Improve code, fix filesystem test failing after first run

test/Unit/Adapter/FilesystemAdapterTest.php

@@ -6,6 +6,8 @@ namespace IQParts\CacheTest\Unit\Adapter;
 use IQParts\Cache\Adapter\FilesystemAdapter;
 use IQParts\Cache\Serializer\JsonSerializer;
 use IQParts\CacheTest\AbstractTestCase;
+use RecursiveDirectoryIterator;
+use RecursiveIteratorIterator;
 
 final class FilesystemAdapterTest extends AbstractTestCase
 {
@@ -27,7 +29,7 @@ final class FilesystemAdapterTest extends AbstractTestCase
 
         $adapter->set('ttl', 'b', 200);
         $this->assertTrue($adapter->ttl('ttl') > 0);
-        $this->assertTrue($adapter->ttl('b') === $adapter::NO_TTL);
+        $this->assertSame($adapter->ttl('b'), $adapter::NO_TTL);
 
         $adapter->set('a-keys', 'a');
         $adapter->set('b-keys', 'a');
@@ -118,4 +120,22 @@ final class FilesystemAdapterTest extends AbstractTestCase
         $this->assertEquals('a', $adapter->get('a/b'));
         $adapter->delete('a/b');
     }
+
+    protected function tearDown()
+    {
+        parent::tearDown();
+        $files = new RecursiveIteratorIterator(
+            new RecursiveDirectoryIterator($this->getTmpDirectory(), RecursiveDirectoryIterator::SKIP_DOTS),
+            RecursiveIteratorIterator::CHILD_FIRST
+        );
+
+        foreach ($files as $file) {
+            if ($file->isDir()) {
+                rmdir($file->getRealPath());
+            } else {
+                unlink($file->getRealPath());
+            }
+        }
+    }
+
 }