Full-matrix on-device test (FullSyncEngineTest) drives the real SyncEngine
(in-memory Room + real local folder + live Nextcloud) across all directions,
all delete behaviors, updates, recursive/non-recursive, filters, conflicts,
and content integrity — 14 instrumented tests, all green on a Galaxy S23.
It caught a real bug: ARCHIVE delete moved files to _Deleted/ but never
created the _Deleted folder, so the MOVE failed for top-level files and they
were left in place. Now creates the _Deleted base before the move.
Instrumented test driving the real NextcloudProvider over TLS: connect,
create dir, atomic upload (temp+MOVE), list+size, download+content, then the
backup guarantee — Upload-only + KEEP yields SKIP and the cloud copy is
verified still present; MIRROR yields DELETE_REMOTE and the real delete is
confirmed. Creds passed via instrumentation args (ncUrl/ncUser/ncPass), never
committed. Verified passing on a Galaxy S23 (Android 16) against live Nextcloud.
amir