ResolvedDomain should handle domain with root label

Author: nyamsprod

src/DomainName.php

@@ -124,6 +124,4 @@ public function clear(): self;
      * If $length is null it returns all elements from $offset to the end of the Domain.
      */
     public function slice(int $offset, ?int $length = null): self;
-
-
 }

src/ResolvedDomain.php

@@ -10,17 +10,21 @@
 
 final class ResolvedDomain implements ResolvedDomainName
 {
+    private readonly DomainName $domain;
     private readonly DomainName $secondLevelDomain;
     private readonly DomainName $registrableDomain;
     private readonly DomainName $subDomain;
+    private readonly EffectiveTopLevelDomain $suffix;
 
     /**
      * @throws CannotProcessHost
      */
     private function __construct(
-        private readonly DomainName $domain,
-        private readonly EffectiveTopLevelDomain $suffix
+        DomainName $domain,
+        EffectiveTopLevelDomain $suffix
     ) {
+        $this->domain = $domain;
+        $this->suffix = $suffix;
         [
             'registrableDomain' => $this->registrableDomain,
             'secondLevelDomain' => $this->secondLevelDomain,
@@ -195,8 +199,10 @@ public function withSuffix(DomainNameProvider|Host|Stringable|string|int|null $s
             $suffix = Suffix::fromUnknown($suffix);
         }
 
+        $newDomain = $this->domain->withoutRootLabel()->slice(count($this->suffix))->append($suffix);
+
         return new self(
-            $this->domain->slice(count($this->suffix))->append($suffix),
+            $this->domain->isAbsolute() ? $newDomain->withRootLabel() : $newDomain,
             $suffix->normalize($this->domain)
         );
     }
@@ -211,6 +217,10 @@ public function withSubDomain(DomainNameProvider|Host|Stringable|string|int|null
         }
 
         $subDomain = RegisteredName::fromIDNA2008($subDomain);
+        if ('' === $subDomain->withoutRootLabel()->value()) {
+            throw SyntaxError::dueToMalformedValue($subDomain->toString());
+        }
+
         if ($this->subDomain->value() === $subDomain->value()) {
             return $this;
         }

src/ResolvedDomainTest.php

@@ -322,6 +322,7 @@ public function testItCanChangeItsSuffix(
     public static function withPublicSuffixWorksProvider(): iterable
     {
         $baseDomain = ResolvedDomain::fromICANN('example.com', 1);
+        $baseRootDomain = ResolvedDomain::fromICANN('example.com.', 1);
 
         return [
             'simple update (1)' => [
@@ -332,6 +333,14 @@ public static function withPublicSuffixWorksProvider(): iterable
                 'isICANN' => false,
                 'isPrivate' => false,
             ],
+            'simple update with root-label (1)' => [
+                'domain' => $baseRootDomain,
+                'publicSuffix' => 'be',
+                'expected' => 'be',
+                'isKnown' => false,
+                'isICANN' => false,
+                'isPrivate' => false,
+            ],
             'simple update (2)' => [
                 'domain' => $baseDomain,
                 'publicSuffix' => Suffix::fromPrivate('github.io'),
@@ -340,6 +349,14 @@ public static function withPublicSuffixWorksProvider(): iterable
                 'isICANN' => false,
                 'isPrivate' => true,
             ],
+            'simple update with root-label (2)' => [
+                'domain' => $baseRootDomain,
+                'publicSuffix' => Suffix::fromPrivate('github.io'),
+                'expected' => 'github.io',
+                'isKnown' => true,
+                'isICANN' => false,
+                'isPrivate' => true,
+            ],
             'same public suffix but PSL info is changed' => [
                 'domain' => $baseDomain,
                 'publicSuffix' => Suffix::fromPrivate('com'),
@@ -348,6 +365,14 @@ public static function withPublicSuffixWorksProvider(): iterable
                 'isICANN' => false,
                 'isPrivate' => true,
             ],
+            'same public suffix but PSL info is changed with root domain' => [
+                'domain' => $baseRootDomain,
+                'publicSuffix' => Suffix::fromPrivate('com'),
+                'expected' => 'com',
+                'isKnown' => true,
+                'isICANN' => false,
+                'isPrivate' => true,
+            ],
             'same public suffix but PSL info does not changed' => [
                 'domain' => $baseDomain,
                 'publicSuffix' => Suffix::fromICANN('com'),
@@ -372,6 +397,14 @@ public static function withPublicSuffixWorksProvider(): iterable
                 'isICANN' => true,
                 'isPrivate' => false,
             ],
+            'simple update IDN (2) with root domains' => [
+                'domain' => ResolvedDomain::fromICANN(Domain::fromIDNA2003('www.bébé.be.'), 1),
+                'publicSuffix' => Suffix::fromICANN(Domain::fromIDNA2003('xn--p1ai')),
+                'expected' => 'рф',
+                'isKnown' => true,
+                'isICANN' => true,
+                'isPrivate' => false,
+            ],
             'adding the public suffix to a single label domain' => [
                 'domain' => ResolvedDomain::fromUnknown('localhost'),
                 'publicSuffix' => 'www',