diff --git a/tests/Transformer/FormatTransformerTest.php b/tests/Transformer/FormatTransformerTest.php
new file mode 100644
index 0000000..3548355
--- /dev/null
+++ b/tests/Transformer/FormatTransformerTest.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace Tests\AppBundle\Transformer;
+
+use AppBundle\Transformer\FormatTransformer;
+use PHPUnit\Framework\TestCase;
+
+class FormatTransformerTest extends TestCase
+{
+    /**
+     * @var FormatTransformer
+     */
+    private $transformer;
+
+    protected function setUp()
+    {
+        $this->transformer = new FormatTransformer();
+    }
+
+    public function testBytesToSize() {
+        $this->assertEquals('1.5 MB', $this->transformer->bytesToSize(512*1024+1024*1024, 2));
+        $this->assertEquals('512 B', $this->transformer->bytesToSize(512, 2));
+        $this->assertEquals('1 KB', $this->transformer->bytesToSize(1024, 2));
+        $this->assertEquals('1 MB', $this->transformer->bytesToSize(1024*1024, 2));
+        $this->assertEquals('1 GB', $this->transformer->bytesToSize(1024*1024*1024, 2));
+        $this->assertEquals('1 TB', $this->transformer->bytesToSize(1024*1024*1024*1024, 2));
+    }
+}