feat(Domain): add allowEmpty constructor option

src/Validator/Domain.php

@@ -18,7 +18,8 @@ class Domain extends Validator
      */
     public function __construct(
         protected array $restrictions = [],
-        protected bool $hostnames = true
+        protected bool $hostnames = true,
+        protected bool $allowEmpty = false
     ) {
     }
 
@@ -64,6 +65,10 @@ public function getDescription(): string
      */
     public function isValid($value): bool
     {
+        if ($this->allowEmpty && $value === '') {
+            return true;
+        }
+
         if (empty($value)) {
             return false;
         }

tests/Validator/DomainTest.php

@@ -120,6 +120,30 @@ public function testInvalidDomainsWithHostnamesFalse()
         $this->assertSame(true, $permissiveValidator->isValid('example.com/path')); // Path
     }
 
+    /**
+     * Test allowEmpty parameter
+     */
+    public function testAllowEmpty()
+    {
+        // By default, empty string is invalid
+        $this->assertSame(false, $this->domain->isValid(''));
+
+        // With allowEmpty=true, empty string is valid
+        $domainAllowEmpty = new Domain([], true, true);
+        $this->assertSame(true, $domainAllowEmpty->isValid(''));
+
+        // null is still invalid even with allowEmpty=true
+        $this->assertSame(false, $domainAllowEmpty->isValid(null));
+
+        // Valid domains still pass with allowEmpty=true
+        $this->assertSame(true, $domainAllowEmpty->isValid('example.com'));
+        $this->assertSame(true, $domainAllowEmpty->isValid('subdomain.example.com'));
+
+        // Invalid domains still fail with allowEmpty=true
+        $this->assertSame(false, $domainAllowEmpty->isValid('invalid..domain'));
+        $this->assertSame(false, $domainAllowEmpty->isValid(1));
+    }
+
     public function testRestrictions()
     {
         $validator = new Domain([