Testing

Because rendering produces a value, components test headlessly — no DOM, no browser, no emulator. kinetica-test drives components the way a user would and asserts on trees.

The harness

val root = KineticaTest.render {
    var count by state { 0 }
    column {
        text("Count: $count")
        button(
            onClick = event { count += 1 },
            semantics = Semantics(role = Role.Button, testTag = "increment"),
        ) { text("Increment") }
    }
}

root.click(hasTestTag("increment"))
root.assertHtmlSnapshot("""<column>Count: 1<button enabled="true">Increment</button></column>""")

Interactions dispatch through the real event pipeline: click(matcher), input(matcher, value), node(matcher).submit(). Matchers compose: hasTestTag("save") and hasRole(Role.Button), hasText("Count: 1"), hasLabel("Save document").

Async: the suspend harness

val root = KineticaTest.renderSuspend {
    loadingBoundary(fallback = { text("Loading") }) {
        val value = resource(ProfileKey) { api.load() }.read()
        text(value)
    }
}

withTimeout(2_000) { root.awaitIdle() }     // drains effects and resource loads
root.node(hasText("Loaded"))                // now ready
root.advanceTimeBy(125)                     // virtual time for timers/animations

awaitIdle() settles launched effects, watches and resources; advanceTimeBy drives the runtime's virtual clock — deterministic tests for motion and timeouts, no real sleeping.

Snapshots

Two canonical serializations, both stable and diff-friendly:

root.treeSnapshot()      // pretty JSON of the Node tree
root.htmlSnapshot()      // the toSafeHtml() form
root.assertTreeSnapshot(expected)
root.assertHtmlSnapshot(expected)

The journal in tests

Every test root records the full execution journal — assert on causality itself:

val commit = root.journal().last { it.kind == JournalKind.RenderCommitted }
assertEquals("cell write", commit.attributes["cause"])

Browser-level verification

For renderer behavior that only exists in a real DOM (focus, patched-element identity, input cursors), the repo runs Playwright against browser-executed self-tests (samples/browser-tests, driven by scripts/verify-browser.mjs). Component logic belongs in headless tests; browser tests cover the renderer contract.

./kotlin test -m my-module --platform jvm     # headless component tests
node scripts/verify-browser.mjs               # browser renderer verification