August 17, 2026
Fission 0.11.1: Web LiveTest
Fission 0.11.1 extends the existing LiveTest contract to real Web applications.
Tests can now launch Chromium, query the Fission semantic tree, use semantic
selectors, inject deterministic input, control time, wait for application state,
and capture PNG screenshots through the same LiveTestClient used by native
shells.
One testing vocabulary
Web testing reuses TestCommand, SelectorQuery, TestEvent, and
TestResponse. Canvas-rendered widgets are selected through Fission semantics,
not a parallel DOM-selector model:
let client = LiveTestClient::launch_browser(
BrowserTestOptions::new("http://127.0.0.1:8080/").fission_canvas(),
)?;
client.wait_for_text("Inbox", 5_000)?;
client.tap_semantic_identifier("inbox.compose")?;
client.fill_text_semantic_identifier("message.subject", "Hello from Web")?;
client.wait_for_idle(5_000, true)?;
let screenshot = client.capture_screenshot_png()?;
Native callers continue to use LiveTestClient::connect(port). The client API
above is additive, and the existing native transport is unchanged.
The CLI proves live control
fission test --target web now performs more than a canvas-ready smoke check.
It builds test-control-enabled WASM, serves it on an ephemeral loopback port,
launches an isolated headless Chromium profile, pumps the Web event loop, and
queries the running Fission semantic tree. Build failures, browser errors,
bridge failures, and protocol errors fail the command.
Ordinary Web builds do not install the test bridge. The bridge opens no
application control port and is selected only when producing a Web test build.
Intentionally bounded
This first release supports Chromium without adding Playwright, Selenium, or
WebDriver. Its input commands enter through Fission's deterministic event path;
they do not claim to be browser-generated trusted events. Screenshots capture
the browser page, including the canvas and browser-composited surfaces, rather
than reading back a WebGPU texture. Tests inspect the Fission semantic tree,
while browser accessibility-tree assertions and Firefox/WebKit drivers remain
future work.
These limits keep the implementation small and make the native and Web testing
models genuinely consistent. The transport boundary leaves room for another
browser driver later without changing application tests.
Upgrade
Update the application dependency:
fission = { version = "0.11.1", default-features = false, features = ["web"] }
Install the matching CLI for fission test --target web:
cargo install cargo-fission --version 0.11.1 --locked
The complete design and deferred scope are recorded in
docs/rfc-web-testing.md.
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