Give every write-snapshot fixture a root of its own

[thedavidmeister]

Closes #225.

What was wrong

freezeConsensusFixture() named one directory itself —
src/generated/writeConsensusNotATag — and two tests called it.
testWriteSnapshotRecordsTheZoltuAddress and
testWriteSnapshotHashesTheCodeItRecords each write a snapshot there, read it
back out of the file, and remove the directory. Forge runs a contract's tests
concurrently, so the removal of whichever finished first lands between the
other's write and its read, and the other fails on a path that existed when it
was named.

The failure is a cheatcode error rather than an assertion — an ENOENT out of
vm.writeFile or vm.readFile on
src/generated/writeConsensusNotATag/MockDeployable.sol — so it reads as a
defect in whatever change is under test rather than as the race it is. It is
invisible under the full suite, which is why nothing caught it.

What I chose, and what the defaulting overloads needed

Nothing, as it turns out, and that is the whole of the design question #225
raises.

#226 is why. Before it, writeSnapshot's only output directory was
LibFs.dirForTag(dir) — src/generated/<dir>, the record frozenSnapshotPaths
walks — so a test of the writer could only be a test that wrote into the
committed tree, and a fixture there could not be given a root of its own.
#226 replaced that path with LibFs.buildFileForContract(vm, deployed, dirForSnapshot(root, dir), ...), the overload that takes the directory it
writes into, on BOTH arities and required. dirForTag survives in this library
only inside the DEFAULTING path spellings — dirForSnapshot(dir) and
pathForSnapshot(dir, contractName) — which name the real record and are not
writers at all.

So the library already had everything these fixtures needed; the tests were
never repointed, and kept passing LIB_FS_ROOT out of the habit #226 removed
the reason for. The fix is in the tests, and it is the rule the repo already
follows elsewhere — RainDeployVerifySnapshotTest gives each lib writer its own
root under ./fixture-lib, one per test.

Every write-snapshot fixture whose assertion is about the file's BYTES moves to
a root of its own under FIXTURE_ROOT, the tree #232's setUp clears:

test	root
testWriteSnapshotDeclaresTheLicenceItWasHanded	test/generated-snapshot/write-header
testWriteSnapshotRecordsTheDeployment	test/generated-snapshot/write-record
testWriteSnapshotDeclaresTheDeployConstantsInOrder	test/generated-snapshot/write-order
testWriteSnapshotFreezesTheDependencyList	test/generated-snapshot/write-dependencies
testWriteSnapshotRecordsTheZoltuAddress	test/generated-snapshot/write-consensus-address
testWriteSnapshotHashesTheCodeItRecords	test/generated-snapshot/write-consensus-code
testWriteSnapshotDefaultsToTheOrgHeader	test/generated-snapshot/write-defaults

That the bytes are root-independent is not assumed: it is what
testWriteSnapshotWritesUnderTheRootItIsHanded already asserts, comparing the
file written at a fixture root against the file written at LIB_FS_ROOT for the
same inputs. No assertion in any of the seven changes.

The two helpers a test reaches for a fixture write — freezeConsensusFixture
and freezeDependencies — take the root from the CALLER now. A helper that
names its own directory is the defect: a second test reaching it shares that
directory by construction, which is how one test became two sharing one path
without anything saying so.

THREE fixtures stay in the real src/generated/, each its own directory and
none shared, because for each of them the real record IS the property:

• testWriteSnapshotWritesTheSnapshotAtItsPath — that the DEFAULTING path
  spelling names where the writer lands.
• testWriteSnapshotWritesUnderTheRootItIsHanded — it writes at both roots by
  construction, and asserts the real record was not written under the fixture
  root's name.
• testWriteSnapshotRefusesARootThatClimbsOutOfTheTreeItNames — it asserts an
  escaping root's write never arrives there.

setUp's NatSpec said "the defaulting writers" of the whole family; it now names
those three and why each is one.

Two fixture roots also move under FIXTURE_ROOT:
test/generated-write-snapshot-root -> test/generated-snapshot/write-rooted
and test/generated-escape-root -> test/generated-snapshot/escape-root. #226
said both belonged in #232's clear list; the two landed eighteen minutes apart
and neither moved them, so until now a failed run left them outside the tree
setUp clears. The escape root's climb is re-counted for the extra segment —
../../../src/generated — so it still resolves to the real record, which is
what the test's expected-absent path is about.

The two constraints

• LibFs.dirForTag confines snapshot writes to the record
  frozenSnapshotPaths walks. It did, and Generate the rolling snapshots under the record root they are frozen from #226 is where that stopped being
  true of the writer: writeSnapshot goes through
  LibFs.buildFileForContract(dir, ...) at dirForSnapshot(root, dir), and
  requireRecordRoot is what makes the root an argument rather than a hole.
  dirForTag still confines the two DEFAULTING spellings, which is why the
  three tests above still use them and the other seven no longer do. Nothing
  walks a test/generated-snapshot/write-* root as a record.
• Forge runs a contract's tests concurrently. That is the rule
  FIXTURE_ROOT now states rather than the accident this was: one root per
  test, because a fixture snapshot is read back out of the file it was written
  to, so two tests under one root is one test's removeDir landing between the
  other's write and its read. setUp is still the only safe place to clear, and
  it runs once before any of them.

QA

• Discriminating tests: testWriteSnapshotRecordsTheZoltuAddress and
  testWriteSnapshotHashesTheCodeItRecords, both pre-existing and both left
  asserting exactly what they asserted. They ARE the discrimination, and it is a
  RATE rather than a single run, because an intermittent failure is the whole of
  what The testWriteSnapshot family shares one fixture directory and races itself #225 names: forge test --match-contract LibRainDeploySnapshotTest, with
  git clean -fdq test src && rm -rf fixture-lib cache/fuzz before every run, is
  5 red of 20 on main at 2e21422 and 0 red of 40 on this branch.
  Every one of those 5 reds is one of these two tests, ENOENT on
  src/generated/writeConsensusNotATag/MockDeployable.sol and on nothing else —
  4 out of vm.writeFile, 1 out of vm.readFile.
• Mutations applied: one, and it is the fix reverted rather than a source line,
  because this PR changes no source. testWriteSnapshotHashesTheCodeItRecords
  is pointed back at CONSENSUS_ADDRESS_FIXTURE_ROOT, so the two tests share one
  root again with every other change on the branch left in place: 10 red of 20, against 0 red of 40 unmutated. Every red is one of these two tests on test/generated-snapshot/write-consensus-address/candidate/MockDeployable.sol and on nothing else — 4 runs out of vm.writeFile, 3 out of vm.readFile, 2 out of vm.removeFile, 1 a Directory not empty out of vm.removeDir: one shared-directory race in four of its spellings.
  A mutation harness cannot express this one — it counts a suite failure as a
  killed mutant, and a test that fails on its own schedule is exactly the input
  The testWriteSnapshot family shares one fixture directory and races itself #225's "Consequence for this repo's own tooling" section says turns arbitrary
  survivors into false kills. The instrument for an intermittent defect is the
  rate, so the rate is what is reported.
• Oracle: the expected values are the ones the two tests already assert, and
  neither moved — the EVM's own CREATE2 derivation over
  LibRainDeploy.ZOLTU_FACTORY, a zero salt and keccak256(creationCode) for
  the address, and the snapshot's own RUNTIME_CODE hashed for
  BYTECODE_HASH. What this PR had to establish independently is that the file
  is the same file under a fixture root, and that oracle is
  testWriteSnapshotWritesUnderTheRootItIsHanded, which compares the bytes
  written at a fixture root against the bytes written at LIB_FS_ROOT — a
  pre-existing test, unchanged here, rather than an assertion this PR writes
  about its own move.
• Category check: The testWriteSnapshot family shares one fixture directory and races itself #225 asks for one thing — that a test in the
  testWriteSnapshot* family owns its fixture directory alone, against the
  intent oracle that this repo already does that everywhere else. Covered: the
  one shared directory is two directories, the helper that named it takes the
  root from its caller, and the rule is stated at FIXTURE_ROOT so a root added
  later is covered by being under a tree that is cleared and by a rule that is
  written down. No test is deleted, skipped, serialised or weakened.

Verification

git clean -fdq test src && rm -rf fixture-lib cache/fuzz before every run,
.env.example with drpc/publicnode endpoints substituted for hyperevm, arbitrum
and bsc. out/ cleaned between forge lint and forge test.

• Whole suite on main at 2e21422: 566 passed, 0 failed of 566.
• Whole suite on this branch: 566 passed, 0 failed of 566.
• git status clean after both, and src/generated/ is untouched by either.
• forge fmt --check clean. forge lint: clean, zero diagnostics at its default
  severity, with out/ removed first.
• No two fixture roots in the file are the same string: 36 distinct
  test/generated-snapshot/* literals, each appearing exactly once. That is the
  invariant the fix is, checked on the committed tree rather than read off the
  run above it.

🤖 Generated with Claude Code

https://claude.ai/code/session_01V8ViHcKLVk2YoS2joH4HdN

Summary by CodeRabbit

• Tests
  • Isolated snapshot test fixtures under dedicated test roots to prevent cross-test interference.
  • Added coverage confirming snapshot writes remain within the specified root and reject path traversal.
  • Improved cleanup of complete test fixture roots.
  • Separated dependency and consensus snapshot fixtures to preserve independent rollback behavior.

[coderabbitai]

Walkthrough

The snapshot test suite now assigns dedicated fixture roots to each test. Snapshot helpers accept explicit roots, and cleanup removes complete isolated roots. Tests cover rooted writes, traversal rejection, dependency and consensus snapshots, record ordering, and header equivalence.

Changes

Snapshot fixture isolation

Layer / File(s)	Summary
Fixture root contracts test/src/lib/LibRainDeploySnapshot.t.sol	Fixture documentation and rooted fixtures define isolated roots and traversal behavior.
Record and ordering fixtures test/src/lib/LibRainDeploySnapshot.t.sol	Licence-header, deployment-record, and declaration-order tests write and clean dedicated roots.
Dependency and consensus fixtures test/src/lib/LibRainDeploySnapshot.t.sol	Dependency and consensus helpers accept explicit roots. Related consistency checks use separate roots.
Header equivalence fixture test/src/lib/LibRainDeploySnapshot.t.sol	Defaulted and explicit snapshot headers use one isolated record root with root-level cleanup.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: claude

Merge Risk: 🟡 Moderate · up to d2216

Concurrent Forge tests can still delete another test’s fixture while it is in use, causing intermittent failures. Cleanup should be isolated before merge.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: assigning each write-snapshot fixture its own root directory.
Linked Issues check	✅ Passed	Issue #225 requires each testWriteSnapshot* filesystem-writing test to own a fixture directory. The PR summary states that seven byte-based fixtures now use distinct roots under FIXTURE_ROOT, and …
Out of Scope Changes check	✅ Passed	The changes are limited to test/src/lib/LibRainDeploySnapshot.t.sol. They update fixture roots, helper parameters, cleanup paths, and related path calculations. These changes directly support the is…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-225-race

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Actionable comments posted: 1

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Inline comments:
In `@test/src/lib/LibRainDeploySnapshot.t.sol`:
- Line 95: Update LibRainDeploySnapshotTest.setUp() to stop recursively clearing
the shared FIXTURE_ROOT; move cleanup into beforeTestSetup(bytes4 testSelector)
and clear only the fixture root assigned to the current test, preserving
isolated cleanup without deleting parallel tests’ descendants.

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