Add $allowEmpty parameter to URL validator

[Copilot]

The URL validator had no way to permit empty values, making it impossible to use for optional URL fields without wrapping it.

Changes

• URL.php: Added bool $allowEmpty = false constructor parameter. When true, isValid() short-circuits to true for '' and null. Uses strict equality (=== '', === null) rather than empty() to avoid false positives on '0'/0.
• URLTest.php: Added testAllowEmpty() covering empty/null pass-through, valid URL still accepted, invalid non-empty URL still rejected, and default behavior (empty disallowed).

Usage

// Default — empty values rejected (no behaviour change)
$validator = new URL();
$validator->isValid('');  // false

// Opt-in — empty values allowed
$validator = new URL(allowEmpty: true);
$validator->isValid('');                   // true
$validator->isValid(null);                 // true
$validator->isValid('https://example.com'); // true
$validator->isValid('not-a-url');          // false

// Works alongside scheme restrictions
$validator = new URL(['https'], allowEmpty: true);

[Meldiron]

lgtm

[greptile-apps]

Greptile Summary

This PR adds an $allowEmpty parameter to the URL validator so optional URL fields can pass through without being wrapped. The implementation is largely sound, but there is a discrepancy between the documented behaviour and the code: the PR description states isValid(null) returns true when allowEmpty: true, yet the guard only checks $value === '', and the test asserts false for null even in the allowEmpty path. The intended handling of null needs to be settled and made consistent across the implementation, tests, and documentation.

Confidence Score: 3/5

Not safe to merge until the null behaviour is clarified and made consistent between implementation, tests, and PR description.

A P1 inconsistency exists between the documented contract (null returns true with allowEmpty: true) and the actual code + test (null returns false). This must be resolved before the change is reliable for callers who pass null to optional URL fields.

src/Validator/URL.php (line 56) and tests/Validator/URLTest.php (line 60) — both need to be updated once the intended null behaviour is decided.

Important Files Changed

Filename	Overview
src/Validator/URL.php	Adds $allowEmpty constructor parameter; null is not short-circuited despite being listed as allowed in the PR description.
tests/Validator/URLTest.php	New testAllowEmpty() added; assertion on line 60 contradicts the PR description's documented behaviour for null with allowEmpty: true.

_{Reviews (1): Last reviewed commit: "Apply suggestions from code review" | Re-trigger Greptile}