From ed22764921b2e5bf6a934cf14aa9c5fede804d8e Mon Sep 17 00:00:00 2001
From: Markus Unterwaditzer <markus@unterwaditzer.net>
Date: Fri, 13 Nov 2015 22:54:26 +0100
Subject: [PATCH] Fix bug during prefetch

The idea that prefetching isn't necessary if the other storage can't be
written to is wrong, we still need to prefetch for UID-matching
---
 tests/test_sync.py | 17 +++++++++++++++++
 vdirsyncer/sync.py |  8 ++++----
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/tests/test_sync.py b/tests/test_sync.py
index 6ea36b6..9c4f3cb 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -41,6 +41,7 @@ def test_missing_status():
 def test_missing_status_and_different_items():
     a = MemoryStorage()
     b = MemoryStorage()
+
     status = {}
     item1 = Item(u'UID:1\nhaha')
     item2 = Item(u'UID:1\nhoho')
@@ -54,6 +55,22 @@ def test_missing_status_and_different_items():
     assert_item_equals(item1, a.get('1')[0])
 
 
+def test_read_only_and_prefetch():
+    a = MemoryStorage()
+    b = MemoryStorage()
+    b.read_only = True
+
+    status = {}
+    item1 = Item(u'UID:1\nhaha')
+    item2 = Item(u'UID:2\nhoho')
+    a.upload(item1)
+    a.upload(item2)
+
+    sync(a, b, status, force_delete=True)
+    sync(a, b, status, force_delete=True)
+
+    assert list(a.list()) == list(b.list()) == []
+
 def test_upload_and_update():
     a = MemoryStorage(fileext='.a')
     b = MemoryStorage(fileext='.b')
diff --git a/vdirsyncer/sync.py b/vdirsyncer/sync.py
index 88df95a..ef66d0c 100644
--- a/vdirsyncer/sync.py
+++ b/vdirsyncer/sync.py
@@ -87,7 +87,7 @@ class StorageSyncer(object):
         self.status = status
         self.idents = None
 
-    def prepare_idents(self, other_read_only):
+    def prepare_idents(self):
         href_to_status = dict((href, (ident, etag))
                               for ident, (href, etag)
                               in iteritems(self.status))
@@ -105,7 +105,7 @@ class StorageSyncer(object):
             props = {'href': href, 'etag': etag}
             ident, old_etag = href_to_status.get(href, (None, None))
             assert etag is not None
-            if etag != old_etag and not other_read_only:
+            if etag != old_etag:
                 # Either the item is completely new, or updated
                 # In both cases we should prefetch
                 prefetch[href] = props
@@ -165,8 +165,8 @@ def sync(storage_a, storage_b, status, conflict_resolution=None,
         for ident, (href_a, etag_a, href_b, etag_b) in iteritems(status)
     ))
 
-    a_info.prepare_idents(storage_b.read_only)
-    b_info.prepare_idents(storage_a.read_only)
+    a_info.prepare_idents()
+    b_info.prepare_idents()
 
     if bool(a_info.idents) != bool(b_info.idents) \
        and status and not force_delete: