yonluandClaude Opus 5
a4ada725a2
v2 installed two globals and the fake replaced both. v3 has neither — the runtime is an npm module and the generated bindings call into it. What it has instead is better: setTransport() is a public seam for replacing the IPC transport, and *every* runtime call goes through it, so the fake is smaller than v2's and covers strictly more. The event dispatcher is no longer mirrored at all. v2's fake reimplemented desktop/events.js — the listener list, maxCallbacks expiry, the reverse iteration — because there was no way to reach the real one; emit() now goes through window._wails.dispatchWailsEvent, which is the entry point the backend's own push uses. What is mirrored instead is one line of Go: how EventManager.Emit packs variadic data into an event's single data field. Registration and unregistration are the public Events API. The one non-public thing left is the listener registry, aliased in vitest.config.mts and used only by listenerNames() — a test asks whether importing a store subscribed it, which nothing public can answer. A binding carries a method ID, not a name, so the fake derives the ID -> path map from the generated tree: FNV-1a over the FQN, with the Go type's casing recovered from each package's index.ts, which is the only place it survives (library/library.ts cannot tell you it is FrontendUtil). The map has to be complete rather than lazy because 21 assertions read calls() with no argument and compare the whole list. Two things had to move that are not the fake. fixture() drains microtasks between two renders: a v3 binding settles several hops later than v2's, and tests were already written as though fixture() meant "mounted and loaded". Microtasks and not a timer, which would hang under the suites that install fake ones. tracklist-store keeps its defaults on an empty answer instead of emptying the column list. GetTrackListColumns substitutes DefaultColumns only when the whole config section is missing; a section that exists with no columns returns nothing. Until now this was accidental — the binding was typed Column[], an absent answer arrived as undefined, and .map threw into the catch. 757 tests pass across all 63 files. They are run in batches: a single browser session dies partway through the 58 it queues, which reproduces unchanged at the pre-migration commit and is a resource limit on this machine rather than anything here. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01UDCbcCZQepnpSQYJ6SxxZm
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The component and store tier (make ui-test)
757 tests in a real Chromium with no Wails, no backend, no seeded library and no virtual display. This is the cheapest coverage available and where the bulk of UI regression belongs.
make ui-setup # once: the Vitest provider's own Chromium
make ui-test # behaviour only
make ui-watch
make ui-visual # + toMatchScreenshot baselines (YJ_VISUAL=1)
make ui-visual-update # re-record them
make ui-test UI_ARGS='store/queue' # filter
How it works
Wails v3 routes every runtime call — bindings, event emits, window,
dialogs, clipboard — through one IPC transport, and setTransport() is
a public seam for replacing it. So
frontend/test/support/wails-fake.ts replaces that and nothing
else, and the tests then exercise the real generated bindings, the
real runtime and the real store code. No module mocking, and no
second description of the Wails layer.
A binding call carries a method ID (an FNV-1a hash of the Go method's
fully-qualified name), not a name, so the fake derives the ID → path
map from the generated tree at setup: each package's index.ts
re-exports its service under the Go type's real name, which is the one
place that casing survives. A path that never maps records as #<id>
and fails the assertion naming it.
emit(Events.QueueChanged, payload); // push a backend event
stub('queue.Queue.GetState', state); // a value, or a function of the args
stubFailure('queue.Queue.SetQueue'); // reject, as a Go error does
calls('queue.Queue.SetQueue'); // what the frontend called back with
lastArgs('queue.Queue.SetQueue');
const el = await fixture('now-playing'); // mount; shadow()/text() query it
Delivery is not mirrored — emit() goes through the runtime's own
window._wails.dispatchWailsEvent, which is the entry point the
backend's push uses, so listener expiry and ordering are the runtime's
real code. What is mirrored is one line of Go: how
EventManager.Emit packs variadic data into an event's single data
field (none is null, one is the value, more is the slice).
A frontend Events.Emit no longer notifies local listeners before Go —
v3 calls the backend, which sends the event back out to every window.
The page still sees its own emit, one round trip later rather than
synchronously.
Five things that will cost you time
- Store singletons are constructed at module import, before any test
can stub.
test/setup.tstherefore carries import-time defaults for the stores that read config in their constructor. Without one, a store cachesundefinedwhere Go would have sent[], and components crash on.length— which reads exactly like a component bug and is not. Adding a store that reads config on construction means adding its default there. vitest.config.mts, not.ts— itmergeConfigs the repo'svite.config.mtsto reuse the@go/@store/@componentsaliases, and a.tssibling cannot import it.- Screenshots need the theme. The setup file imports
@store/theme-storefor its side effect (it applies the--yj-*ramp to:root); without it a component renders white-on-white and the baseline is blank. @lit-labs/virtualizernever produces two identical frames, sotoMatchScreenshoton<queue-panel>fails with "could not capture a stable screenshot" rather than a diff. Assert on its rows instead.- A v3 binding settles several microtasks after a v2 one did — it
goes through
Call(), an asyncruntimeCallWithID, the transport and aCancellablePromise, where v2'swindow.goproxy resolved one promise.fixture()drains microtasks between two renders so a component that loads infirstUpdatedis loaded when it returns. Microtasks and not a timer, deliberately: a timer hangs forever under the suites that install fake ones.
Visual baselines are font-hinting and compositing sensitive, which is why they are opt-in: they only mean anything on the machine that recorded them.
Bindings
frontend/bindings/ is generated by wails3, not by go generate,
so the pre-commit codegen check does not cover it — a renamed Go bound
method first shows up at runtime, as a call that never settles.
make bindings-check # ~3.5 s warm, also a pre-commit hook
make bindings # regenerate for real
No build tags are passed: the generator is a static analyser that sees only the configuration it is told about, and the one that matters is the one users run, which is the default tag set.