test(nexus): migrate hand-rolled decide/react tests onto the fixtures (#238)#299
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…#238) Route pure decide-only and react-only tests through `nexus::testing::AggregateFixture` / `SagaFixture` — the intended given/when/then surface — instead of hand-rolling `AggregateRoot::new -> handle/react -> assert`. The fixture drives the real replay path for `given`, so each migrated test now also proves the decision behaves correctly *after rehydration*, not just on a bare root. Adds fixture usage to four more test files: - aggregate_root_tests: the 5 `Handle` decide tests -> given/when/then. - saga_tests: the 3 `React` tests -> `SagaFixture` (and asserts the projected intent via `then_expect_commands`, which the hand-rolled version never checked). - integration_test / newtype_aggregate_tests: invariant-rejection and rehydrate->state assertions -> fixture, using `given(history)` to replace the `commit_persisted` setup. One `commit_persisted`+version lifecycle test is kept hand-rolled in each file — `when` folds state but deliberately does not advance the version, so version progression is not the fixture's job. `then_expect_events` requires `EventOf<A>: PartialEq + Debug`, so `CounterEvent` (aggregate_root) and the `UserEvent` tree (integration) gain a `PartialEq` derive. Local error types have no `PartialEq`, so rejections assert with `then_expect_error_matching`. Premise corrections (from reading the code, not the issue's line numbers): the two listed store-side targets are not migrated. The fixture is a closed assertion DSL that never returns the `AggregateRoot`, so tests needing its `version()` / raw state cannot use it — `property_tests`' `replay_events`/`apply_events_to` feed proptest properties that inspect the root and exercise the replay contract itself, and `repository_qa_tests`' equivalents no longer exist. Adds a "When NOT to use the fixture" section to the `src/testing.rs` module docs — the sole production change — recording the boundary: `replay`/version-contract tests, version/`commit_persisted` progression, and store-owned load/replay lifecycle all stay hand-rolled. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What
Migrates the hand-rolled decide-only / react-only kernel tests onto
nexus::testing::AggregateFixture/SagaFixture— the intendedgiven/when/then surface — instead of open-coding
AggregateRoot::new → handle/react → assert. Closes #238.Because
givendrives the real replay path, each migrated decide test now alsoproves the decision holds after rehydration, not just on a bare
new()root —strictly more coverage than the originals.
Fixture adoption goes from 2 dedicated files to 6; net +162 / −159 (collapsed
scaffolding). 153/153 kernel tests pass; full
nix flake checkgreen.Migrated
aggregate_root_testsHandledecide tests (CounterEventgainsPartialEq)replay/commit_persisted/restore/ version testssaga_testsReacttests →SagaFixture(+ athen_expect_commandsintent-projection assertion the original lacked)correlatetested directlyintegration_testgiven-history (UserEventtree gainsPartialEq)commit_persisted+version lifecycle testnewtype_aggregate_testsnew()-contract testsPlus
kernel.rs: allowunused_must_usefor the terminalthen_expect_*chains.The recurring transform:
create → commit_persisted → assert a later command is rejectedcollapses togiven([events]).when(cmd).then_expect_error_matching(...).Production change (one)
src/testing.rsgains a "When NOT to use the fixture" doc section recordingthe boundary (replay/version-contract tests, version/
commit_persistedprogression, and store-owned lifecycle all stay hand-rolled).
Deviations from the issue (surfaced, not silent)
numbers) showed they can't be. The fixture is a closed assertion DSL that
never returns the
AggregateRoot, butproperty_tests'replay_events/apply_events_tofeed proptest properties that inspect.version()/raw state and exercise the replay contract itself, andrepository_qa_tests' equivalents no longer exist. Consistent with the issue'sown "out of scope" carve-out.
concern; each file keeps its local toy domain (a dedicated crate for shared
toy domains is likely overkill, revisit under test: consolidate duplicated toy test-domains into one shared, fixture-friendly module #239).
Test plan
nix flake check— all six checks pass (clippy, doc, fmt, toml-fmt, audit,deny, nextest, hakari).
cargo clippy -p nexus --all-targetsclean (flake gate is lib-only).🤖 Generated with Claude Code