proton-drive-linux/docs/TESTING.md

# Testing

The normal Rust suite exercises the metadata database, sync planner, offline
queue, write staging, cache, and FUSE handler state without requiring a Proton
account:

```console
cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings
```

## Filesystem API and live FUSE acceptance suite

The account-free suite exercises the filesystem syscall contract against a
temporary local directory. This validates the runner and covers creation/open
flags, positioned and vectored I/O, truncation and sparse files, `mmap`,
`sendfile`, `copy_file_range`, durability barriers, namespace/error semantics,
`renameat2` flags, open-file lifetime, names and enumeration, readdir stability
under concurrent mutation, metadata updates, extended attributes, allocation and
punched holes, refusal semantics for unimplemented operations, concurrent I/O,
and real application workloads. It never reads application state or contacts
Proton:

```console
scripts/fuse-acceptance.sh --offline-only
```

Kernel/FUSE behavior and remote convergence need a real mount. With no
arguments, the script tests the account the running service is logged in to:

```console
scripts/fuse-acceptance.sh           # every case, every mount kind
scripts/fuse-acceptance.sh --quick   # one on-demand/mirror pair instead of four
```

An account run does this, in order:

1. Runs the account-free contract as the reference.
2. Runs the contract in a fresh `pdfs-acceptance-<id>` folder in My files and
   diffs it against the reference.
3. Registers two new sync folders under `~/.cache/pdfs-acceptance/run-<id>/`
   and runs the contract and the move cases in every on-demand/mirror pairing.
4. Removes everything it created, locally and remotely, and reports a
   `cleanup` result. The run fails if anything is left behind.

Cleanup identifies remote folders by uid, never by name alone, so nothing of
yours is touched. It removes each sync folder with `sync rm --delete-remote`,
trashes the My files folder, and then deletes both permanently from the trash.
It only counts a folder as gone once a fresh trash listing no longer shows it.
It then reads `pdfs sync queue` and counts any queued op that still names one
of its folders as left behind too, since such an op keeps its staged bytes and
retries forever (B102).
Cleanup also runs on a failure, Ctrl-C, `SIGTERM` or `SIGHUP`. While it runs,
two more interrupts are ignored; a third abandons it.

Each run records what it is about to create in
`~/.cache/pdfs-acceptance/run-<id>/manifest.json` before it creates it, and
holds a lock on that directory. If a run dies without cleaning up (`kill -9`, a
hard timeout, a power cut), the next run finds the unlocked manifest and
finishes that cleanup first. It then removes stray `pdfs-acceptance-<32 hex>`
folders that no live run claims: in My files (older than
`PDFS_ACCEPTANCE_REAP_AGE`, default one hour), under the acceptance home, and
in the trash. A run does not start while that reap leaves anything behind.

The run creates and destroys real remote folders, so a dedicated test account
without irreplaceable data is still the safest target.

`--live PATH...` tests mounts you set up yourself and leaves the sync folder
configuration alone. It runs destructive POSIX operations only below a fresh
`pdfs-acceptance-*` directory, refuses paths that are not FUSE mounts, and
removes its directory on success, failure, or interruption:

```console
scripts/fuse-acceptance.sh --live /mnt/on-demand-testmount
```

### Edge cases and performance

Besides the syscall contract, the suite covers:

- **Block boundaries.** Files of 0 bytes up to two 4 MiB blocks plus 3 bytes,
  including every size next to a boundary, then overwrites that grow, shrink
  and reshape them.
- **Unusual names.** A 255-byte name, NFC and NFD forms of the same text,
  newline, tab, emoji, characters Windows forbids, leading and trailing
  spaces, and a case-only rename.
- **A deep tree and a wide directory.** 24 levels of nesting renamed at the
  top; 128 entries created concurrently, concurrent unlinks, then `rm -rf`.
  Online, each create is a round trip to the server, and the kernel runs
  creates in one directory one at a time. So the wide case gets twice the
  per-case timeout and notes the time per create as `wide.create_ms`.
- **Rename patterns.** Swaps, chains, log rotation, replacing a file under an
  open reader, the `EISDIR`/`ENOTDIR`/`ENOENT` refusals, and a folder moved out
  and back.
- **Handle coherency.** Unsynced writes seen by a second handle, two `O_APPEND`
  writers, 30 rewrite generations, and a truncate under a reader.
- **Throughput.** 64 MiB written and read sequentially, 1 MiB in 4 KiB writes,
  and metadata operations on 100 files. The rates are printed. The case fails
  below `PDFS_ACCEPTANCE_MIN_MIBPS` (default 10) or `PDFS_ACCEPTANCE_MIN_OPS`
  (default 20 operations per second).

### The mount is diffed against an ordinary filesystem

The local reference run is not only a self-test of the runner. Every case
records the facts it established, and a live run is compared against those
recordings, so a case fails when the mount *differs* from an ordinary
filesystem — not only when it raises. The report names the exact key:

```
  [DIVERGENCE] live FUSE /mnt/testmount does not match the reference filesystem:
    ! creation and open flags.truncated.size: live=6 reference=0
```

Facts are recorded in one of two ways, chosen in the test body:

- **compared** — a claim about filesystem semantics. The mount must agree.
- **noted** — context that legitimately differs: inode numbers, block counts,
  reported mode bits, and which optional syscalls exist at all. Reported under
  `[capabilities]`, never a failure.

Because the choice is made at each call site, the set of accepted divergences
is visible in the test that accepts it. There is no separate allowlist to drift
out of date. When adding a case, prefer `record`; reach for `note` only when an
ordinary filesystem can do something a network filesystem genuinely cannot.

### Operations the filesystem does not implement

`git`, `rsync`, `cp -a`, `tar`, `df` and most installers probe for symlinks,
hard links, FIFOs, device nodes, `statfs`, file locks, `copy_file_range`,
`O_DIRECT` and `SEEK_HOLE` whether or not a filesystem offers them. The suite
asserts that each either works or is *refused cleanly* — a recognised errno,
never `EIO` and never a hang. A refusal that is merely unimplemented is fine;
one that is dirty breaks software that never asked for the feature.

### Regressions from the bug ledger

Cases named `regression B<n>` reproduce a bug from `docs/BUGS.md` so it stays
fixed. B69 (identical rewrite must not fork a `(sync-conflict …)` copy), B70 (an
in-flight `.crdownload` must not be sealed as a revision) and B74 (a file
renamed after close must keep its content) need a real mount and a reachable
daemon; they are skipped, not failed, without one.

**B100** (a copied tree reads back at its exact sizes) copies 48 files of
assorted sizes into the mount at once, as `cp -r` does. On a live mount it
waits for the queue, checks every size and byte, runs `pdfs refresh` on each
folder to drop the cached listing, and checks again. The refresh is what
brought back the provisional sizes the bug reported.

**B101** (a write during its create's upload reaches Drive) holds new files open for
different times before writing, so their empty creates land before, during and after the
bytes arrive, then checks every file after the queue drains.

B74 was found by exactly this mechanism: the B70 case failed, and narrowing it
produced a smaller reproduction that got its own case. The defect is fixed and
live-validated (2026-07-26); the case now guards against its return.

**B79** (an on-demand device folder accepts writes) discovers its target from
`pdfs locations --json` and skips when this machine has no mounted on-demand
folder. It is the cheap standing guard against a *cross-mount* permission
regression: the primary mount holds device-folder nodes too, and the queue guard
intersects what every live inode space says about a uid, so a fail-closed
classification in one mount denies writes in another.

**B34** (a viewer-role share is read-only) and **B34b** (an editor-role share
still writes) locate their subject through `pdfs shared-with-me --json`, which
now carries `role` and a mount-relative `path`. Both skip when the account has no
accepted share at that role — B34 needs a **second account** to have shared a
folder read-only, which is the one part of the sharing suite that cannot be
self-served. B34b degrades gracefully in the other direction: a shared *file*
gets its mode bits and `W_OK` checked but is never written to, because it is
someone else's document.

B34's fourth assertion is the load-bearing one: `pending_uploads` and
`pending_changes` must be **unchanged** across the refused writes. Mode bits
alone would pass a fix that still admitted the write into `pending_op`, which is
the actual harm — a background drain failing 403 forever.

**Synthetic `Shared with me/` directory contract** asserts the virtual directory
enumerates, reports `0555`, and refuses `mkdir`/`rmdir`/`rename`. It skips when
the directory is absent (an account with no accepted shares).

A regression case asserts against the *remote* outcome, so it must wait for the
queue to drain before reading. Reading straight back through the mount proves
nothing: the local attribute and content caches will happily return the bytes
that were just written even when nothing reached Drive, which is precisely how
B74 stayed invisible.

### Timeouts, reports, and hung mounts

A wedged FUSE operation cannot be interrupted from Python, so each case runs
under a soft alarm (`--timeout`, default 180s) that reports the case and lets
cleanup run, backed by a hard stop that dumps every thread's stack and exits.
That backstop is the only way to learn *where* a mount hung. A timeout ends the
run: later cases against a wedged mount produce noise, not information.

```console
scripts/fuse-acceptance.sh --live /mnt/testmount \
  --timeout 300 --report-junit results.xml --budget 30
```

`--report-json` also writes every recorded observation, which is what to attach
to a bug report. `--budget SECONDS` flags cases that pass but got slower —
B5 was a 186 ms-per-call regression that a pass/fail suite could not see.
`--list` prints every case and which targets it runs against, and `--fail-fast`
stops at the first failure.

`--journal-check` fails the run if `proton-drive.service` logged any error while
it ran. A suite can pass every assertion while the daemon logs failures behind
it; that has happened, and it was caught only by reading the journal by hand.

With `--live`, abandoned `pdfs-acceptance-*` roots from a crashed run are
removed at startup, but only if they match the exact generated name and are
over an hour old (`PDFS_ACCEPTANCE_REAP_AGE`), so a concurrent run is never
disturbed. An account run instead uses the manifest and reaper described
above.

### Automated mode matrix

An account run drives this matrix itself, in folders it creates. To use
directories of your choice instead, the managed live runner accepts two
existing, empty, unmounted directories. It
registers both as new sync folders, waits for initial synchronization, then
tests all four pairs in order: on-demand/on-demand, on-demand/mirror,
mirror/on-demand, and mirror/mirror. Every transition must become idle, and an
on-demand folder must actually appear as a mount before its contract runs.

```console
mkdir -p /mnt/pdfs-test-a /mnt/pdfs-test-b
scripts/fuse-acceptance.sh --managed-live /mnt/pdfs-test-a /mnt/pdfs-test-b
```

This creates remote folders and permanently deletes those test remotes during
cleanup. It refuses non-empty paths, existing mounts, and paths already present
in `pdfs sync list`. Use `PDFS_ACCEPTANCE_SYNC_TIMEOUT` to extend transition
timeouts and `PDFS_ACCEPTANCE_PDFS` to select a non-installed CLI binary, for
example `target/debug/pdfs`.

After the contract, each mode pair also runs the move cases (`--list` shows
them as `managed`). They move trees between the two folders in both
directions, move several sources in one `pdfs move`, and pass a tree through
My files and out again. Every case waits for Drive before and after the move.
It then checks that the tree is only at the destination, that every byte
arrived, and that neither side made conflict copies. The refusal cases prove
that nothing moves and nothing is lost when:

- the destination already has the name;
- a folder would move into itself;
- a mirror source holds something Drive lacks (a symlink);
- a file in an on-demand source is still open for writing.

The My files case writes a test folder into your real My files and removes it
afterwards. It skips when the daemon reports no My files mount, or when the
locations are on different volumes.

### Durability drill

`--durability` restarts `proton-drive.service` in the middle of the suite and
re-verifies the bytes written before it. `staging/` and `recovery/` can hold the
only copy of a file whose upload has not finished, so this is the case that
proves the queue is persistent rather than in-memory. It is opt-in because it
interrupts a running daemon; `PDFS_ACCEPTANCE_UNIT` selects a different unit.

### Selecting cases

During development, `PDFS_ACCEPTANCE_ONLY` runs tests whose descriptive name
contains the supplied text (for example `PDFS_ACCEPTANCE_ONLY=namespace`). A
release acceptance run must leave it unset so the complete contract executes.

A filter naming a live-only case (every `regression B<n>` is one) selects nothing
in the account-free reference run, which is not an error — that target simply has
nothing to do. Only a filter matching *no case at all* fails, as the typo it is.

Passing more paths runs the same filesystem suite independently against each.
The first path must be the FUSE mount under test; later paths may be another
FUSE mount or a normal local mirror filesystem:

```console
PDFS_ACCEPTANCE_SYNC_TIMEOUT=180 \
  scripts/fuse-acceptance.sh --live /mnt/on-demand-testmount /mnt/testmount
```

If two paths really are views of the **same remote folder**, enable an
additional byte-for-byte convergence check explicitly:

```console
PDFS_ACCEPTANCE_CONVERGENCE=1 \
  scripts/fuse-acceptance.sh --live /mnt/first-view /mnt/second-view
```

Do not enable that flag merely because two sync folders belong to the same
account. Their configured remote UIDs must be identical.

Normally the live suite applies the same API contract independently to each
supplied mount. In convergence mode it exercises the primary once and verifies
that the resulting bytes appear through every secondary view. A pass is
strong evidence for those paths, not a blanket data-loss guarantee. Before a
release, also run the recovery drills in `docs/RECOVERY.md` and inspect
`docs/BUGS.md` for live-verification items.

The runner accepts already-mounted paths instead of starting a daemon. This
keeps authentication and keyring setup explicit and prevents it from silently
reusing or replacing the normal application state directory.