Update type hints, improve test assertions, and raise PHP requirement.

The code now uses nullable type hints for better clarity and stricter type enforcement. The deprecated assertInternalType method is replaced with assertIsInt in tests to ensure compatibility with newer PHPUnit versions. The minimum required PHP version in the composer.json file is increased to 7.1 due to the use of nullable type hints, which are incompatible with PHP 5.6.

composer.json

@@ -22,7 +22,7 @@
     "source": "https://github.com/vanderlee/phpSyllable/"
   },
   "require": {
-    "php": ">=5.6",
+    "php": ">=7.1",
     "ext-json": "*",
     "ext-libxml": "*",
     "ext-mbstring": "*",

src/Syllable.php

@@ -162,7 +162,7 @@ public function getHyphen()
     /**
      * @param Cache $cache
      */
-    public function setCache(Cache $cache = null)
+    public function setCache(?Cache $cache = null)
     {
         $this->cache = $cache;
     }
@@ -598,8 +598,8 @@ private function parseHtmlText($html)
      */
     private function hyphenateHtmlDom(
         DOMNode $node,
-        DOMNodeList $excludeNodes = null,
-        DOMNodeList $includeNodes = null,
+        ?DOMNodeList $excludeNodes = null,
+        ?DOMNodeList $includeNodes = null,
         $split = true
     ) {
         if ($node->hasChildNodes()) {

tests/src/SyllableTest.php

@@ -171,8 +171,8 @@ public function testCache($cacheClass, $language, $cacheDirectory, $cacheFile, $
         $this->assertNotEmpty($this->object->getCache()->__get('patterns'));
         $this->assertGreaterThan(0, $this->object->getCache()->__get('max_pattern'));
         $this->assertNotEmpty($this->object->getCache()->__get('hyphenation'));
-        $this->assertInternalType('int', $this->object->getCache()->__get('left_min_hyphen'));
-        $this->assertInternalType('int', $this->object->getCache()->__get('right_min_hyphen'));
+        $this->assertIsInt($this->object->getCache()->__get('left_min_hyphen'));
+        $this->assertIsInt($this->object->getCache()->__get('right_min_hyphen'));
     }
 
     public function dataCacheVersionMatchesCacheFileVersionIsRelaxed()