Add unit tests for the user preferences validation and supported currency/language/timezone constants

[Baskarayelu]

📋 Description

The preferences write path validates input with utils/validation/preferences-validation.ts (validateCurrency, validateLanguage, validateNotificationsEnabled, validateTimezone, validatePreferencesUpdate) against the allow-lists in utils/constants/supported-values.ts (SUPPORTED_CURRENCIES, SUPPORTED_LANGUAGES, COMMON_TIMEZONES, DEFAULT_PREFERENCES). This is used by app/api/user/preferences/route.ts (PATCH). There is no test file for either.

Why this matters: preferences validation is the guard that keeps an unsupported currency or bogus locale out of the database and out of the currency formatter / i18n layer. A gap here surfaces later as broken formatting or a missing translation. Validation against a fixed allow-list is trivially testable and worth locking down.

🎯 Requirements & Context

Functional requirements

• Add tests/unit/preferences-validation.test.ts (Vitest).
• Assert each validator accepts every value in its allow-list and rejects out-of-list / wrong-type values (throwing the module's ValidationError).
• Assert validatePreferencesUpdate accepts a partial update, ignores undefined fields, and rejects when any provided field is invalid.
• Assert DEFAULT_PREFERENCES is internally consistent (its currency/language are members of the supported lists).
• Assert notifications_enabled rejects non-boolean inputs.

Context & constraints

• Vitest 4.0.18; pure-function tests, no I/O.
• Test-only unless a real validation gap is found (document it in the PR).

🛠️ Suggested Execution

1. Fork & branch

git checkout -b test/preferences-validation

2. Implement changes

• Add table-driven tests iterating the allow-lists; add a consistency check for defaults.

3. Test & commit

npm run test:coverage
npx tsc --noEmit

• Cover edge cases: empty string, wrong case (e.g. "usd" vs "USD"), null, numeric language, unknown timezone.

Example commit message

test(preferences): add coverage for preferences validation + supported values

Proves allow-list acceptance/rejection and DEFAULT_PREFERENCES consistency.

✅ Acceptance Criteria & Guidelines

Requirement	Target
All validators covered	Required
Defaults-consistency assertion	Required
Coverage of preferences validation	≥ 95% lines
npx tsc --noEmit, npm run lint clean	Required
Timeframe	96 hours from assignment

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Please comment when you pick this up so we can avoid duplicate work. 🚀

[Menjay7]

Hi! I came across this issue and would love to work on it. I have experience with similar tasks and I'm confident I can investigate, implement a clean solution, and thoroughly test it before submitting a PR. If the issue is still open, I would appreciate it if you could assign it to me. Thank you!

[Johnjnr1]

@Johnjnr1 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, I'd like to work on this issue! because I am very conversant with solving problems like this!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Johnjnr1 to this issue.

[Samaro1]

@Samaro1 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Gm gm boss, I would love to work on this issue. A satisfactory and efficient PR will be raised

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Samaro1 to this issue.