Add test for #918

We're doing something wrong with UID/href quoting/unquoting, but I've
yet to figure out what.

Author: Hugo Osvaldo Barrera

tests/storage/__init__.py

@@ -310,6 +310,26 @@ async def test_specialchars(
         if self.storage_class.storage_name.endswith("dav"):
             assert urlquote(uid, "/@:") in href
 
+    @pytest.mark.asyncio
+    async def test_newline_in_uid(
+        self, monkeypatch, requires_collections, get_storage_args, get_item
+    ):
+        monkeypatch.setattr("vdirsyncer.utils.generate_href", lambda x: x)
+
+        uid = "20210609T084907Z-@synaps-web-54fddfdf7-7kcfm%0A.ics"
+
+        s = self.storage_class(**await get_storage_args())
+        item = get_item(uid=uid)
+
+        href, etag = await s.upload(item)
+        item2, etag2 = await s.get(href)
+        if etag is not None:
+            assert etag2 == etag
+            assert_item_equals(item2, item)
+
+        ((_, etag3),) = await aiostream.stream.list(s.list())
+        assert etag2 == etag3
+
     @pytest.mark.asyncio
     async def test_empty_metadata(self, requires_metadata, s):
         if getattr(self, "dav_server", ""):