Add XML parsing

src/CodePoint.php

@@ -103,9 +103,6 @@ public function toHtmlEntity(): string
 
     public function toXmlEntity(): string
     {
-        return htmlentities(
-            $this->toCharacter(),
-            ENT_XML1 | ENT_QUOTES | ENT_SUBSTITUTE,
-        );
+        return '&#x' . dechex($this->decimal) . ';';
     }
 }

test/Unit/CodePointTest.php

@@ -145,6 +145,10 @@ public function testItCanInstantiateOfXmlEntity(
         string $htmlEntity,
         string $xmlEntity
     ): void {
+        if ($xmlEntity === '�') {
+            $this->markTestSkipped('XML does not have NULL value');
+        }
+
         $codePoint = CodePoint::ofXmlEntity($xmlEntity);
 
         $this->assertSame(
@@ -253,18 +257,18 @@ public function testItCannotInstantiateOfXmlEntityWithMoreThanOneCharacter(): vo
     public static function provideUnicodeMap(): array
     {
         return [
-            ["\x00", 0, 'U+0000', "\x00", "\x00"],
-            ['􏿿', 1114111, 'U+10FFFF', '􏿿', '􏿿'],
-            [' ', 32, 'U+0020', ' ', ' '],
-            ['A', 65, 'U+0041', 'A', 'A'],
-            [' ', 160, 'U+00A0', ' ', ' '],
-            ['ÿ', 255, 'U+00FF', 'ÿ', 'ÿ'],
-            ['Ā', 256, 'U+0100', 'Ā', 'Ā'],
-            ['ſ', 383, 'U+017F', 'ſ', 'ſ'],
-            ['€', 8364, 'U+20AC', '€', '€'],
-            ['⚙', 9881, 'U+2699', '⚙', '⚙'],
-            ['👨', 128104, 'U+1F468', '👨', '👨'],
-            ['�', 65533, 'U+FFFD', '�', '�'],
+            ["\x00", 0, 'U+0000', "\x00", '�'],
+            ['􏿿', 1114111, 'U+10FFFF', '􏿿', ''],
+            [' ', 32, 'U+0020', ' ', ' '],
+            ['A', 65, 'U+0041', 'A', 'A'],
+            [' ', 160, 'U+00A0', ' ', ' '],
+            ['ÿ', 255, 'U+00FF', 'ÿ', 'ÿ'],
+            ['Ā', 256, 'U+0100', 'Ā', 'Ā'],
+            ['ſ', 383, 'U+017F', 'ſ', 'ſ'],
+            ['€', 8364, 'U+20AC', '€', '€'],
+            ['⚙', 9881, 'U+2699', '⚙', '⚙'],
+            ['👨', 128104, 'U+1F468', '👨', '👨'],
+            ['�', 65533, 'U+FFFD', '�', '�'],
         ];
     }
 }