Nick Craig-Wood 7dd42c93cf fstests: check backends return accurate object fingerprints after writes ...

Layers which wrap backends, such as the hasher backend and the VFS
cache, use fs.Fingerprint to detect whether an object has changed.
This only works if the object a backend hands back from a write
operation is identical to the object a fresh listing returns. If a
backend keeps the source's nanosecond precision modtime in memory
while the server stores milliseconds, or omits a hash the server
knows, every fingerprint comparison fails and cached hashes or files
are silently invalidated.

The existing tests compared modtimes within f.Precision() so they
could not detect these sub-precision divergences.

Add a checkFingerprint helper which asserts the fast and slow
fs.Fingerprint of the object returned from a write operation exactly
match those of the object read back from the remote, and wire it into
all the write paths which return or mutate an object: Put (all
variants), PutStream, large and streamed uploads, Update, SetModTime,
server side Copy and Move, and the metadata mutating Copy/Move
subtests.

Rework the ObjectOpenFingerprint test to use the same helper against
a fully read reference object, with subtests reporting which kind of
read is being checked.

2026-07-13 13:40:53 +01:00

..

fstests.go

fstests: check backends return accurate object fingerprints after writes

2026-07-13 13:40:53 +01:00