Added NONE extensions configuration

CHANGELOG.rst

@@ -7,6 +7,7 @@ Current
 - Added backend level configuration ``FS_{BACKEND_NAME}_{KEY}``
 - Improved backend documentation
 - Use setuptools entry points to register backends.
+- Added `NONE` extensions specification
 
 0.3.0 (2017-03-05)
 ------------------

flask_fs/files.py

@@ -5,7 +5,7 @@
 
 __all__ = (
     'TEXT', 'DOCUMENTS', 'IMAGES', 'AUDIO', 'DATA', 'SCRIPTS', 'ARCHIVES', 'EXECUTABLES',
-    'DEFAULTS', 'ALL', 'All', 'AllExcept',
+    'DEFAULTS', 'ALL', 'NONE', 'All', 'AllExcept', 'DisallowAll'
 )
 
 #: This just contains plain text files (.txt).
@@ -76,9 +76,21 @@ def __contains__(self, item):
         return True
 
 
+class DisallowAll(object):
+    '''
+    This type can be used to disallow all extensions.
+    There is a predefined instance named `NONE`.
+    '''
+    def __contains__(self, item):
+        return False
+
+
 #: This "contains" all items. You can use it to allow all extensions to be uploaded.
 ALL = All()
 
+#: This "contains" no items. You can use it to force a whitelist by configuration.
+NONE = DisallowAll()
+
 
 class AllExcept(object):
     '''

tests/test_config.py

@@ -5,7 +5,7 @@
 
 from flask import url_for
 
-from flask_fs import Storage, DEFAULTS
+from flask_fs import Storage, DEFAULTS, NONE
 from flask_fs.backends.local import LocalBackend
 
 
@@ -106,3 +106,9 @@ def test_configuration_cascading(app):
     assert avatars.base_url == 'http://somewhere-else.net/avatars/'
     assert images.base_url == 'http://somewhere.net/test/images/'
     assert images.config.endpoint == 'http://localhost:9000'
+
+
+def test_configurable_extensions(app):
+    files = Storage('files', NONE)
+    app.configure(files, FS_ALLOW=['txt'])
+    assert files.extension_allowed('txt')

tests/test_files.py

@@ -25,6 +25,13 @@ def test_lowercase_ext():
 def test_all():
     assert 'txt' in files.ALL
     assert 'exe' in files.ALL
+    assert 'any' in files.ALL
+
+
+def test_none():
+    assert 'txt' not in files.NONE
+    assert 'exe' not in files.NONE
+    assert 'any' not in files.NONE
 
 
 def test_all_except():