Lands the fake HTTP server, the patch fixture pipeline, and the first
two scenarios that exercise the real FFI path end-to-end. Plus a test
that would have caught the patch-to-release rollback bug
(shorebirdtech/shorebird#3728).
Architecture follows the principles surfaced in review:
- Dart tests call the public `ShorebirdUpdater` API only — never the
raw `Updater` FFI wrapper, never the engine API.
- Engine API stays inside the `library_test_hooks` Rust crate.
`shorebird_test_init` constructs `AppParameters` + stub
`FileCallbacks` internally so Dart never sees those types.
`shorebird_test_simulate_successful_launch` wraps the
start/success protocol so the Dart layer never knows there's a
protocol — it just knows "the engine reported a successful boot."
- ffigen scans only the test_hooks header. The engine header
(updater_engine.h) does not appear in the Dart bindings.
- A `TestEngine` Dart helper concentrates engine-side simulation in
one place; the test bodies stay focused on `ShorebirdUpdater`.
Implementation choices worth flagging:
- FFI calls run via `Isolate.run`. Synchronous run blocks the main
isolate, deadlocking against the in-isolate shelf server. The
test's IsolateRun callback re-opens the cdylib (cheap: dlopen is
ref-counted) and resets `Updater.bindings` in the sub-isolate
because Dart isolates do not share static fields.
- `libapp_path` must be a real file on the desktop integration build:
the non-Android non-iOS non-test `patch_base` reads it directly
from disk. Tests that install a patch write the fixture's `base`
bytes to `libapp.so` before init.
- Fake server kept minimal: shelf, no Range support, no auth, no
concurrency knobs. Stage 3+ scenarios (download cutoff, hash
mismatch loop, etc.) extend it as needed.
Three scenarios cover three reasons we wanted this suite:
1. `checkForUpdate returns upToDate when server has no patch` —
baseline: confirms the harness boots cleanly and returns the
expected enum.
2. `install a patch and boot from it` — golden path: check →
update → simulateSuccessfulLaunch, then assert
`readCurrentPatch` / `readNextPatch` / `checkForUpdate`
transitions match the public API contract.
3. `checkForUpdate returns restartRequired after patch-to-release
rollback` — regression for shorebirdtech/shorebird#3728. Pre-fix
this returned `upToDate` and left no signal to prompt a restart.
Verified locally: 232 Rust unit tests + 44 Dart tests (41 existing
unit + 3 new integration) green; clippy/fmt/cspell clean.
Eric Seidel
96fd32796e