Merge pull request paquettg#193 from rikvdh/issue-191

Fix for issue 191

Author: paquettg

src/PHPHtmlParser/Selector/Selector.php

@@ -354,7 +354,7 @@ public function checkComparison(array $rule, AbstractNode $node): bool
 
         // handle multiple classes
         if ( ! $check && $rule['key'] == 'class') {
-            $nodeClasses = explode(' ', $node->getAttribute('class'));
+            $nodeClasses = explode(' ', $node->getAttribute('class') ?? '');
             foreach ($rule['value'] as $value) {
                 foreach ($nodeClasses as $class) {
                     if ( ! empty($class)) {

tests/DomTest.php

@@ -483,4 +483,14 @@ public function testCaseSensitivity()
         $FooBar = $dom->find('FooBar');
         $this->assertEquals('asdf', $FooBar->Attribute);
     }
+
+    public function testEmptyAttribute()
+    {
+        $str = '<ul class="summary"><li class></li>blah<li class="foo">what</li></ul>';
+        $dom = new Dom();
+        $dom->load($str);
+
+        $items = $dom->find('.summary .foo');
+        $this->assertEquals(1, count($items));
+    }
 }