style cleanup

break out header parts in test
test for no filename* parameter for ascii header

flask/helpers.py

@@ -14,10 +14,10 @@ import sys
 import pkgutil
 import posixpath
 import mimetypes
-from unicodedata import normalize
 from time import time
 from zlib import adler32
 from threading import RLock
+import unicodedata
 from werkzeug.routing import BuildError
 from functools import update_wrapper
 
@@ -478,6 +478,11 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
     .. versionchanged:: 0.12
        The `attachment_filename` is preferred over `filename` for MIME-type
        detection.
+       
+    .. versionchanged:: 0.13
+        UTF-8 filenames, as specified in `RFC 2231`_, are supported.
+        
+    .. _RFC 2231: https://tools.ietf.org/html/rfc2231#section-4
 
     :param filename_or_fp: the filename of the file to send in `latin-1`.
                            This is relative to the :attr:`~Flask.root_path`
@@ -535,7 +540,10 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
         if attachment_filename is None:
             raise TypeError('filename unavailable, required for '
                             'sending as attachment')
-        normalized = normalize('NFKD', text_type(attachment_filename))
+
+        normalized = unicodedata.normalize(
+            'NFKD', text_type(attachment_filename)
+        )
 
         try:
             normalized.encode('ascii')
@@ -545,12 +553,9 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
                 'filename*': "UTF-8''%s" % url_quote(attachment_filename),
             }
         else:
-            filenames = {
-                'filename': attachment_filename,
-            }
+            filenames = {'filename': attachment_filename}
 
-        headers.add('Content-Disposition', 'attachment',
-                    **filenames)
+        headers.add('Content-Disposition', 'attachment', **filenames)
 
     if current_app.use_x_sendfile and filename:
         if file is not None: