Added missing serializers

src/Map.php

@@ -35,7 +35,7 @@
  * reference, of if a Map is used with foreach by reference, an exception will
  * be thrown.
  */
-class Map implements MapInterface, \ArrayAccess
+class Map implements MapInterface, \ArrayAccess, \JsonSerializable, \Serializable
 {
     use MapLikeTrait, SortTrait;
 

src/Set.php

@@ -30,7 +30,7 @@
  * is used when adding a new element to a Set (ex. "$c[] =& ..."), or if a Set
  * is used with foreach by reference, an exception will be thrown.
  */
-class Set implements SetInterface, \ArrayAccess
+class Set implements SetInterface, \ArrayAccess, \JsonSerializable, \Serializable
 {
     use SetLikeTrait;
 

src/Vector.php

@@ -30,7 +30,7 @@
  * passed by reference, of if a Vector is used with foreach by reference, an
  * exception will be thrown.
  */
-class Vector implements VectorInterface, \ArrayAccess
+class Vector implements VectorInterface, \ArrayAccess, \JsonSerializable, \Serializable
 {
     use VectorLikeTrait, SortTrait;
 

tests/CollectionSerializerTest.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Tests\Collections;
+
+use Collections\Map;
+use Collections\Queue;
+use Collections\Set;
+use Collections\Stack;
+use Collections\Vector;
+
+class CollectionSerializerTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @test
+     * @dataProvider collectionProvider
+     * @param $coll
+     * @param $expectedSerialization
+     */
+    public function is_should_json_serialize_it($coll, $expectedSerialization)
+    {
+        $serializedColl = json_encode($coll);
+        $this->assertJsonStringEqualsJsonString($serializedColl, $expectedSerialization);
+    }
+
+    /**
+     * @test
+     * @dataProvider collectionProvider
+     * @param $coll
+     */
+    public function is_should_php_serialize_it($coll)
+    {
+        $serializedColl = serialize($coll);
+        $this->assertInternalType("string", $serializedColl);
+        $collection = unserialize($serializedColl);
+        $this->assertInstanceOf(get_class($coll), $collection);
+    }
+
+    public function collectionProvider()
+    {
+        $data = [1, 2, 3, 4];
+
+        $queue = new Queue();
+        $queue->push(1);
+
+        $stack = new Stack();
+        $stack->push(1);
+
+        return [
+            [new Vector($data), '[1,2,3,4]'],
+            [new Set($data), '[1,2,3,4]'],
+            [new Map(['test' => 'test']), '{"test": "test"}'],
+            [$queue, '[1]'],
+            [$stack, '[1]'],
+        ];
+    }
+}