Fix count increment on insert in PriorityList

This patch fixes an issue with count incrementation in PriorityList, ensuring
incrementation only occurs if the item was not previously in the list.

Author: JoshVee

src/PriorityList.php

@@ -62,8 +62,11 @@ class PriorityList implements Iterator, Countable
      */
     public function insert($name, $value, $priority = 0)
     {
+        if (!isset($this->items[$name])) {
+            $this->count++;
+        }
+
         $this->sorted = false;
-        $this->count++;
 
         $this->items[$name] = array(
             'data'     => $value,

test/PriorityListTest.php

@@ -35,6 +35,24 @@ public function testInsert()
         }
     }
 
+    public function testInsertDuplicates()
+    {
+        $this->list->insert('foo', new \stdClass());
+        $this->list->insert('bar', new \stdClass());
+
+        $this->assertEquals(2, count($this->list));
+
+        $this->list->insert('foo', new \stdClass());
+        $this->list->insert('foo', new \stdClass());
+        $this->list->insert('bar', new \stdClass());
+
+        $this->assertEquals(2, count($this->list));
+
+        $this->list->remove('foo');
+
+        $this->assertEquals(1, count($this->list));
+    }
+
     public function testRemove()
     {
         $this->list->insert('foo', new \stdClass(), 0);