Testing

Summary of docs/PLAN.md section 3. SPEC 19 lists the required behaviours; Appendix A of the plan maps each SPEC 19.x item to the package whose tests cover it.

Hermetic by default

cargo test --workspace needs no external service, no network (loopback only) and no Docker:

Storage::in_memory (MemMetaStore + MemBlobStore) stands in for CockroachDB and S3. It is a faithful model: strictly serializable (one mutex over im maps), stale snapshots for Consistency::Stale, forced transaction failures (fail_txn_every), and the exact CAS / ON CONFLICT DO NOTHING / landed-uniqueness semantics of docs/contracts/storage-semantics.md.
scion_server::testing::InProcessServer serves on loopback with TLS certificates generated per test, so SPEC 17 is exercised even in unit tests.
scion_daemon::testing::InProcessDaemon serves on a temporary Unix socket.
scion_testkit::FakeGitHub (axum on loopback) and scion_testkit::FakeUpstream (an in-memory scion.v1 upstream) replace GitHub and the server for client and daemon tests.
Temporary directories come from tempfile.

The git CLI is optional: differential tests (git check-ignore, git ls-tree, git blame, git merge-file) and fixture builders print SKIP: git not found and pass when it is absent. Vendored bundles under corpus/git/ are read with gix.

Fault injection and oracles

scion_core::FaultRegistry arms named points: scion_core::fault::points (SPEC 5.3 steps, land, redaction), scion_wc::points (client operations), and the storage decorator points meta.<method>.before|after / blob.<method>.before|after. Actions: Error(code), Crash (latches until reset), Delay, FailAfter (effect applied, then UNAVAILABLE).
Storage access counters (scion_store::Counters, CounterSnapshot) back the complexity gates.
Oracles: the independent reference model (scion-refmodel), frozen golden vectors (testdata/golden/), scion_store::fsck (SPEC 4.5), the linearizability checker (scion_testkit::lincheck), the whole-system differential (P32) and the external git differentials.

Heavy counts

Default runs use scion_core::test_support::proptest_cases(N) (about 10^4 where the SPEC asks for 10^6, 10^3 where it asks for 10^5). Spec-sized runs are #[ignore] tests named full_*.

Variable	Effect
`SCION_PROPTEST_CASES`	Overrides every `proptest_cases(default)`
`SCION_FULL=1`	Set by `scripts/check.sh --full`; `scion_core::test_support::full_mode()` returns true

External backends (gated)

Variable	Meaning
`SCION_TEST_CRDB_URL`	e.g. `postgresql://root@localhost:26257/defaultdb?sslmode=disable`; each test creates `scion_test_<random>`
`SCION_TEST_S3_ENDPOINT`	Gate for S3 tests, e.g. `http://localhost:9000`
`SCION_TEST_S3_BUCKET`	Default `scion-test`
`SCION_TEST_S3_ACCESS_KEY`, `SCION_TEST_S3_SECRET_KEY`	MinIO defaults `minioadmin` / `minioadmin` in `scripts/test-external.sh`
`SCION_TEST_S3_REGION`	Default `us-east-1`

Gated tests are named external_*; without their variables they print SKIP: ... and pass. scion_conformance::Backend::from_env() adds the External backend to the conformance suites when both gates are set.

Commands

Command	What it runs
`scripts/check.sh`	`cargo fmt --all -- --check`, `cargo build --workspace --all-targets`, `cargo test --workspace`, `cargo clippy --workspace --all-targets -- -D warnings`, `scripts/check-layers.sh` (the definition of done of every package)
`scripts/check.sh --full`	The above, then `SCION_FULL=1 cargo test --workspace --release -- --include-ignored` (conformance is claimed only on a full run)
`scripts/check-layers.sh`	PLAN 1.3 layer allow-table check over `cargo metadata`
`scripts/check-layers.sh --self-test`	Proves that injected forbidden edges are rejected
`docker compose -f docker/compose.test.yml up -d --wait`	CockroachDB (single node, insecure, 26257) and MinIO (9000) with the `scion-test` bucket
`scripts/test-external.sh`	Exports the gate variables and runs `cargo test --workspace -- external_`
`scripts/test-external.sh --all`	Exports the gate variables and runs the whole workspace test suite (conformance suites also use the External backend)
`RUSTDOCFLAGS="-D warnings" cargo doc --workspace --no-deps`	Documentation must build without warnings

Where tests live

Unit tests: inside the owning module (#[cfg(test)]).
Crate integration tests: crates/<crate>/tests/<prefix>_*.rs, with shared helpers in tests/<prefix>_support/mod.rs; prefixes are listed in each package's owns.
Cross-cutting SPEC 19 suites: crates/scion-conformance/tests/*.rs, one file per package.
Reusable scenarios: src/testing.rs behind a testing feature (scion-server, scion-daemon, scion-wc, scion-import), because integration-test modules cannot be imported across crates.

Dependency rule: scion-core, scion-object, scion-proto and scion-refmodel (the crates scion-testkit depends on) must not dev-depend on scion-testkit; scripts/check-layers.sh enforces it. scion-refmodel has no scion dependency of any kind.