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truenas-truecloud-patch/tests/test_truecloud_nested.py
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flan df412eeff7 test: make three vacuous tests actually test something; drop one duplicate 
The test suite is not bloated -- 3,701 lines of test code against 3,760 lines of
product code, one duplicate pair in 356 tests, 8% single-assertion tests. The waste was
not volume, it was four tests that looked like coverage and provided none:

- test_parents_are_mounted_before_children: the fixture was already in depth order, so
  the sort it exists for was never exercised. Deleting `mounts.sort(key=_depth)` passed
  the whole suite. It now uses datasets whose NAME order differs from their MOUNTPOINT
  depth, which is the only case the sort is for.

- test_it_NEVER_touches_the_current_run: the "current" snapshot was a minute old, so the
  age floor excluded it regardless and the same-snapname guard never ran. That guard
  only matters for a run that OUTLIVES the floor -- which a first full upload easily
  does, and where collecting it would yank the snapshot out from under a backup that is
  still reading from it. Now tested with a 12-hour-old current run.

- the fingerprint/unknown test put the unreadable file in `providers`, which is not
  broken -- so fingerprint() skipped the whole module via is_broken() and the filter
  under test never executed. The blip has to land in the module that IS broken.

- test_the_real_truenas_versions was a byte-identical copy of
  test_async_middleware_is_detected under a name promising more. Replaced with the fact
  actually worth pinning: the flavour probe must read STOCK source, because apply.sh
  re-runs on an already-patched overlay and our own SNAPSHOT_SYNC block is a plain
  `def create_snapshot` -- reading it would report a 25.10 box as synchronous and inject
  the wrong wrapper.

All four now fail when the code they name is broken.
2026-07-14 01:41:25 +00:00

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"""Tests for nested-dataset snapshot staging.
Two rules are under test above all else:
1. A tree that cannot be staged completely must fail LOUDLY. A silently
incomplete backup is the exact failure that stock TrueNAS's "no further
nesting" guard exists to prevent.
2. Every snapshot we cause to exist must be cleaned up. ``zfs.snapshot.delete``
is non-recursive by default and stock calls it with no options, so a
recursive snapshot would otherwise orphan one snapshot per descendant dataset
on EVERY run.
"""
import os
import sys
import time
import pytest
sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "patch"))
import truecloud_nested as tn # noqa: E402
#: Captured at import, BEFORE the autouse fixture patches time.sleep --
#: otherwise the seam check below compares a frozen default against the
#: fixture's own stub and silently matches nothing.
_REAL_SLEEP = time.sleep
from truecloud_nested import ( # noqa: E402
StagingError,
apply_plan,
cleanup_all,
cleanup_task,
current_mounts_under,
delete_snapshot_tree,
plan_staging,
sidecar_for,
snapshot_tree_names,
staging_root_for,
teardown,
verify_staged,
)
@pytest.fixture(autouse=True)
def never_touch_the_real_system(monkeypatch):
"""A unit test must never shell out to the real box. This makes it impossible.
Five tests silently did. `gc_stale_snapshots`'s DEFAULT lister runs
`zfs list -t snapshot -r Tap` -- and on the NAS, `Tap` is the real pool, with
2148 snapshots and a genuine leaked `cloud_backup-5` snapshot in it. Those tests
passed on the dev box only because it has no `zfs` binary (FileNotFoundError,
swallowed by a broad except), and would have gone RED on the one machine the
release process requires them green on -- for reasons having nothing to do with
the code. The same code path calls `umount`.
Tests that need a system command inject one (`runner=` / `list_snapshots=`).
It RECORDS and asserts at teardown rather than raising, because raising would be
swallowed: `gc_stale_snapshots` catches broad `Exception` around its enumeration
(deliberately — it must fail toward collecting nothing). That swallow is exactly
what let five tests shell out unnoticed, so the check must survive it.
"""
attempted = []
def forbidden(cmd):
attempted.append(cmd)
raise AssertionError(f"real system command in a unit test: {cmd!r}")
monkeypatch.setattr(tn, "_run", forbidden)
# ...and the REAL mount table, which is the other half. Nineteen tests were
# reading /proc/self/mounts: harmless here, but on the NAS a name that happened to
# match would send `release_snapdirs`/`teardown` off to run a real `umount`.
#
# Patching the module attribute only works because these are late-bound now. A
# default argument (`mounts_file="/proc/self/mounts"`) is frozen into __defaults__
# at def time and monkeypatching cannot reach it -- which is exactly why the first
# version of this fixture looked like it worked and did not.
monkeypatch.setattr(tn, "MOUNTS_FILE", os.devnull)
# ...and never really sleep. The retry loop waits 5s between attempts for ZFS's
# automount window to expire; a test that hits it burns 20 real seconds and tells
# you nothing. (Same frozen-default trap: `sleep=time.sleep` in the signature could
# not be intercepted at all until it was late-bound.)
slept = []
monkeypatch.setattr(tn.time, "sleep", lambda s: slept.append(s))
yield
assert not attempted, (
"this test ran real system commands: "
+ "; ".join(repr(c) for c in attempted)
+ ". Inject a fake (runner= / list_snapshots=) -- on the NAS these hit the "
"REAL pool, and the suite must not depend on the machine it runs on."
)
SNAP = "cloud_backup-5-20260712030000"
ROOT = "/run/truecloud-nested/cloud_backup-5"
def ds(name, mountpoint, mounted="yes"):
return {
"name": name,
"properties": {
"mountpoint": {"value": mountpoint},
"mounted": {"value": mounted},
},
}
# Mirrors the real layout: apps are datasets, several with their own children.
DATASETS = [
ds("Tap", "/mnt/Tap"),
ds("Tap/apps", "/mnt/Tap/apps"),
ds("Tap/apps/lidarr", "/mnt/Tap/apps/lidarr"),
ds("Tap/apps/lidarr/config", "/mnt/Tap/apps/lidarr/config"),
ds("Tap/apps/immich", "/mnt/Tap/apps/immich"),
ds("Tap/apps/immich/pgdata", "/mnt/Tap/apps/immich/pgdata"),
]
def yes(_path):
return "ok"
def plan(datasets=DATASETS, base_dataset="Tap", base_mp="/mnt/Tap",
path="/mnt/Tap", probe=yes):
return plan_staging(base_dataset, base_mp, path, SNAP, datasets, ROOT, probe=probe)
class TestPlanStaging:
def test_stages_every_descendant_dataset(self):
mounts, skipped = plan()
assert skipped == []
assert len(mounts) == 6 # root + 5 descendants
assert mounts[0] == (f"/mnt/Tap/.zfs/snapshot/{SNAP}", ROOT)
by_target = {t: s for s, t in mounts}
assert by_target[f"{ROOT}/apps"] == f"/mnt/Tap/apps/.zfs/snapshot/{SNAP}"
assert by_target[f"{ROOT}/apps/immich/pgdata"] == (
f"/mnt/Tap/apps/immich/pgdata/.zfs/snapshot/{SNAP}"
)
def test_parents_are_mounted_before_children(self):
# A child's mountpoint dir only exists inside its PARENT's snapshot, so
# mounting a child first fails.
#
# The default fixture is already in depth order, so it never exercised the
# sort at all -- deleting `mounts.sort(key=_depth)` passed the whole suite.
# These datasets are deliberately in the WRONG order by name: `Tap/aaa` is
# three levels deep and `Tap/zzz` is one, so anything that preserves input
# order (or sorts by name) mounts the child first and would fail for real.
awkward = [
ds("Tap", "/mnt/Tap"),
ds("Tap/aaa", "/mnt/Tap/zzz/deep/deeper"),
ds("Tap/zzz", "/mnt/Tap/zzz"),
ds("Tap/mmm", "/mnt/Tap/zzz/deep"),
]
mounts, _ = plan(datasets=awkward)
seen = set()
for _src, target in mounts:
if target != ROOT:
assert os.path.dirname(target) in seen, (
f"{target} is mounted before its parent exists"
)
seen.add(target)
def test_backup_path_below_dataset_root(self):
mounts, _ = plan(base_dataset="Tap/apps", base_mp="/mnt/Tap/apps",
path="/mnt/Tap/apps")
assert mounts[0] == (f"/mnt/Tap/apps/.zfs/snapshot/{SNAP}", ROOT)
targets = [t for _s, t in mounts]
assert f"{ROOT}/lidarr" in targets
assert f"{ROOT}/apps/lidarr" not in targets
def test_base_dataset_is_not_a_descendant_of_itself(self):
mounts, _ = plan(datasets=[ds("Tap", "/mnt/Tap")])
assert len(mounts) == 1
class TestScoping:
def test_unrelated_datasets_are_ignored_silently(self):
# Regression: scoping by mountpoint first dragged in every
# mountpoint-less dataset on the box (all of Tank/.system/*), burying the
# warnings that actually matter.
noisy = DATASETS + [
ds("Tank/.system", "none"),
ds("Tank/.system/cores", "legacy"),
ds("Tank/backups", "/mnt/Tank/backups"),
]
mounts, skipped = plan(datasets=noisy)
assert len(mounts) == 6
assert skipped == [], "datasets outside the base dataset must not be reported"
def test_in_scope_dataset_without_mountpoint_is_reported(self):
datasets = DATASETS + [ds("Tap/apps/weird", "none")]
_mounts, skipped = plan(datasets=datasets)
assert ("Tap/apps/weird", "mountpoint is none") in skipped
def test_unmounted_dataset_is_skipped_but_never_silently(self):
datasets = DATASETS + [ds("Tap/apps/vault", "/mnt/Tap/apps/vault", mounted="no")]
mounts, skipped = plan(datasets=datasets)
assert f"{ROOT}/apps/vault" not in [t for _s, t in mounts]
assert ("Tap/apps/vault", "dataset is not mounted (locked/encrypted?)") in skipped
def test_descendant_mounted_outside_the_path_is_not_an_omission(self):
datasets = DATASETS + [ds("Tap/elsewhere", "/mnt/other")]
mounts, skipped = plan(datasets=datasets)
assert len(mounts) == 6
assert skipped == []
class TestSilentOmissionGuard:
"""The whole point of the feature. These are the tests that matter."""
@staticmethod
def _missing_pgdata(path):
return "missing" if "/mnt/Tap/apps/immich/pgdata/" in path else "ok"
@staticmethod
def _denied_pgdata(path):
if "/mnt/Tap/apps/immich/pgdata/" in path:
return "cannot be read (Permission denied)"
return "ok"
def test_missing_snapshot_on_descendant_raises(self):
with pytest.raises(StagingError, match="incomplete tree"):
plan(probe=self._missing_pgdata)
def test_error_names_the_offending_dataset(self):
with pytest.raises(StagingError, match="Tap/apps/immich/pgdata"):
plan(probe=self._missing_pgdata)
def test_missing_and_unreadable_are_reported_differently(self):
# os.path.isdir() collapses both into False, which would report a
# permission problem as "has no snapshot" and send you hunting for a
# snapshot that is sitting right there. Both abort -- but say which.
with pytest.raises(StagingError, match="has no snapshot"):
plan(probe=self._missing_pgdata)
with pytest.raises(StagingError, match="Permission denied"):
plan(probe=self._denied_pgdata)
class TestSnapshotTreeNames:
"""zfs.snapshot.delete is non-recursive; we must sweep children ourselves."""
ALL = [
"Tap@cloud_backup-5-20260712030000",
"Tap/apps@cloud_backup-5-20260712030000",
"Tap/apps/lidarr/config@cloud_backup-5-20260712030000",
"Tap@auto-2026-07-12_03-00", # unrelated periodic snapshot
"Tap/apps@cloud_backup-9-20260712030000", # another task
"Tank/backups@cloud_backup-5-20260712030000", # different pool
]
def test_returns_parent_and_all_children(self):
got = snapshot_tree_names("Tap@cloud_backup-5-20260712030000", self.ALL)
assert set(got) == {
"Tap@cloud_backup-5-20260712030000",
"Tap/apps@cloud_backup-5-20260712030000",
"Tap/apps/lidarr/config@cloud_backup-5-20260712030000",
}
def test_never_touches_periodic_or_other_tasks_or_other_pools(self):
got = snapshot_tree_names("Tap@cloud_backup-5-20260712030000", self.ALL)
assert "Tap@auto-2026-07-12_03-00" not in got
assert "Tap/apps@cloud_backup-9-20260712030000" not in got
assert "Tank/backups@cloud_backup-5-20260712030000" not in got
def test_malformed_snapshot_name_yields_nothing(self):
assert snapshot_tree_names("Tap", self.ALL) == []
class _FrameworkCRUDService:
"""Stands in for middlewared's real `CRUDService` base class.
This shape is load-bearing, and a fake without it is worse than no fake at all.
The real CRUDService defines `delete` on the BASE class and dispatches to
`self.do_delete` at call time, so a bound `delete` exists on EVERY subclass —
including one whose `do_delete` iX has deleted. A fake that is just a bare object
with a `delete` attribute cannot express that, so a runtime check that asks
`hasattr(service, "delete")` would look CORRECT against the fake while being
useless against the real thing. That is exactly what happened: the first version
of this fix passed its test and did nothing on a real box.
`__module__` is set to middlewared's real framework package because that is how
`_defines_delete` tells plumbing apart from an implementation.
"""
def delete(self, *args, **kwargs): # the generic dispatcher -> self.do_delete
raise NotImplementedError
_FrameworkCRUDService.__module__ = "middlewared.service.crud_service"
class _FakeSnapshotService(_FrameworkCRUDService):
"""What `middleware.get_service("<ns>")` hands back: a plugin CRUDService.
`delete_method=None` models the dangerous case — iX guts the concrete method but
leaves the service registered (they have already done this to
`pool.snapshot.do_update` on master). The inherited `delete` is still there and
still callable; only the implementation is gone.
"""
def __init__(self, delete_method):
if delete_method:
# Define it on the CLASS, not the instance: `_defines_delete` walks the
# MRO's __dict__s, exactly as it must against a real service.
cls = type(
"FakePluginSnapshotService", (_FrameworkCRUDService,),
{delete_method: lambda self, *a, **kw: None},
)
cls.__module__ = "middlewared.plugins.pool_.snapshot"
self.__class__ = cls
class FakeMiddleware:
"""middlewared as this module actually uses it: `call_sync`, from a thread.
The module is synchronous on purpose -- see the orchestration note in
truecloud_nested.py. TrueNAS <= 25.10 reaches it through
`await middleware.run_in_thread(...)` and TrueNAS 26 calls it directly, but the
logic below the boundary is the same code either way, so it is tested once.
`snapshot_ns` picks which middleware GENERATION this is, because they do not
agree on what the snapshot service is called:
pool.snapshot 25.10 and 26 (26 has ONLY this -- plugins/zfs_/ is gone)
zfs.snapshot 24.10 and 25.04 (pool.snapshot does not exist yet)
A method in the namespace this box does NOT have raises, exactly as middleware
does ("Method does not exist"). That is what makes the runtime picker testable:
a module that guessed wrong would blow up here instead of silently orphaning
snapshots on somebody's NAS.
"""
def __init__(self, snapshots=None, snapshot_ns="pool.snapshot",
delete_method="delete"):
self.snapshots = list(snapshots or [])
self.calls = []
self.logger = None
self.snapshot_ns = snapshot_ns
#: A CRUDService exposes `delete` from a method NAMED `do_delete`. Both
#: spellings are live across the matrix, and the runtime must accept either
#: -- it resolves the namespace by asking whether it can DELETE, not merely
#: whether the service is registered.
self.delete_method = delete_method
def get_service(self, name):
if name != self.snapshot_ns:
raise KeyError(name) # middleware raises KeyError for an unknown ns
return _FakeSnapshotService(self.delete_method)
def list_snapshots(self, dataset):
"""Stands in for `zfs list -t snapshot -r <dataset>`.
Enumeration comes from ZFS now, NOT from middleware -- middleware's query
hides internal datasets, and a sweep that cannot see a snapshot can never
collect it. Passed in as `list_snapshots=` so the seam is explicit.
"""
return [
n for n in self.snapshots
if n.split("@")[0] == dataset or n.startswith(dataset + "/")
]
def call_sync(self, method, *args):
self.calls.append((method, args))
namespace, _, op = method.rpartition(".")
if namespace != self.snapshot_ns:
raise RuntimeError("Method does not exist")
if op == "query":
return [{"name": n} for n in self.snapshots]
if op == "delete":
name = args[0]
opts = args[1] if len(args) > 1 else {}
if name not in self.snapshots:
raise RuntimeError("does not exist")
if opts.get("recursive"):
# Real `zfs destroy -r` takes the parent and every child snapshot.
for n in snapshot_tree_names(name, list(self.snapshots)):
self.snapshots.remove(n)
else:
self.snapshots.remove(name)
return True
raise AssertionError(f"unexpected call {method}")
def stub_core(monkeypatch, tn, *, plan=None, order=None, plan_raises=None):
"""Replace the blocking core (plan/apply/verify/teardown) with recorders.
stage_nested calls these directly now, so they are patched by NAME rather than
intercepted at a `run_in_thread` boundary that no longer exists.
"""
def record(name, result):
def fn(*args, **kwargs):
if order is not None:
order.append(name)
if name == "plan_staging" and plan_raises is not None:
raise plan_raises
return result() if callable(result) else result
fn.__name__ = name
return fn
real_write = tn._write_sidecar
def write_sidecar(*args, **kwargs):
if order is not None:
order.append("_write_sidecar")
return real_write(*args, **kwargs)
monkeypatch.setattr(tn, "_write_sidecar", write_sidecar)
monkeypatch.setattr(tn, "plan_staging", record("plan_staging", plan or ([], [])))
monkeypatch.setattr(tn, "apply_plan", record("apply_plan", True))
monkeypatch.setattr(tn, "verify_staged", record("verify_staged", True))
monkeypatch.setattr(tn, "teardown", record("teardown", []))
class TestDeleteSnapshotTree:
def test_deletes_parent_and_every_child(self):
mw = FakeMiddleware([
"Tap@snap", "Tap/apps@snap", "Tap/apps/lidarr@snap", "Tap@keepme",
])
delete_snapshot_tree(mw, "Tap@snap", list_snapshots=mw.list_snapshots)
assert mw.snapshots == ["Tap@keepme"]
def test_is_idempotent_when_stock_already_removed_the_parent(self):
# Stock's finally can win the race once our mounts are released.
mw = FakeMiddleware(["Tap/apps@snap", "Tap/apps/lidarr@snap"])
delete_snapshot_tree(mw, "Tap@snap", list_snapshots=mw.list_snapshots)
assert mw.snapshots == []
def test_uses_a_single_recursive_delete_not_252_individual_ones(self):
# 252 sequential deletes are slow AND not atomic: a run killed part-way
# through leaves exactly the orphans this function exists to prevent.
mw = FakeMiddleware(["Tap@snap", "Tap/apps@snap", "Tap/apps/lidarr@snap"])
listed = []
def counting_lister(dataset):
listed.append(dataset)
return mw.list_snapshots(dataset)
delete_snapshot_tree(mw, "Tap@snap", list_snapshots=counting_lister)
assert mw.snapshots == []
deletes = [a for m, a in mw.calls if m.endswith(".delete")]
assert len(deletes) == 1, "should be ONE recursive call, not one per snapshot"
assert deletes[0][1] == {"recursive": True}
assert listed == ["Tap"], (
"the fast path must enumerate EXACTLY ONCE -- to CONFIRM the tree is gone. "
"Zero would mean trusting a delete that returned without raising, and a "
"silent no-op delete then makes cleanup_task drop the sidecar and orphan "
"~250 snapshots forever. More than once is waste."
)
def test_survives_recursive_and_enumeration_failure_by_deleting_the_parent(self):
# Both the recursive delete AND the ZFS enumeration fail. The sweep must still
# remove the parent rather than give up entirely.
class NoRecursive(FakeMiddleware):
def call_sync(self, method, *args):
if method.endswith(".delete") and len(args) > 1:
raise RuntimeError("recursive delete unavailable")
return super().call_sync(method, *args)
def broken_lister(_dataset):
raise tn.ZfsError("boom")
mw = NoRecursive(["Tap@snap"])
delete_snapshot_tree(mw, "Tap@snap", list_snapshots=broken_lister)
assert mw.snapshots == [], "must fall back to at least deleting the parent"
def test_leaves_unrelated_snapshots_alone_when_the_tree_is_gone(self):
mw = FakeMiddleware(["Tap@unrelated"])
delete_snapshot_tree(mw, "Tap@snap", list_snapshots=mw.list_snapshots)
assert mw.snapshots == ["Tap@unrelated"]
class TestStageNestedOrdering:
def test_sidecar_is_written_before_anything_is_mounted(self, tmp_path, monkeypatch):
# middlewared can die at any moment. If the snapshot were recorded only
# after apply_plan, a crash in that window would orphan a 160-snapshot
# tree -- the precise failure the sidecar exists to prevent.
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
order = []
stub_core(monkeypatch, tn, order=order,
plan=([("/src", str(tmp_path / "cloud_backup-5"))], []))
_mw = FakeMiddleware()
tn.stage_nested(
_mw, "/mnt/Tap", "Tap@snap", "Tap", "/mnt/Tap",
"cloud_backup-5", DATASETS, list_snapshots=_mw.list_snapshots,
)
assert order.index("_write_sidecar") < order.index("apply_plan")
def test_reclaims_the_snapshot_tree_left_by_a_crashed_run(self, tmp_path,
monkeypatch):
# teardown() reclaims the crashed run's MOUNTS, but nothing else would
# ever reclaim its SNAPSHOTS -- and we are about to overwrite the only
# record of them. One crash would orphan 160+ snapshots permanently.
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5")
os.makedirs(os.path.dirname(root), exist_ok=True)
with open(sidecar_for(root), "w", encoding="utf-8") as fh:
fh.write("Tap@old-crashed-run")
mw = FakeMiddleware(["Tap@old-crashed-run", "Tap/apps@old-crashed-run"])
stub_core(monkeypatch, tn, plan=([("/src", root)], []))
tn.stage_nested(
mw, "/mnt/Tap", "Tap@new", "Tap", "/mnt/Tap",
"cloud_backup-5", DATASETS, list_snapshots=mw.list_snapshots,
)
assert mw.snapshots == [], "the crashed run's snapshot tree must be reclaimed"
def test_sidecar_is_KEPT_when_staging_fails(self, tmp_path, monkeypatch):
# The caller sweeps the snapshot tree on the way out, and anything still busy
# SURVIVES that sweep -- with the sidecar as its only record. Removing the
# sidecar here would orphan those snapshots permanently.
#
# The asymmetry is the point: a sidecar left behind when the tree is already
# gone costs one no-op delete on the next run; a sidecar removed while the tree
# still exists is unrecoverable.
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5")
stub_core(monkeypatch, tn, plan_raises=StagingError("boom"))
with pytest.raises(StagingError):
_mw = FakeMiddleware()
tn.stage_nested(
_mw, "/mnt/Tap", "Tap@snap", "Tap", "/mnt/Tap",
"cloud_backup-5", DATASETS, list_snapshots=_mw.list_snapshots,
)
assert os.path.exists(sidecar_for(root)), (
"sidecar removed on staging failure — any snapshot the caller's sweep "
"cannot delete is now orphaned forever"
)
with open(sidecar_for(root), encoding="utf-8") as fh:
assert fh.read().strip() == "Tap@snap"
class TestCleanupTask:
def test_recovers_snapshot_from_sidecar_after_middlewared_restart(self, tmp_path,
monkeypatch):
# The sidecar is the ONLY record of the pinned snapshot, precisely so a
# middlewared restart cannot orphan the tree.
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5", base=str(tmp_path))
os.makedirs(root, exist_ok=True)
with open(sidecar_for(root), "w", encoding="utf-8") as fh:
fh.write("Tap@snap")
mw = FakeMiddleware(["Tap@snap", "Tap/apps@snap"])
monkeypatch.setattr(tn, "teardown", lambda *_a, **_k: [])
cleanup_task(mw, "cloud_backup-5", list_snapshots=mw.list_snapshots)
assert mw.snapshots == []
assert not os.path.exists(sidecar_for(root))
def test_is_a_noop_when_never_staged(self, tmp_path, monkeypatch):
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path / "nope"))
mw = FakeMiddleware(["Tap@snap"])
cleanup_task(mw, "cloud_backup-5", list_snapshots=mw.list_snapshots)
assert mw.calls == []
assert mw.snapshots == ["Tap@snap"]
class TestVerifyStaged:
"""Anti-regression guard: proves the staged tree is real before we back it up."""
def test_passes_when_every_target_is_mounted_and_root_non_empty(self):
mounts = [("/src", ROOT), ("/src/a", f"{ROOT}/a")]
assert verify_staged(mounts, ismount=lambda p: True, listdir=lambda p: ["apps"])
def test_raises_when_a_target_is_not_actually_mounted(self):
# This is the case that would produce a silently-empty backup.
mounts = [("/src", ROOT), ("/src/a", f"{ROOT}/a")]
with pytest.raises(StagingError, match="not a mountpoint"):
verify_staged(mounts, ismount=lambda p: p == ROOT, listdir=lambda p: ["apps"])
def test_raises_when_staging_root_is_empty(self):
with pytest.raises(StagingError, match="empty"):
verify_staged([("/src", ROOT)], ismount=lambda p: True, listdir=lambda p: [])
def test_raises_on_empty_plan(self):
with pytest.raises(StagingError):
verify_staged([])
class FakeRunner:
def __init__(self, fail_on=None):
self.fail_on = fail_on
self.calls = []
def __call__(self, cmd):
self.calls.append(cmd)
class R:
returncode = 0
stderr = ""
if self.fail_on and cmd[0] == "mount" and cmd[2] == self.fail_on:
R.returncode = 32
R.stderr = "mount failed"
return R
class TestApplyPlanRollback:
def test_rolls_back_mounts_when_one_fails(self, tmp_path):
# A half-built tree must never reach the backup tool.
root = str(tmp_path / "root")
mounts = [("/src", root), ("/src/a", root + "/a"), ("/src/b", root + "/b")]
runner = FakeRunner(fail_on="/src/b")
with pytest.raises(StagingError, match="bind-mount"):
apply_plan(mounts, runner=runner, isdir=lambda _p: True)
umounts = [c[-1] for c in runner.calls if c[0] == "umount"]
assert umounts == [root + "/a", root]
def test_raises_when_target_missing(self, tmp_path):
root = str(tmp_path / "root")
with pytest.raises(StagingError, match="does not exist"):
apply_plan(
[("/src", root), ("/src/a", root + "/a")],
runner=FakeRunner(),
isdir=lambda p: p == root,
)
class TestTeardown:
def test_unmounts_deepest_first(self, tmp_path):
mounts_file = tmp_path / "mounts"
mounts_file.write_text(
f"tmpfs {ROOT} tmpfs rw 0 0\n"
f"tmpfs {ROOT}/apps tmpfs rw 0 0\n"
f"tmpfs {ROOT}/apps/lidarr/config tmpfs rw 0 0\n"
f"tmpfs {ROOT}/apps/lidarr tmpfs rw 0 0\n"
"tmpfs /somewhere/else tmpfs rw 0 0\n"
)
runner = FakeRunner()
teardown(ROOT, runner=runner, mounts_file=str(mounts_file))
order = [c[-1] for c in runner.calls if c[0] == "umount"]
assert order == [
f"{ROOT}/apps/lidarr/config",
f"{ROOT}/apps/lidarr",
f"{ROOT}/apps",
ROOT,
]
assert "/somewhere/else" not in order
def test_is_idempotent_when_nothing_mounted(self, tmp_path):
mounts_file = tmp_path / "mounts"
mounts_file.write_text("tmpfs /somewhere/else tmpfs rw 0 0\n")
runner = FakeRunner()
assert teardown(ROOT, runner=runner, mounts_file=str(mounts_file)) == []
assert runner.calls == []
def test_falls_back_to_lazy_umount(self, tmp_path):
mounts_file = tmp_path / "mounts"
mounts_file.write_text(f"tmpfs {ROOT} tmpfs rw 0 0\n")
class Busy(FakeRunner):
def __call__(self, cmd):
self.calls.append(cmd)
class R:
returncode = 0 if "-l" in cmd else 32
stderr = "target is busy"
return R
runner = Busy()
assert teardown(ROOT, runner=runner, mounts_file=str(mounts_file)) == []
assert ["umount", "-l", ROOT] in runner.calls
class TestCleanupAll:
"""uninstall.sh and recover.sh call this instead of reimplementing teardown."""
def test_reports_orphan_snapshots_before_deleting_their_sidecars(self, tmp_path):
# The sidecar is the only record that an interrupted run's snapshot tree
# is still on disk. Deleting it without naming the snapshot orphans the
# whole tree silently.
base = tmp_path / "stage"
base.mkdir()
(base / "cloud_backup-5.snapshot").write_text("Tap@interrupted")
mounts_file = tmp_path / "mounts"
mounts_file.write_text("")
lines, errors = cleanup_all(
base=str(base), runner=FakeRunner(), mounts_file=str(mounts_file)
)
assert errors == []
assert any("Tap@interrupted" in ln for ln in lines)
assert any("zfs destroy -r" in ln for ln in lines)
# Sidecar cleared only after being reported.
assert not (base / "cloud_backup-5.snapshot").exists()
def test_unmounts_everything_under_the_base_deepest_first(self, tmp_path):
base = tmp_path / "stage"
base.mkdir()
mounts_file = tmp_path / "mounts"
mounts_file.write_text(
f"tmpfs {base} tmpfs rw 0 0\n"
f"tmpfs {base}/cloud_backup-5 tmpfs rw 0 0\n"
f"tmpfs {base}/cloud_backup-5/apps tmpfs rw 0 0\n"
)
runner = FakeRunner()
_lines, errors = cleanup_all(
base=str(base), runner=runner, mounts_file=str(mounts_file)
)
assert errors == []
order = [c[-1] for c in runner.calls if c[0] == "umount"]
assert order == [
f"{base}/cloud_backup-5/apps",
f"{base}/cloud_backup-5",
str(base),
]
def test_keeps_sidecars_when_an_unmount_failed(self, tmp_path):
# If a mount is stuck, the snapshot is still pinned — so the record of it
# must survive for the next run (or the operator) to act on.
base = tmp_path / "stage"
base.mkdir()
(base / "cloud_backup-5.snapshot").write_text("Tap@stuck")
mounts_file = tmp_path / "mounts"
mounts_file.write_text(f"tmpfs {base}/cloud_backup-5 tmpfs rw 0 0\n")
class Stuck(FakeRunner):
def __call__(self, cmd):
self.calls.append(cmd)
class R:
returncode = 32
stderr = "target is busy"
return R
_lines, errors = cleanup_all(
base=str(base), runner=Stuck(), mounts_file=str(mounts_file)
)
assert errors, "a stuck unmount must be reported"
assert (base / "cloud_backup-5.snapshot").exists()
def test_is_a_noop_on_a_clean_system(self, tmp_path):
mounts_file = tmp_path / "mounts"
mounts_file.write_text("")
lines, errors = cleanup_all(
base=str(tmp_path / "absent"), runner=FakeRunner(),
mounts_file=str(mounts_file),
)
assert errors == []
assert lines == [" None active."]
class TestCurrentMountsUnder:
def test_matches_only_the_staging_subtree(self, tmp_path):
mounts_file = tmp_path / "mounts"
# "cloud_backup-50" must NOT match "cloud_backup-5".
mounts_file.write_text(
f"tmpfs {ROOT} tmpfs rw 0 0\n"
"tmpfs /run/truecloud-nested/cloud_backup-50 tmpfs rw 0 0\n"
)
assert current_mounts_under(ROOT, mounts_file=str(mounts_file)) == [ROOT]
class TestStagingRootFor:
def test_stable_per_task(self):
assert staging_root_for("cloud_backup-5") == "/run/truecloud-nested/cloud_backup-5"
def test_sanitises_path_separators(self):
assert "/" not in staging_root_for("evil/name").rsplit("/", 1)[-1]
@pytest.mark.parametrize("name", ["..", ".", "...", "/", ""])
def test_dot_components_cannot_escape_the_staging_base(self, name):
# os.path.join(BASE, "..") normalises to /run — teardown would rmdir it.
root = staging_root_for(name)
assert os.path.normpath(root).startswith("/run/truecloud-nested/")
class TestZfsAutomountKeepsSnapshotsBusy:
""""dataset is busy" is EXPECTED, TRANSIENT, and used to orphan snapshots forever.
Reading `<dataset>/.zfs/snapshot/<snap>/` makes ZFS **automount** that snapshot,
and it stays mounted for zfs_expire_snapshot seconds (300 by default) after the
last access. teardown() unmounts OUR bind mounts, but not the automount underneath
-- so `zfs destroy` refuses with EBUSY for everything restic read recently.
Observed on a real 256-snapshot tree: 253 swept cleanly, and the 3 datasets restic
had touched last failed with "dataset is busy". cleanup_task then removed the
sidecar anyway, so nothing would ever reclaim them. A few snapshots leaked per run,
forever.
"""
MOUNTS = (
"tmpfs /run tmpfs rw 0 0\n"
"Tap/apps/prometheus /mnt/Tap/apps/prometheus/.zfs/snapshot/snap1 zfs ro 0 0\n"
"Tap/apps/standing/data /mnt/Tap/apps/standing/data/.zfs/snapshot/snap1 zfs ro 0 0\n"
"Tap /mnt/Tap/.zfs/snapshot/snap1 zfs ro 0 0\n"
"Tap/other /mnt/Tap/other/.zfs/snapshot/OTHER zfs ro 0 0\n"
)
def _mounts_file(self, tmp_path):
p = tmp_path / "mounts"
p.write_text(self.MOUNTS)
return str(p)
def test_it_finds_the_automounts_for_this_snapshot_only(self, tmp_path):
import truecloud_nested as tn
found = tn.snapdir_automounts("snap1", mounts_file=self._mounts_file(tmp_path))
assert "/mnt/Tap/other/.zfs/snapshot/OTHER" not in found
assert len(found) == 3
def test_deepest_first(self, tmp_path):
# A child's automount must be released before its parent's.
import truecloud_nested as tn
found = tn.snapdir_automounts("snap1", mounts_file=self._mounts_file(tmp_path))
assert found[-1] == "/mnt/Tap/.zfs/snapshot/snap1"
def test_release_snapdirs_unmounts_them(self, tmp_path):
import truecloud_nested as tn
called = []
class R:
returncode = 0
stderr = ""
def runner(cmd):
called.append(cmd)
return R()
errs = tn.release_snapdirs("snap1", runner=runner,
mounts_file=self._mounts_file(tmp_path))
assert errs == []
assert all(c[0] == "umount" for c in called)
assert len(called) == 3
class BusyMiddleware(FakeMiddleware):
"""Deletes fail with EBUSY until `busy_until_attempt` passes -- like a ZFS
automount expiring."""
def __init__(self, snapshots, busy, busy_for=2):
super().__init__(snapshots)
self.busy = set(busy)
self.busy_for = busy_for
self.attempts = 0
def call_sync(self, method, *args):
if method.endswith(".delete"):
name = args[0]
opts = args[1] if len(args) > 1 else {}
if opts.get("recursive"):
raise RuntimeError("cannot destroy snapshot: dataset is busy")
if name in self.busy:
self.attempts += 1
if self.attempts <= self.busy_for * len(self.busy):
raise RuntimeError(f"cannot destroy '{name}': dataset is busy")
return super().call_sync(method, *args)
class TestDeleteRetriesAndReportsSurvivors:
def test_a_transient_busy_is_retried_and_wins(self, monkeypatch):
import truecloud_nested as tn
monkeypatch.setattr(tn, "release_snapdirs", lambda *a, **k: [])
mw = BusyMiddleware(
["Tap@snap", "Tap/apps@snap", "Tap/apps/prometheus@snap"],
busy=["Tap/apps/prometheus@snap"], busy_for=1,
)
survivors = tn.delete_snapshot_tree(mw, "Tap@snap", sleep=lambda _s: None, list_snapshots=mw.list_snapshots)
assert survivors == []
assert mw.snapshots == []
def test_a_permanently_busy_snapshot_is_REPORTED_not_swallowed(self, monkeypatch):
import truecloud_nested as tn
monkeypatch.setattr(tn, "release_snapdirs", lambda *a, **k: [])
mw = BusyMiddleware(
["Tap@snap", "Tap/apps/prometheus@snap"],
busy=["Tap/apps/prometheus@snap"], busy_for=99,
)
survivors = tn.delete_snapshot_tree(mw, "Tap@snap", sleep=lambda _s: None, list_snapshots=mw.list_snapshots)
assert survivors == ["Tap/apps/prometheus@snap"]
assert mw.snapshots == ["Tap/apps/prometheus@snap"]
def test_the_automounts_are_released_before_deleting(self, monkeypatch):
import truecloud_nested as tn
order = []
monkeypatch.setattr(tn, "release_snapdirs",
lambda name, **k: order.append(("release", name)) or [])
mw = FakeMiddleware(["Tap@snap"])
real = mw.call_sync
def spy(method, *args):
order.append((method, args[0] if args else None))
return real(method, *args)
mw.call_sync = spy
tn.delete_snapshot_tree(mw, "Tap@snap", sleep=lambda _s: None, list_snapshots=mw.list_snapshots)
assert order[0] == ("release", "snap"), order
class TestSidecarSurvivesAnIncompleteSweep:
def test_the_sidecar_is_KEPT_when_snapshots_could_not_be_deleted(
self, tmp_path, monkeypatch
):
# It is the ONLY record those snapshots exist. Removing it orphans them
# permanently -- which is exactly what happened on the real box.
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
monkeypatch.setattr(tn, "release_snapdirs", lambda *a, **k: [])
root = tn.staging_root_for("cloud_backup-5")
os.makedirs(root, exist_ok=True)
with open(sidecar_for(root), "w", encoding="utf-8") as fh:
fh.write("Tap@snap")
mw = BusyMiddleware(["Tap@snap", "Tap/apps/prometheus@snap"],
busy=["Tap/apps/prometheus@snap"], busy_for=99)
monkeypatch.setattr(tn, "delete_snapshot_tree",
lambda m, s, logger=None, **kw: ["Tap/apps/prometheus@snap"])
tn.cleanup_task(mw, "cloud_backup-5", list_snapshots=mw.list_snapshots)
assert os.path.exists(sidecar_for(root)), (
"sidecar removed despite survivors — they are now orphaned forever"
)
def test_the_sidecar_is_removed_on_a_clean_sweep(self, tmp_path, monkeypatch):
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5")
os.makedirs(root, exist_ok=True)
with open(sidecar_for(root), "w", encoding="utf-8") as fh:
fh.write("Tap@snap")
monkeypatch.setattr(tn, "delete_snapshot_tree", lambda m, s, logger=None, **kw: [])
_mw = FakeMiddleware()
tn.cleanup_task(_mw, "cloud_backup-5", list_snapshots=_mw.list_snapshots)
assert not os.path.exists(sidecar_for(root))
class TestTheSidecarCarriesEveryPendingTree:
"""The sidecar holds a LIST, and that is a bug fix, not a generalisation.
It used to hold ONE snapshot. So a run that reclaimed an older tree, FAILED to
finish reclaiming it, and then recorded its own snapshot would **overwrite the only
record of the survivor** — orphaning it permanently, via the exact code written to
prevent orphans.
Observed live: a snapshot survived one run; the next run's reclaim also failed
(ZFS's 300s automount window had not elapsed, because the two runs were minutes
apart); the record was overwritten; the snapshot was orphaned for good.
"""
def test_round_trips_a_list(self, tmp_path):
import truecloud_nested as tn
root = str(tmp_path / "cloud_backup-5")
tn._write_sidecar(root, ["Tap@a", "Tap@b"])
assert tn._read_sidecar(root) == ["Tap@a", "Tap@b"]
def test_reads_the_old_single_line_format(self, tmp_path):
# Boxes upgrading from an older version have a one-line sidecar on disk.
import truecloud_nested as tn
root = str(tmp_path / "cloud_backup-5")
os.makedirs(os.path.dirname(sidecar_for(root)), exist_ok=True)
with open(sidecar_for(root), "w", encoding="utf-8") as fh:
fh.write("Tap@legacy")
assert tn._read_sidecar(root) == ["Tap@legacy"]
def test_a_failed_reclaim_is_carried_forward_not_overwritten(
self, tmp_path, monkeypatch
):
# THE bug. stage_nested reclaims an old tree, cannot finish, then records its
# own snapshot -- the survivor must still be in the sidecar afterwards.
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5")
os.makedirs(os.path.dirname(root), exist_ok=True)
tn._write_sidecar(root, ["Tap@old"])
# The reclaim of Tap@old leaves one snapshot behind (still busy).
monkeypatch.setattr(
tn, "delete_snapshot_tree",
lambda m, s, logger=None, **kw: ["Tap/apps/x@old"] if s == "Tap@old" else [],
)
stub_core(monkeypatch, tn, plan=([("/src", root)], []))
_mw = FakeMiddleware()
tn.stage_nested(_mw, "/mnt/Tap", "Tap@new", "Tap", "/mnt/Tap",
"cloud_backup-5", DATASETS,
list_snapshots=_mw.list_snapshots)
recorded = tn._read_sidecar(root)
assert "Tap/apps/x@old" in recorded, (
"the failed reclaim's survivor was dropped — orphaned forever"
)
assert "Tap@new" in recorded, "our own snapshot must also be recorded"
def test_cleanup_sweeps_every_pending_tree_and_records_only_survivors(
self, tmp_path, monkeypatch
):
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5")
os.makedirs(root, exist_ok=True)
tn._write_sidecar(root, ["Tap@old", "Tap@new"])
swept = []
def fake_delete(m, s, logger=None, **kw):
swept.append(s)
return ["Tap/apps/x@new"] if s == "Tap@new" else []
monkeypatch.setattr(tn, "delete_snapshot_tree", fake_delete)
_mw = FakeMiddleware()
tn.cleanup_task(_mw, "cloud_backup-5", list_snapshots=_mw.list_snapshots)
assert swept == ["Tap@old", "Tap@new"], "both pending trees must be swept"
# Only the SURVIVOR is written back -- re-recording Tap@old would make every
# future run re-sweep a tree that is already gone.
assert tn._read_sidecar(root) == ["Tap/apps/x@new"]
def test_a_fully_clean_sweep_removes_the_sidecar(self, tmp_path, monkeypatch):
import truecloud_nested as tn
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
root = tn.staging_root_for("cloud_backup-5")
os.makedirs(root, exist_ok=True)
tn._write_sidecar(root, ["Tap@a", "Tap@b"])
monkeypatch.setattr(tn, "delete_snapshot_tree", lambda m, s, logger=None, **kw: [])
_mw = FakeMiddleware()
tn.cleanup_task(_mw, "cloud_backup-5", list_snapshots=_mw.list_snapshots)
assert not os.path.exists(sidecar_for(root))
def test_cleanup_all_reports_each_pending_snapshot_on_its_own_line(self, tmp_path):
# It formats them for a human during uninstall. A list rendered into an
# f-string would print "['Tap@a', 'Tap@b']" at them.
import truecloud_nested as tn
root = str(tmp_path / "cloud_backup-5")
tn._write_sidecar(root, ["Tap@a", "Tap@b"])
lines, _errors = tn.cleanup_all(
base=str(tmp_path),
glob_fn=lambda _p: [sidecar_for(root)],
mounts_file=os.devnull,
)
notes = [ln for ln in lines if "left snapshot" in ln]
assert len(notes) == 2
assert "'Tap@a'" in notes[0] and "'Tap@b'" in notes[1]
assert "[" not in "".join(notes)
class TestGarbageCollectorSelection:
"""`stale_snapshot_names` DELETES DATA on a name match.
A name match is a weaker claim than a recorded fact, so every way it could be wrong
is a test. It exists because the sidecar — which IS a recorded fact — lives in /run,
which is tmpfs: a reboot mid-backup destroys it and orphans a 250-snapshot tree with
nothing left pointing at it. This is the only thing that would ever find those.
"""
import datetime as _dt
NOW = _dt.datetime(2026, 7, 14, 12, 0, 0, tzinfo=_dt.UTC)
CURRENT = "Tap@cloud_backup-5-20260714115900" # 1 minute ago
OLD = "Tap/apps/x@cloud_backup-5-20260713030000" # ~33 hours ago
def collect(self, names, **kw):
import truecloud_nested as tn
return tn.stale_snapshot_names(
"cloud_backup-5", self.CURRENT, names, self.NOW, **kw
)
def test_it_collects_our_own_leftovers(self):
assert self.collect([self.OLD]) == [self.OLD]
def test_it_NEVER_touches_the_current_run(self):
# Both the parent and its children share the current snapname.
names = [self.CURRENT, "Tap/apps/x@cloud_backup-5-20260714115900"]
assert self.collect(names) == []
def test_it_NEVER_touches_the_current_run_EVEN_WHEN_IT_IS_OLD(self):
# The one that matters, and the one that was not tested: a backup running
# longer than the age floor. The old test's `current` was a minute old, so the
# floor excluded it anyway and the same-snapname guard never ran -- deleting
# that guard passed the whole suite.
#
# A first full upload of a 100 GB pool takes hours. If the GC collected the
# snapshot of the run that is CURRENTLY READING FROM IT, restic would be
# yanked out from under itself mid-backup.
import datetime as dt
old_current = "Tap@cloud_backup-5-20260714000000" # 12 hours old
names = [old_current, "Tap/apps/x@cloud_backup-5-20260714000000"]
assert tn.stale_snapshot_names(
"cloud_backup-5", old_current, names,
dt.datetime(2026, 7, 14, 12, 0, 0, tzinfo=dt.UTC),
) == [], (
"the GC collected the snapshot of the run that is using it. A long first "
"upload would be destroyed mid-flight."
)
def test_it_NEVER_touches_a_periodic_snapshot(self):
assert self.collect(["Tap/apps/x@auto-2026-07-13_03-00"]) == []
def test_it_NEVER_touches_a_human_made_snapshot(self):
assert self.collect(["Tap@before-i-broke-everything"]) == []
def test_it_NEVER_touches_another_TASK(self):
# cloud_backup-5 must not match cloud_backup-50. This is why the prefix
# carries the trailing dash.
assert self.collect(["Tap/apps/x@cloud_backup-50-20260713030000"]) == []
assert self.collect(["Tap/apps/x@cloud_backup-7-20260713030000"]) == []
def test_it_NEVER_touches_a_one_time_backup(self):
assert self.collect(["Tap@cloud_backup-onetime-20260713030000"]) == []
def test_it_NEVER_touches_a_snapshot_that_is_MOUNTED(self):
# An in-flight run pins its own snapshots. This — not the age heuristic — is
# what actually protects a concurrent backup.
assert self.collect([self.OLD], in_use={self.OLD}) == []
def test_it_NEVER_touches_a_snapshot_younger_than_the_minimum_age(self):
# Covers the seconds-long window between `zfs snapshot -r` and the mounts
# appearing, when a live run's snapshots look exactly like garbage.
young = "Tap/apps/x@cloud_backup-5-20260714113000" # 30 minutes ago
assert self.collect([young]) == []
assert self.collect([young], min_age=60) == [young]
def test_a_name_it_cannot_parse_is_left_alone(self):
assert self.collect(["Tap@cloud_backup-5-not-a-timestamp"]) == []
assert self.collect(["Tap@cloud_backup-5-"]) == []
def test_a_realistic_mixed_pool(self):
names = [
self.CURRENT, # ours, running
"Tap/apps/x@cloud_backup-5-20260714115900", # ours, running (child)
self.OLD, # ours, orphaned <-
"Tap/apps/y@cloud_backup-5-20260712030000", # ours, orphaned <-
"Tap/apps/x@auto-2026-07-13_03-00", # periodic
"Tap/apps/x@cloud_backup-7-20260713030000", # another task
"Tap@manual-keepme", # human
]
assert sorted(self.collect(names)) == sorted(
[self.OLD, "Tap/apps/y@cloud_backup-5-20260712030000"]
)
class TestMountedSnapshots:
def test_it_reads_snapshot_names_out_of_the_mount_table(self, tmp_path):
import truecloud_nested as tn
mounts = tmp_path / "mounts"
mounts.write_text(
"tmpfs /run tmpfs rw 0 0\n"
"Tap/apps/x@snap1 /run/truecloud-nested/t/apps/x zfs ro 0 0\n"
"Tap/apps/y@snap1 /mnt/Tap/apps/y/.zfs/snapshot/snap1 zfs ro 0 0\n"
"Tap/live /mnt/Tap/live zfs rw 0 0\n"
)
live = tn.mounted_snapshots(str(mounts))
assert live == {"Tap/apps/x@snap1", "Tap/apps/y@snap1"}
assert "Tap/live" not in live # a live dataset is not a snapshot
class TestGarbageCollectorExecution:
def test_it_deletes_the_stale_ones_and_nothing_else(self, monkeypatch, tmp_path):
import datetime as dt
import truecloud_nested as tn
mounts = tmp_path / "mounts"
mounts.write_text("")
now = dt.datetime(2026, 7, 14, 12, 0, 0, tzinfo=dt.UTC)
mw = FakeMiddleware([
"Tap@cloud_backup-5-20260714115900", # current run
"Tap/apps/x@cloud_backup-5-20260713030000", # orphan <-
"Tap/apps/x@auto-2026-07-13_03-00", # periodic
"Tap/apps/x@cloud_backup-7-20260713030000", # other task
])
remaining = tn.gc_stale_snapshots(
mw, "cloud_backup-5", "Tap@cloud_backup-5-20260714115900",
now=now, mounts_file=str(mounts),
list_snapshots=mw.list_snapshots,
)
assert remaining == []
assert mw.snapshots == [
"Tap@cloud_backup-5-20260714115900",
"Tap/apps/x@auto-2026-07-13_03-00",
"Tap/apps/x@cloud_backup-7-20260713030000",
]
def test_a_busy_orphan_is_reported_not_swallowed(self, monkeypatch, tmp_path):
import datetime as dt
import truecloud_nested as tn
mounts = tmp_path / "mounts"
mounts.write_text("")
now = dt.datetime(2026, 7, 14, 12, 0, 0, tzinfo=dt.UTC)
orphan = "Tap/apps/x@cloud_backup-5-20260713030000"
mw = BusyMiddleware(
["Tap@cloud_backup-5-20260714115900", orphan],
busy=[orphan], busy_for=99,
)
remaining = tn.gc_stale_snapshots(
mw, "cloud_backup-5", "Tap@cloud_backup-5-20260714115900",
now=now, mounts_file=str(mounts),
list_snapshots=mw.list_snapshots,
)
assert remaining == [orphan]
def test_it_collects_NOTHING_when_the_query_fails(self, tmp_path):
# Cannot enumerate => cannot know what is ours => delete nothing.
import datetime as dt
import truecloud_nested as tn
mounts = tmp_path / "mounts"
mounts.write_text("")
# The ENUMERATION fails -- which is now a `zfs list` that cannot run, not a
# middleware query. (This test used to fake a failure of `.query`, a call
# production no longer makes, so it passed no matter what the code did.)
def broken_lister(_dataset):
raise tn.ZfsError("cannot open 'Tap': pool I/O is currently suspended")
mw = FakeMiddleware(["Tap/apps/x@cloud_backup-5-20260713030000"])
assert tn.gc_stale_snapshots(
mw,
"cloud_backup-5", "Tap@cloud_backup-5-20260714115900",
now=dt.datetime(2026, 7, 14, 12, 0, 0, tzinfo=dt.UTC),
mounts_file=str(mounts),
list_snapshots=broken_lister,
) == []
assert mw.snapshots, (
"cannot enumerate => cannot know what is ours => must delete NOTHING"
)
class TestEnumerationComesFromZfsNotMiddleware:
"""The bug that a source check can never catch, found only by running it.
Porting the deleted private `zfs.dataset.query` to the public
`pool.dataset.query` looked obviously right: the method exists, it is
documented, iX will not delete it. Every test passed and `compat.py` went green
on TrueNAS 26.
It was wrong. The public query applies a VISIBILITY POLICY -- on a real box it
returns 205 of 274 datasets, hiding `ix-apps/*`, `.system/*` and `.ix-virt/*`.
On the production pool that is 84 of 270, and `ix-apps` holds LIVE APPLICATION
DATA. The staging plan would have omitted every one of them, and `plan_staging`
would never have seen them, so they would not even appear in `skipped`. A green
backup, silently missing data -- the precise failure this module exists to
prevent.
The snapshot query lies the same way, so the sweep would orphan one snapshot per
hidden dataset, forever.
Hence: READ from ZFS, MUTATE through middleware. These tests hold that line.
"""
def test_query_filesystems_shells_out_to_zfs(self):
import truecloud_nested as tn
seen = []
class R:
returncode = 0
stdout = (
"scratch\t/mnt/scratch\tyes\n"
"scratch/ix-apps\t/mnt/scratch/ix-apps\tyes\n" # middleware HIDES this one
"scratch/.system\tlegacy\tno\n"
)
stderr = ""
def runner(cmd):
seen.append(cmd)
return R()
rows = tn.query_filesystems(runner=runner)
assert seen and seen[0][0] == "zfs", "must read ZFS, not call middleware"
names = [r["name"] for r in rows]
assert "scratch/ix-apps" in names, (
"ix-apps is exactly what pool.dataset.query hides, and exactly what "
"holds live app data. If it is not here the backup omits it silently."
)
# ...and it still speaks the shape the planner expects.
row = next(r for r in rows if r["name"] == "scratch/.system")
assert row["properties"]["mountpoint"]["value"] == "legacy"
assert row["properties"]["mounted"]["value"] == "no"
def test_a_failing_zfs_raises_rather_than_returning_an_empty_list(self):
# The whole failure class in one assertion. "No datasets" and "the command
# broke" must never look the same: a caller that cannot tell them apart
# stages nothing, sweeps nothing, and reports success.
import truecloud_nested as tn
class R:
returncode = 1
stdout = ""
stderr = "cannot open 'scratch': no such pool"
with pytest.raises(tn.ZfsError, match="no such pool"):
tn.query_filesystems(runner=lambda cmd: R())
with pytest.raises(tn.ZfsError):
tn.list_snapshot_names("scratch", runner=lambda cmd: R())
def test_list_snapshot_names_reads_the_whole_tree_from_zfs(self):
import truecloud_nested as tn
seen = []
class R:
returncode = 0
stdout = "scratch@s\nscratch/ix-apps@s\n"
stderr = ""
def runner(cmd):
seen.append(cmd)
return R()
names = tn.list_snapshot_names("scratch", runner=runner)
assert names == ["scratch@s", "scratch/ix-apps@s"]
assert "-t" in seen[0] and "snapshot" in seen[0] and "-r" in seen[0]
assert "scratch/ix-apps@s" in names, (
"pool.snapshot.query hides this; a sweep that cannot see it orphans it "
"on every single run, forever"
)
class TestTheProductionWiringIsWhatWeThinkItIs:
"""Tests of a seam prove nothing if production stops using the seam.
An audit mutation-tested this suite and found two regressions that reinstate the
exact bug this module exists to prevent, while all 293 tests still passed:
* swap `delete_snapshot_tree`/`gc_stale_snapshots`'s DEFAULT enumerator for one
that returns [] (which is what middleware's filtered query does for the 84
hidden datasets) -- green, because every test injected its own.
* put `pool.dataset.query` back into apply.sh's injected block -- green, because
nothing asserted what that block enumerates with.
Both are pinned here. These tests are about the WIRING, not the logic.
"""
def test_the_default_snapshot_enumerator_is_the_ZFS_one(self, monkeypatch, tmp_path):
# Called with no `list_snapshots=`, exactly as production calls it.
called = []
monkeypatch.setattr(tn, "list_snapshot_names",
lambda ds, **kw: called.append(ds) or [])
mw = FakeMiddleware(["Tap@snap"])
class NoRecursive(FakeMiddleware):
def call_sync(self, method, *args):
if method.endswith(".delete") and len(args) > 1:
raise RuntimeError("recursive delete unavailable")
return super().call_sync(method, *args)
tn.delete_snapshot_tree(NoRecursive(["Tap@snap"]), "Tap@snap")
assert called and set(called) == {"Tap"}, (
"delete_snapshot_tree's fallback sweep must enumerate from ZFS by default. "
"If it defaults to a middleware query, it cannot see the internal datasets "
"and orphans one snapshot per hidden dataset on every run."
)
called.clear()
mounts = tmp_path / "mounts"
mounts.write_text("")
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
tn.gc_stale_snapshots(mw, "cloud_backup-5", "Tap@cloud_backup-5-2026",
mounts_file=str(mounts))
assert called and set(called) == {"Tap"}, (
"the GC must enumerate from ZFS by default too"
)
def test_the_injected_block_enumerates_from_ZFS_not_middleware(self):
# apply.sh is a shell file holding the Python that gets injected into
# middlewared. Assert on what that block actually says.
with open(os.path.join(os.path.dirname(__file__), "..", "patch", "apply.sh"),
encoding="utf-8") as fh:
src = fh.read()
assert "_tc_nested.query_filesystems(" in src, (
"the staging plan must be built from query_filesystems() (which reads ZFS)"
)
# Match the METHOD NAME however it is quoted. An earlier version of this test
# only looked for the double-quoted form, so a single-quoted
# `call_sync('pool.snapshot.query')` -- including one passed in as the sweep's
# lister, which is the catastrophic case -- sailed straight through it.
import re
code = "\n".join(
ln for ln in src.splitlines() if not ln.lstrip().startswith("#")
)
offenders = re.findall(r"\b(?:pool|zfs)\.(?:dataset|snapshot)\.query\b", code)
assert not offenders, (
f"apply.sh references {sorted(set(offenders))}. Middleware's queries apply "
f"a visibility policy and hide ix-apps/*, .system/*, .ix-virt/* -- 84 of "
f"270 datasets on a real pool, including live app data. Enumerating from "
f"them omits those datasets from the backup SILENTLY, and sweeping from "
f"them orphans one snapshot per hidden dataset on every run."
)
class TestTheSnapshotNamespaceIsResolvedNotAssumed:
"""24.10/25.04 have only `zfs.snapshot`; 26 has only `pool.snapshot`.
Every one of these mutations used to pass the whole suite, because no test ever
built a non-default middleware generation:
* `_can_delete` -> always True (breaks 24.10: picks a namespace that isn't there)
* SNAPSHOT_SERVICES reversed (breaks 26)
* `snapshot_service` guessing instead of raising
"""
def test_a_24_10_box_deletes_through_zfs_snapshot(self):
mw = FakeMiddleware(["Tap@snap", "Tap/apps@snap"], snapshot_ns="zfs.snapshot")
assert tn.delete_snapshot_tree(mw, "Tap@snap",
list_snapshots=mw.list_snapshots) == []
assert mw.snapshots == []
methods = {m for m, _a in mw.calls}
assert methods == {"zfs.snapshot.delete"}, (
f"a 24.10 box has no pool.snapshot; called {methods}"
)
def test_a_26_box_deletes_through_pool_snapshot(self):
mw = FakeMiddleware(["Tap@snap", "Tap/apps@snap"], snapshot_ns="pool.snapshot")
assert tn.delete_snapshot_tree(mw, "Tap@snap",
list_snapshots=mw.list_snapshots) == []
assert {m for m, _a in mw.calls} == {"pool.snapshot.delete"}
def test_a_CRUDService_that_only_defines_do_delete_is_usable(self):
# `delete` is exposed FROM a method named `do_delete`. compat.py accepts both,
# so the runtime must too, or they disagree about the same box.
mw = FakeMiddleware(["Tap@snap"], delete_method="do_delete")
assert tn.snapshot_service(mw) == "pool.snapshot"
def test_a_registered_service_that_CANNOT_delete_is_not_chosen(self):
# The subtle one. `get_service()` only proves the namespace is registered.
# iX has already gutted a method while keeping its service
# (`pool.snapshot.do_update` on master). If the runtime settled for "the
# service exists", it would pick pool.snapshot, fail every delete, and orphan
# the whole tree -- while compat.py, which checks the METHOD, fell through to
# zfs.snapshot and reported the box healthy.
class GuttedPoolSnapshot(FakeMiddleware):
def get_service(self, name):
if name == "pool.snapshot":
# Registered, and `delete` IS still there -- inherited from
# CRUDService, which dispatches to a `do_delete` that no longer
# exists. This is the shape middlewared actually produces, and a
# naive `hasattr(service, "delete")` says YES to it.
gutted = _FakeSnapshotService(None)
assert callable(gutted.delete), (
"the fake must keep the inherited dispatcher, or it cannot "
"reproduce the bug"
)
return gutted
if name == "zfs.snapshot":
return super().get_service("zfs.snapshot")
raise KeyError(name)
mw = GuttedPoolSnapshot(["Tap@snap"], snapshot_ns="zfs.snapshot")
assert tn.snapshot_service(mw) == "zfs.snapshot", (
"must fall through to a namespace that can actually delete"
)
def test_no_usable_namespace_REFUSES_rather_than_guessing(self):
class Neither(FakeMiddleware):
def get_service(self, name):
raise KeyError(name)
with pytest.raises(StagingError, match="no usable snapshot delete"):
tn.snapshot_service(Neither())
def test_the_runtime_list_and_the_compat_manifest_cannot_drift(self):
# tools/compat.py claims "the runtime picks the same way ... so what this
# checks and what the patch does cannot drift apart." Nothing enforced that,
# and reordering SNAPSHOT_SERVICES silently broke the claim. Now it is bound.
sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "tools"))
import compat
call = next(c for c in compat.MIDDLEWARE_CALLS if c.id == "call-snapshot-delete")
checked = [compat.MiddlewareCall.namespace_of(m) for m, _p in call.options]
assert checked == list(tn.SNAPSHOT_SERVICES), (
f"compat checks {checked} but the runtime tries {list(tn.SNAPSHOT_SERVICES)} "
f"-- in THIS order. They must agree, or CI blesses a box that fails at run "
f"time."
)
assert set(compat.DELETE_NAMES) == set(tn.DELETE_METHODS), (
"compat and the runtime must accept the same delete spellings"
)
class TestWeOwnTheSweepEvenWhenWeDoNotStage:
"""TrueNAS 26 leak: stock's `recursive` rule is not the patch's `nested` rule.
<= 25.10 stock's create_snapshot calls get_dataset_recursive() -- the same
function this module vendors. "Stock went recursive" and "we have
something to stage" were the SAME question, so a non-staged snapshot
provably had no children and stock's non-recursive delete was correct.
26 stock uses filesystem.statfs: recursive = (path == the dataset's
mountpoint). Now the rules disagree. A dataset whose only descendants
are ZVOLs or legacy/none-mountpoint datasets gets a RECURSIVE snapshot,
while get_dataset_recursive() reports nothing to stage -- neither kind
is a mounted filesystem under `path`.
Stock then destroys the PARENT ONLY. With no staging tree there was no sidecar,
and the GC only ever ran from stage_nested -- so nothing on the box would ever
have found the children. One orphan per zvol/legacy descendant, on every run,
forever, while the backup reports SUCCESS.
Ownership of the sweep is therefore NOT conditional on staging.
"""
def test_own_snapshot_records_a_snapshot_it_did_not_stage(self, tmp_path, monkeypatch):
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
mw = FakeMiddleware(["Tap@cloud_backup-5-2026", "Tap/vm-zvol@cloud_backup-5-2026"])
root = tn.own_snapshot(mw, "cloud_backup-5", "Tap@cloud_backup-5-2026",
list_snapshots=mw.list_snapshots)
assert tn._read_sidecar(root) == ["Tap@cloud_backup-5-2026"], (
"the snapshot must be RECORDED even though nothing was staged -- the "
"sidecar is the only thing that makes the sweep happen"
)
def test_the_recorded_snapshot_is_then_actually_swept(self, tmp_path, monkeypatch):
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
# A recursive snapshot of a dataset whose only child is a ZVOL: exactly the
# 26 case. Nothing to stage, but the children are real.
mw = FakeMiddleware([
"Tap@cloud_backup-5-2026",
"Tap/vm-zvol@cloud_backup-5-2026",
"Tap/legacy-ds@cloud_backup-5-2026",
])
tn.own_snapshot(mw, "cloud_backup-5", "Tap@cloud_backup-5-2026",
list_snapshots=mw.list_snapshots)
# ...then the run finishes and cleanup fires, exactly as restic_backup's
# `finally` does.
tn.cleanup_task(mw, "cloud_backup-5", list_snapshots=mw.list_snapshots)
assert mw.snapshots == [], (
"the zvol/legacy children of an unstaged recursive snapshot were orphaned. "
"Stock deletes only the parent; if we do not own the sweep, nothing does."
)
def test_apply_sh_owns_the_snapshot_on_the_not_nested_path(self):
# The gate itself. It used to `return snapshot, snap_path` and hand the
# snapshot back to stock, whose delete is non-recursive.
with open(os.path.join(os.path.dirname(__file__), "..", "patch", "apply.sh"),
encoding="utf-8") as fh:
src = fh.read()
gate = src.index("if not nested:")
ret = src.index("return snapshot, snap_path", gate)
assert "_tc_nested.own_snapshot(" in src[gate:ret], (
"the not-nested path returns to stock without recording the snapshot. On "
"26 stock may have taken a RECURSIVE snapshot (its rule is statfs-based, "
"not ours) and deletes only the parent -- so every child is orphaned, with "
"no sidecar and no GC, on every run."
)
class TestASilentNoOpDeleteCannotDropTheSidecar:
"""A delete that returns without raising is not proof anything was destroyed.
iX has already gutted `pool.snapshot.do_update` on master into a no-op whose body
is commented out and which returns None. An AST check still sees the `def`; a
callable check still sees the method. If `do_delete` ever goes the same way, the
recursive delete returns cleanly, `delete_snapshot_tree` reports no survivors,
`cleanup_task` removes the sidecar -- the only record -- and ~250 snapshots are
orphaned forever with the backup reporting SUCCESS.
"""
def test_a_delete_that_does_nothing_is_caught_and_reported(self):
class NoOpDelete(FakeMiddleware):
def call_sync(self, method, *args):
self.calls.append((method, args))
return None # "succeeds", destroys nothing
mw = NoOpDelete(["Tap@snap", "Tap/apps@snap", "Tap/apps/lidarr@snap"])
survivors = tn.delete_snapshot_tree(
mw, "Tap@snap", list_snapshots=mw.list_snapshots, sleep=lambda _s: None,
)
assert sorted(survivors) == sorted(
["Tap@snap", "Tap/apps@snap", "Tap/apps/lidarr@snap"]), (
"a no-op delete must be REPORTED as survivors, so cleanup_task keeps the "
"sidecar and the next run reclaims them. Returning [] here silently "
"orphans the entire tree."
)
def test_an_unconfirmable_delete_keeps_owning_the_tree(self):
# If ZFS cannot be read we cannot confirm the delete did anything. Claiming a
# clean sweep makes cleanup_task DROP the sidecar -- and if the delete had in
# fact done nothing, the tree is orphaned with no record of it, forever.
#
# The two mistakes are not symmetric. A false survivor self-heals: the sidecar
# is kept, the next run reclaims it, the delete raises "does not exist", and
# the record clears. A lost record is permanent. So when in doubt, keep owning.
mw = FakeMiddleware(["Tap@snap"])
def cannot_enumerate(_dataset):
raise tn.ZfsError("pool I/O is currently suspended")
assert tn.delete_snapshot_tree(
mw, "Tap@snap", list_snapshots=cannot_enumerate, sleep=lambda _s: None,
) == ["Tap@snap"]
class TestTheMalformedRowGuard:
"""`zfs list -H` neither quotes nor escapes. A tab in a mountpoint splits wrong.
Dropping such a row would remove a dataset from the staging plan without it
appearing in `skipped` either -- the cardinal-rule failure, on the newest code
path. Two mutations (silently filtering the row; dropping the `fields=` argument)
used to pass the whole suite.
"""
@staticmethod
def _runner(stdout):
class R:
returncode = 0
stderr = ""
R.stdout = stdout
return lambda cmd: R()
def test_a_row_with_the_wrong_field_count_RAISES(self):
# A mountpoint containing a tab -> 4 fields, not 3.
bad = "scratch\t/mnt/scratch\tyes\nscratch/odd\t/mnt/od\td\tyes\n"
with pytest.raises(tn.ZfsError, match="tab-separated"):
tn.query_filesystems(runner=self._runner(bad))
def test_the_error_names_the_offending_row(self):
bad = "a\tb\tc\nbroken\trow\n"
with pytest.raises(tn.ZfsError, match="broken"):
tn.query_filesystems(runner=self._runner(bad))
def test_the_field_count_is_actually_enforced_for_snapshots_too(self):
with pytest.raises(tn.ZfsError):
tn.list_snapshot_names("Tap", runner=self._runner("ok\nnot\tok\n"))
def test_query_filesystems_asks_zfs_for_filesystems_only(self):
# Dropping `-t filesystem` would drag in volumes and snapshots, which the
# planner would then try to stage.
seen = []
def runner(cmd):
seen.append(cmd)
return self._runner("Tap\t/mnt/Tap\tyes\n")(cmd)
tn.query_filesystems(runner=runner)
assert "-t" in seen[0] and "filesystem" in seen[0]
assert "name,mountpoint,mounted" in seen[0]
class TestTheGarbageCollectorIsActuallyWiredIn:
"""The GC is the ONLY recovery path when the sidecar itself is gone.
The sidecar lives in /run (tmpfs), so a reboot mid-backup destroys it and orphans
the whole tree with nothing pointing at it. `own_snapshot` is the GC's only
production caller -- and stubbing that call out used to pass all 304 tests, i.e.
the GC could have been silently disconnected.
"""
def test_own_snapshot_runs_the_collector(self, tmp_path, monkeypatch):
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
ran = []
monkeypatch.setattr(
tn, "gc_stale_snapshots",
lambda *a, **kw: ran.append(a[1]) or [],
)
mw = FakeMiddleware(["Tap@new"])
tn.own_snapshot(mw, "cloud_backup-5", "Tap@new",
list_snapshots=mw.list_snapshots)
assert ran == ["cloud_backup-5"], (
"own_snapshot did not run the garbage collector. It is the only thing that "
"ever finds a tree whose sidecar was lost to a reboot."
)
def test_a_collected_orphan_is_carried_into_the_sidecar_if_it_survives(
self, tmp_path, monkeypatch
):
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
monkeypatch.setattr(
tn, "gc_stale_snapshots", lambda *a, **kw: ["Tap/x@busy-orphan"],
)
mw = FakeMiddleware(["Tap@new"])
root = tn.own_snapshot(mw, "cloud_backup-5", "Tap@new",
list_snapshots=mw.list_snapshots)
assert "Tap/x@busy-orphan" in tn._read_sidecar(root), (
"an orphan the GC could not delete must be RECORDED, or the next run has "
"no idea it exists"
)
class TestTheServiceIsResolvedLazily:
"""`_Snapshots.service` resolves on first use, not in the constructor.
Eager resolution looks harmless and is not: `gc_stale_snapshots` would raise inside
its own broad `except` and silently collect nothing, and `delete_snapshot_tree`
would raise `StagingError` out of the constructor -- outside its try -- instead of
returning survivors.
"""
def test_constructing_it_against_a_hopeless_middleware_does_not_raise(self):
class Neither(FakeMiddleware):
def get_service(self, name):
raise KeyError(name)
snaps = tn._Snapshots(Neither()) # must not raise
assert snaps.names is not None
with pytest.raises(StagingError):
snaps.delete("Tap@snap") # ...only the MUTATION refuses
class TestADatasetFromAnotherTreeMountedInsideThePath:
"""ZFS lets any dataset mount anywhere. A backup path is a DIRECTORY, not a tree.
Tank/photos mountpoint=/mnt/Tap/apps/photos
That dataset holds data inside the backed-up path, so its absence is a hole. And
`zfs snapshot -r Tap@...` does NOT cover it -- recursion follows the DATASET tree,
not the directory tree -- so there is no snapshot of it to stage.
It used to be scoped out by the dataset-NAME filter and then vanish: not staged,
not in `skipped`, no error. The backup reported SUCCESS with the data missing,
which is the cardinal-rule failure.
"""
def test_it_is_refused_loudly_not_omitted_silently(self):
foreign = DATASETS + [ds("Tank/photos", "/mnt/Tap/apps/photos")]
with pytest.raises(StagingError, match="Tank/photos"):
plan(datasets=foreign)
def test_the_error_explains_why_it_cannot_be_captured(self):
foreign = DATASETS + [ds("Tank/photos", "/mnt/Tap/apps/photos")]
with pytest.raises(StagingError, match="recursive snapshot"):
plan(datasets=foreign)
def test_a_foreign_dataset_OUTSIDE_the_path_is_still_ignored(self):
# Only datasets inside the backed-up path matter. Everything else on the box
# is none of our business, and reporting it would bury the ones that are.
elsewhere = DATASETS + [ds("Tank/photos", "/mnt/Tank/photos")]
mounts, skipped = plan(datasets=elsewhere)
assert len(mounts) == 6
assert skipped == []
class TestTheSeamsStayLateBound:
"""A default argument is frozen into `__defaults__` at def time.
`runner=_run`, `mounts_file="/proc/self/mounts"` and `sleep=time.sleep` were all
written that way, so `never_touch_the_real_system` could not intercept them: 19
tests read the REAL mount table -- one matching name away from running a real
`umount` on the NAS -- and the retry loop really slept for 20 seconds.
Re-freezing any of them silently re-arms that. The fixture cannot notice, because
it is the thing being bypassed. So assert it directly.
"""
def test_no_system_seam_is_frozen_into_a_default(self):
import inspect
offenders = []
for name in dir(tn):
fn = getattr(tn, name)
if not inspect.isfunction(fn):
continue
for default in fn.__defaults__ or ():
if default is tn._run or default is _REAL_SLEEP:
offenders.append(f"{name}() freezes {getattr(default, '__name__', default)!r}")
if default == "/proc/self/mounts":
offenders.append(f"{name}() freezes the real mount table")
assert not offenders, (
"these seams are frozen into __defaults__, so no test can intercept them "
"and they will reach the real system:\n " + "\n ".join(offenders)
+ "\nUse the late-bound idiom: `runner=None` + `runner = runner or _run`."
)
class TestOwnSnapshotCleansUpBeforeItBuilds:
def test_it_tears_down_a_crashed_run_before_recording_its_own(
self, tmp_path, monkeypatch
):
# A previous run may have died mid-flight. Its bind mounts still pin its
# snapshots (so they refuse to delete with EBUSY), and stacking a new staging
# tree on top of a stale one is how mounts leak.
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
order = []
monkeypatch.setattr(tn, "teardown", lambda *a, **kw: order.append("teardown") or [])
real_write = tn._write_sidecar
monkeypatch.setattr(
tn, "_write_sidecar",
lambda *a, **kw: order.append("write") or real_write(*a, **kw),
)
mw = FakeMiddleware(["Tap@new"])
tn.own_snapshot(mw, "cloud_backup-5", "Tap@new",
list_snapshots=mw.list_snapshots)
assert order == ["teardown", "write"], (
"own_snapshot must tear down a crashed run's tree BEFORE recording its own"
)
class TestStagingRefusesUpFrontIfItCouldNotSweep:
def test_a_middleware_with_no_usable_delete_refuses_before_restic_runs(
self, tmp_path, monkeypatch
):
# We are about to pin a recursive snapshot with bind mounts. If we could never
# sweep it, the honest move is to fail NOW -- not after restic has uploaded and
# the snapshot is already stuck.
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
class Hopeless(FakeMiddleware):
def get_service(self, name):
raise KeyError(name)
with pytest.raises(StagingError, match="no usable snapshot delete"):
tn.stage_nested(
Hopeless(), "/mnt/Tap", "Tap@snap", "Tap", "/mnt/Tap",
"cloud_backup-5", DATASETS, list_snapshots=lambda _d: [],
)
class TestQueryFilesystemsIgnoresMiddlewareEntirely:
"""`middleware` is accepted and IGNORED. That is the whole point of the function.
Reintroducing `if middleware: return middleware.call_sync("pool.dataset.query")` is
a two-line change that looks like an optimisation and reinstates the bug that
shipped once: middleware's query hides ix-apps/*, .system/*, .ix-virt/* -- 84 of
270 datasets on the real pool, including live app data -- and they would be omitted
from the staging plan without even reaching `skipped`.
"""
def test_passing_a_middleware_does_not_make_it_ask_middleware(self):
class Loud(FakeMiddleware):
def call_sync(self, method, *args):
raise AssertionError(
f"query_filesystems asked middleware ({method}). Its dataset query "
f"is FILTERED; enumeration must come from ZFS."
)
class R:
returncode = 0
stdout = "Tap\t/mnt/Tap\tyes\nTap/ix-apps\t/mnt/Tap/ix-apps\tyes\n"
stderr = ""
rows = tn.query_filesystems(Loud(), runner=lambda cmd: R())
assert [r["name"] for r in rows] == ["Tap", "Tap/ix-apps"]
class TestAnUnreadableZfsDuringTheByNameSweep:
def test_the_tree_is_still_owned_when_we_cannot_check(self):
# Recursive delete fails AND `zfs list` fails. We cannot know what is gone, so
# we must keep owning all of it: cleanup_task then KEEPS the sidecar and the
# next run reclaims. Reporting a clean sweep here drops the only record.
class NoRecursive(FakeMiddleware):
def call_sync(self, method, *args):
self.calls.append((method, args))
if method.endswith(".delete") and len(args) > 1:
raise RuntimeError("recursive delete unavailable")
return None # individual deletes "succeed" silently
calls = {"n": 0}
def flaky(dataset):
calls["n"] += 1
if calls["n"] == 1:
return ["Tap@snap", "Tap/apps@snap"] # the tree, for planning
raise tn.ZfsError("pool I/O is currently suspended") # ...then ZFS dies
mw = NoRecursive(["Tap@snap", "Tap/apps@snap"])
survivors = tn.delete_snapshot_tree(
mw, "Tap@snap", list_snapshots=flaky, sleep=lambda _s: None,
)
assert sorted(survivors) == ["Tap/apps@snap", "Tap@snap"], (
"with ZFS unreadable we cannot confirm anything was deleted. Returning [] "
"makes cleanup_task drop the sidecar and orphans the tree forever."
)
class TestTheSnapshotRecordIsNeverLostToAnUnreadableFile:
""""There is no sidecar" and "I could not READ the sidecar" are different facts.
Conflating them let `cleanup_task` take its `if not pinned` branch and UNLINK the
only record of a tree it had just failed to read.
"""
def test_an_unreadable_sidecar_raises_rather_than_reading_as_empty(self, tmp_path):
sc = tmp_path / "cloud_backup-5.snapshot"
sc.write_text("Tap@snap\n")
sc.chmod(0)
try:
with pytest.raises(OSError):
tn._read_sidecar(str(tmp_path / "cloud_backup-5"))
finally:
sc.chmod(0o600)
def test_a_missing_sidecar_is_simply_empty(self, tmp_path):
assert tn._read_sidecar(str(tmp_path / "nope")) == []
def test_cleanup_all_still_UNMOUNTS_when_a_sidecar_cannot_be_read(self, tmp_path):
# cleanup_all is what recover.sh and uninstall.sh call, i.e. it runs precisely
# when the box is already stuck. Its job is to get the mounts off. Aborting on
# one unreadable sidecar leaves the staging tree mounted -- which pins the
# snapshots, which is the state the caller is trying to escape.
sc = tmp_path / "cloud_backup-5.snapshot"
sc.write_text("Tap@snap\n")
sc.chmod(0)
unmounted = []
class R:
returncode = 0
stdout = ""
stderr = ""
def runner(cmd):
unmounted.append(cmd)
return R()
mounts = tmp_path / "mounts"
mounts.write_text(f"Tap@s {tmp_path}/cloud_backup-5 zfs ro 0 0\n")
out, _errors = tn.cleanup_all(
base=str(tmp_path), runner=runner, mounts_file=str(mounts),
glob_fn=lambda pat: [str(sc)],
)
assert sc.exists(), (
"cleanup_all DELETED the sidecar it had just failed to read. It has no idea "
"what that file names, and it may be the only record those snapshots exist."
)
sc.chmod(0o600)
assert any("umount" in " ".join(c) for c in unmounted), (
"cleanup_all stopped at the unreadable sidecar and never unmounted. The "
"staging tree stays mounted, pinning the snapshots -- which is exactly the "
"state recover.sh exists to escape."
)
assert "could not read the snapshot record" in "\n".join(out).lower()
class TestTheMountTableIsNeverGuessedAt:
def test_an_unreadable_mount_table_raises_rather_than_saying_nothing_is_mounted(self):
# Returning an empty set means "no snapshot is in use", which silently switches
# OFF the GC's only protection for a CONCURRENTLY RUNNING backup's snapshots.
# A first upload can easily run past the 1h age floor.
with pytest.raises(OSError):
tn.mounted_snapshots(mounts_file="/nonexistent/mounts")
def test_the_GC_actually_passes_in_use_through(self, tmp_path, monkeypatch):
# The `in_use` guard is well tested as a pure function -- but nothing checked
# that gc_stale_snapshots WIRES it in. Deleting the argument passed the suite.
monkeypatch.setattr(tn, "STAGING_BASE", str(tmp_path))
import datetime as dt
old = "Tap/apps/x@cloud_backup-5-20260713030000"
mounts = tmp_path / "mounts"
mounts.write_text(f"{old} /some/where zfs ro 0 0\n") # ...it is MOUNTED
mw = FakeMiddleware(["Tap@cloud_backup-5-20260714115900", old])
remaining = tn.gc_stale_snapshots(
mw, "cloud_backup-5", "Tap@cloud_backup-5-20260714115900",
now=dt.datetime(2026, 7, 14, 12, 0, 0, tzinfo=dt.UTC),
mounts_file=str(mounts), list_snapshots=mw.list_snapshots,
)
assert remaining == []
assert old in mw.snapshots, (
"the GC destroyed a snapshot that is still MOUNTED -- i.e. one a "
"concurrently running backup is reading from"
)
class TestPrefixCollisionsBetweenPools:
"""`Tap` and `Tap2` are different pools. String prefixes do not know that."""
def test_the_sweep_does_not_touch_a_similarly_named_pool(self):
mw = FakeMiddleware(["Tap@snap", "Tap/apps@snap", "Tap2/data@snap"])
tn.delete_snapshot_tree(mw, "Tap@snap", list_snapshots=lambda _d: list(mw.snapshots))
assert mw.snapshots == ["Tap2/data@snap"], (
"the sweep destroyed a snapshot in Tap2, a DIFFERENT POOL, because 'Tap2' "
"starts with 'Tap'"
)
def test_the_planner_does_not_stage_a_similarly_named_dataset(self):
noisy = DATASETS + [ds("Tap2/apps", "/mnt/Tap2/apps")]
mounts, skipped = plan(datasets=noisy)
assert len(mounts) == 6
assert skipped == []
def test_a_similarly_named_MOUNTPOINT_does_not_trip_the_foreign_check(self):
# /mnt/Tap2/x is not inside /mnt/Tap.
noisy = DATASETS + [ds("Tank/x", "/mnt/Tap2/x")]
mounts, skipped = plan(datasets=noisy)
assert len(mounts) == 6
def test_Tap2_is_not_a_child_of_Tap_even_when_mounted_inside_it(self):
# The one that actually bites: `Tap2/x` starts with the STRING "Tap", so a
# scope test that forgets the trailing "/" treats it as an in-tree descendant
# and STAGES it -- from a snapshot `zfs snapshot -r Tap@...` never took, since
# Tap2 is a different pool. It must be seen as FOREIGN and refused.
noisy = DATASETS + [ds("Tap2/x", "/mnt/Tap/apps/x")]
with pytest.raises(StagingError, match="Tap2/x"):
plan(datasets=noisy)
class TestTheForeignCheckDoesNotBreakWorkingConfigs:
def test_an_UNMOUNTED_foreign_dataset_is_skipped_not_refused(self):
# A locked/encrypted dataset contributes nothing to the live tree, so its
# absence is not a hole -- exactly as for an in-tree one. Raising here would
# turn a working nightly backup into a permanent failure the first time
# somebody locked a dataset.
datasets = DATASETS + [
ds("Tank/photos", "/mnt/Tap/apps/photos", mounted="no"),
]
mounts, skipped = plan(datasets=datasets)
assert len(mounts) == 6
assert ("Tank/photos", "dataset is not mounted (locked/encrypted?)") in skipped
def test_a_foreign_dataset_mounted_EXACTLY_AT_the_path_is_refused(self):
# One character wide: `mp.startswith(path + "/")` misses `mp == path`. And this
# case is the worse one -- it SHADOWS the base dataset's own directory, so we
# would stage what is hidden underneath instead of the data actually there.
datasets = DATASETS + [ds("Tank/x", "/mnt/Tap")]
with pytest.raises(StagingError, match="Tank/x"):
plan(datasets=datasets)
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