Make etags always strings.

This somewhat helps with environments where ducktyping is not an option
(e.g. databases)

tests/storage/__init__.py

@@ -41,6 +41,8 @@ class StorageTests(object):
         hrefs.sort()
         assert hrefs == sorted(s.list())
         for href, etag in hrefs:
+            assert isinstance(href, (str, unicode))
+            assert isinstance(etag, (str, unicode))
             assert s.has(href)
             obj, etag2 = s.get(href)
             assert etag == etag2

vdirsyncer/storage/base.py

@@ -36,6 +36,9 @@ class Storage(object):
       - ETAG: Checksum of item, or something similar that changes when the
           object does.
 
+    All of the above properties should be strings. If bytestrings, an ASCII
+    encoding is assumed.
+
     :param collection: If None, the given URL or path is already directly
         referring to a collection. Otherwise it will be treated as a basepath
         to many collections (e.g. a vdir) and the given collection name will be

vdirsyncer/storage/filesystem.py

@@ -15,6 +15,10 @@ import vdirsyncer.log as log
 logger = log.get('storage.filesystem')
 
 
+def _get_etag(fpath):
+    return '{:.9f}'.format(os.path.getmtime(fpath))
+
+
 class FilesystemStorage(Storage):
 
     '''Saves data in vdir collection
@@ -61,13 +65,13 @@ class FilesystemStorage(Storage):
         for fname in os.listdir(self.path):
             fpath = os.path.join(self.path, fname)
             if os.path.isfile(fpath) and fname.endswith(self.fileext):
-                yield fname, os.path.getmtime(fpath)
+                yield fname, _get_etag(fpath)
 
     def get(self, href):
         fpath = self._get_filepath(href)
         with open(fpath, 'rb') as f:
             return (Item(f.read().decode(self.encoding)),
-                    os.path.getmtime(fpath))
+                    _get_etag(fpath))
 
     def has(self, href):
         return os.path.isfile(self._get_filepath(href))
@@ -79,7 +83,7 @@ class FilesystemStorage(Storage):
             raise exceptions.AlreadyExistingError(obj.uid)
         with open(fpath, 'wb+') as f:
             f.write(obj.raw.encode(self.encoding))
-        return href, os.path.getmtime(fpath)
+        return href, _get_etag(fpath)
 
     def update(self, href, obj, etag):
         fpath = self._get_filepath(href)
@@ -88,19 +92,19 @@ class FilesystemStorage(Storage):
                            .format(href, obj.uid))
         if not os.path.exists(fpath):
             raise exceptions.NotFoundError(obj.uid)
-        actual_etag = os.path.getmtime(fpath)
+        actual_etag = _get_etag(fpath)
         if etag != actual_etag:
             raise exceptions.WrongEtagError(etag, actual_etag)
 
         with open(fpath, 'wb') as f:
             f.write(obj.raw.encode('utf-8'))
-        return os.path.getmtime(fpath)
+        return _get_etag(fpath)
 
     def delete(self, href, etag):
         fpath = self._get_filepath(href)
         if not os.path.isfile(fpath):
             raise exceptions.NotFoundError(href)
-        actual_etag = os.path.getmtime(fpath)
+        actual_etag = _get_etag(fpath)
         if etag != actual_etag:
             raise exceptions.WrongEtagError(etag, actual_etag)
         os.remove(fpath)

vdirsyncer/storage/memory.py

@@ -7,11 +7,15 @@
     :license: MIT, see LICENSE for more details.
 '''
 
-import datetime
+import random
 from vdirsyncer.storage.base import Storage
 import vdirsyncer.exceptions as exceptions
 
 
+def _get_etag():
+    return '{:.9f}'.format(random.random())
+
+
 class MemoryStorage(Storage):
 
     '''
@@ -37,7 +41,7 @@ class MemoryStorage(Storage):
         href = self._get_href(obj.uid)
         if href in self.items:
             raise exceptions.AlreadyExistingError(obj.uid)
-        etag = datetime.datetime.now()
+        etag = _get_etag()
         self.items[href] = (etag, obj)
         return href, etag
 
@@ -48,7 +52,7 @@ class MemoryStorage(Storage):
         if etag != actual_etag:
             raise exceptions.WrongEtagError(etag, actual_etag)
 
-        new_etag = datetime.datetime.now()
+        new_etag = _get_etag()
         self.items[href] = (new_etag, obj)
         return new_etag