adds test for caching result set with file engine. References issue #10111 and this test is failing for me on PHP 7.1.1

Author: thinkingmedia

tests/TestCase/Cache/Engine/FileEngineTest.php

@@ -17,13 +17,27 @@
 use Cake\Cache\Cache;
 use Cake\Cache\Engine\FileEngine;
 use Cake\Core\Configure;
+use Cake\ORM\ResultSet;
+use Cake\ORM\TableRegistry;
 use Cake\TestSuite\TestCase;
+use TestApp\Model\Table\ArticlesTable;
 
 /**
  * FileEngineTest class
  */
 class FileEngineTest extends TestCase
 {
+    /**
+     * @var array
+     */
+    public $fixtures = [
+        'core.articles'
+    ];
+
+    /**
+     * @var bool
+     */
+    public $autoFixtures = false;
 
     /**
      * setUp method
@@ -192,6 +206,34 @@ public function testSerialize()
         $this->assertSame(unserialize($read), $data);
     }
 
+    /**
+     * Verify across PHP versions that caching of ResultSet objects works as expected.
+     *
+     * @see https://github.com/cakephp/cakephp/issues/10111
+     * @return void
+     */
+    public function testResultSetCache()
+    {
+        Configure::write('App.namespace', 'TestApp');
+        $this->loadFixtures('Articles');
+
+        /* @var ArticlesTable $articles */
+        $articles = TableRegistry::get('Articles');
+        $query = $articles->find()->all();
+        $this->assertInstanceOf(ResultSet::class, $query);
+        $this->assertSame(3, count($query->toArray()));
+
+        $this->_configCache(['serialize' => true]);
+        $write = Cache::write('articles', $query, 'file_test');
+        $this->assertTrue($write);
+
+        $read = Cache::read('articles', 'file_test');
+        $this->assertInstanceOf(ResultSet::class, $read);
+        $this->assertSame(3, count($read->toArray()));
+
+        TableRegistry::clear();
+    }
+
     /**
      * testClear method
      *