API reference

import { test, expect } from "zerospikes";

test is Playwright's, with the zs fixture. The types (MeasureOptions, ScenarioResult, ZeroSpikesOptions…) are exported too.

`zs.measure(name, act, options?)`

Runs act warmup + runs times and checks the median of each metric against its limits. A scenario over them fails the test when it ends, like expect.soft, after one more CPU-profiled run. Returns the ScenarioResult.

Option	Default
`runs`	`5`	Measured runs
`warmup`	`1`	Unmeasured runs first, for JIT and caches
`before`		Before every run, unmeasured: the starting state
`after`		After every run, unmeasured: undo what `act` did
`settleMs`	`300`	Keep recording after `act`, so debounced work counts
`limits`		Fixed limits, such as `{ "frame.max": 50 }`
`profileOnFail`	`true`	CPU-profile a run when a limit is missed. Chromium only

name must be unique within the test.

`zs.cycles(name, cycle, options?)`

Runs warmup cycles, then cycles more, and checks what stayed behind in memory. Chromium only: elsewhere it returns null.

Option	Default
`cycles`	`5`	Measured cycles
`warmup`	`1`	Cycles before the baseline
`limits`		Fixed limits, such as `{ "memory.nodes": 0 }`

`zs.drag(from, to, { steps? })`

Presses at from, moves to to in steps (default 20), one pointermove per frame, and releases.

`zs.frame()`

Resolves on the page's next animation frame.

Config options

Option
`zsIgnoreErrors`	Errors the page may log without failing the scenario. See Limits
`ZS_ALLOW_WORSE=1`	Environment variable: with `-u`, save the limits even when slower

Desktop apps (experimental)

To measure a running Tauri (Windows) or Electron app, import test from zerospikes/app and point the project at the app's DevTools port. page is then the app's window, the same one in every test: put it back in its starting state in beforeEach.

playwright.config.ts

import { defineConfig } from "@playwright/test";
import type { ZeroSpikesAppOptions } from "zerospikes/app";

export default defineConfig<ZeroSpikesAppOptions>({
  workers: 1, // the app has one window
  projects: [{ name: "tauri", use: { zsConnect: "http://127.0.0.1:9222" } }],
  webServer: {
    command: "npx tauri dev",
    env: { WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS: "--remote-debugging-port=9222" },
    url: "http://127.0.0.1:9222/json/version",
    reuseExistingServer: true,
  },
});

Start Electron with --remote-debugging-port=9222. macOS and Linux webviews have no DevTools port: measure the frontend in a browser there. zerospikes compare doesn't work with apps.