tp-spec 0.21.2 clarified that MessagePartSupportFlags, SupportedContentTypes and DeliveryReportingSupport are immutable.
As such, they should be in NewChannels.
Due to Bug #30949, DeliveryReportingSupport won't work reliably until we depend on telepathy-glib 0.13.3, so the tests don't test its value, only that it exists. There is a FIXME comment for that.
Thanks, fixed in git for 0.11.0. Here's a trivial branch to bring back the missing (bit of) test.
0.11.0, not worth backporting IMO