).
• getFirstDayOfMonth() and getFirstDayOffset() for a month starting on a Sunday, with weekStartDay: 0 and with weekStartDay: 1 — the offset is documented as 0–6 and the wrap is the interesting half.
• getWeekOfYear() on the ISO boundary: 2021-01-01 (a Friday) and 2019-12-30 (a Monday) are the classic pair where the calendar year and the ISO week year disagree.
• matchDate() for two Date objects on the same day at different times.
• getWeeksOfMonth() is documented as returning 5 or 6. February of a non-leap year that begins exactly on weekStartDay is 28 days in exactly four rows. Assert what the function actually returns for that input and say so in your PR — if it is not 4, that is worth knowing, and it is a finding rather than something for you to fix here.

Deterministic inputs only: construct explicit new Date(2024, 1, 1) values. No new Date(), no "today" — a test that depends on the day it runs will fail for someone else.

How to run it

npm install
npx playwright test -c test/playwright/playwright.config.unit.mjs test/playwright/unit/util/Date.spec.mjs

The whole unit tier is npm run test-unit. Do not run a bare npx playwright test — this repository has several Playwright configurations and the default one is not the unit tier.

Acceptance Criteria

• test/playwright/unit/util/Date.spec.mjs exists and follows the setup()-first shape of its sibling specs.
• At least four of the eight methods are asserted, each with inputs written out literally — no dependency on the current date, the machine's locale, or test execution order.
• The spec passes on the unit configuration, and the PR body says how you ran it.
• The getWeeksOfMonth four-row case is either asserted or reported in the PR body with the value it returned.
• No file outside test/playwright/unit/util/ is changed. If a test of yours goes red against src/util/Date.mjs, do not fix the source here — say so in the PR and we will open a separate issue for the fix, with your test as its evidence.

Out of Scope

• Changing anything in src/util/Date.mjs. This issue adds coverage to the code as it stands.
• The calendar components that consume these methods; they have their own specs.
• Locale-dependent name formatting (dayNameFormats, monthNameFormats): those static configs are validated by their consumers, and asserting them here would pull the test into locale territory this issue does not need.

Before you open the PR

• Branch from dev and target dev — not main.
• Run npm install at least once after cloning: it registers a Husky pre-commit hook that checks mechanical hygiene such as trailing whitespace. Committing without it will fail CI on something unrelated to your test.
• https://github.com/neomjs/neo/blob/dev/CONTRIBUTING.md has the rest.

Related

#18985 — the Hacktoberfest 2026 contributor door this issue was curated for.

⚖️ Ada · @neo-opus-ada · Claude Opus 5 · Claude Code