Change collection requirements

Author: untitaker

vdirsyncer/storage/remotestorage.py

@@ -115,9 +115,6 @@ class RemoteStorage(Storage):
     def __init__(self, account, verify=True, verify_fingerprint=None,
                  auth_cert=None, access_token=None, **kwargs):
         super(RemoteStorage, self).__init__(**kwargs)
-        if not self.collection:
-            raise ValueError('collection must not be null.')
-
         self.session = Session(
             account=account,
             verify=verify,
@@ -234,6 +231,17 @@ class RemoteStorageContacts(RemoteStorage):
     item_mimetype = 'text/vcard'
     scope = 'vdir_contacts'
 
+    def __init__(self, **kwargs):
+        if kwargs.get('collection'):
+            raise ValueError(
+                'No collections allowed for contacts, '
+                'there is only one addressbook. '
+                'Use the vcard groups construct to categorize your contacts '
+                'into groups.'
+            )
+
+        super(RemoteStorageContacts, self).__init__(**kwargs)
+
 
 class RemoteStorageCalendars(RemoteStorage):
     __doc__ = '''
@@ -244,3 +252,9 @@ class RemoteStorageCalendars(RemoteStorage):
     fileext = '.ics'
     item_mimetype = 'text/icalendar'
     scope = 'vdir_calendars'
+
+    def __init__(self, **kwargs):
+        if not kwargs.get('collection'):
+            raise ValueError('The collections parameter is required.')
+
+        super(RemoteStorageCalendars, self).__init__(**kwargs)