Updated tests/utils.py

tests/utils.py

@@ -41,7 +41,8 @@ def get_content_type(filename):
 
 
 def read_file(path, encoding='utf-8'):
-    data = open(path, 'rb').read()
+    with open(path, 'rb') as f:
+        data = f.read()
         if encoding is None:
             return data
         return data.decode(encoding)