Add test to assert the value of a dequeued element

tests/DataStructures/QueueTest.php

@@ -35,6 +35,21 @@ public function shouldRemoveElementFromQueue(): void
         $this->assertEquals(2, $queue->size());
     }
 
+    /**
+     * @test
+     */
+    public function shouldReturnCorrectValueWhenDequeue(): void
+    {
+        $queue = new Queue();
+        $queue->enqueue(1);
+        $queue->enqueue(2);
+        $queue->enqueue(3);
+
+        $this->assertEquals(1, $queue->dequeue());
+        $this->assertEquals(2, $queue->dequeue());
+        $this->assertEquals(3, $queue->dequeue());
+    }
+
     /**
      * @test
      */