@crvy/strybk

Generator-first Playwright screenshot testing for Storybook.

Installation

npm install --save-dev @crvy/strybk

CLI

Generate screenshot specs from a Storybook index:

crvy-strybk generate --config ./strybk.config.ts

Use --dry-run to compute outputs without writing files:

crvy-strybk generate --config ./strybk.config.ts --dry-run

The config module should export a StrybkConfig object, typically as the default export from defineConfig(...).

Minimal strybk.config.ts:

import { defineConfig } from "@crvy/strybk";

export default defineConfig({
  storybookUrl: "http://localhost:6006",
  storyGlobs: ["src/**/*.stories.tsx"],
  resolveSpecPath: ({ storyFilePath }) => storyFilePath.replace(/\.stories\.tsx$/, ".spec.ts"),
});

Generated tests

Each generated spec renders a Playwright test per story. At runtime, parameters.creevey (read from the running Storybook, merged across global / kind / story levels) drives capture and skip behavior — no Storybook addon required:

Generated suites import describe, test, expect, switchStory from @crvy/strybk and nest one describe per title segment — Components/Button becomes describe('Components') > describe('Button') — so the Playwright HTML reporter shows a collapsible tree. Snapshot filenames are unaffected. Note that --grep patterns containing / no longer match (Playwright greps the space-joined title path); grep by a single segment instead, e.g. --grep CommentLine.

• captureElement: '<selector>' — captures page.locator('<selector>').
• captureElement: null (or unset) — captures the viewport.
• skip: { '<reason>': { in, kinds, stories } } — marks the test skipped with <reason>. Note: in matches the Playwright project name (not the browser engine), so with the default project name chromium, a rule like { in: 'chrome' } won't match — name your Playwright projects to line up with your in: rules, or scope rules via kinds/stories.
• ignoreElements: '<selector>' | ['<selector>'] — masks those elements via toHaveScreenshot({ mask }).
• delay: <ms> — waits <ms> milliseconds after switching to the story before resolving the capture target. Non-positive or non-numeric values are treated as 0.

Example:

// stories/MyModal.stories.tsx
export default {
  title: "MyModal",
  parameters: { creevey: { captureElement: "#storybook-root" } },
};

export const Default = {
  parameters: { creevey: { ignoreElements: ".timestamp" } },
};

Prerequisites for running specs: @playwright/test (peer dependency) and browser binaries (npx playwright install). The crvy-strybk generate command itself needs neither — only a running Storybook to fetch index.json. To run the same specs under Vitest Browser Mode instead, see Vitest Browser Mode: vitest + @vitest/browser-playwright (optional peers) and a built Storybook.

Vitest Browser Mode

The same generated spec files run under either runner — no generator flag, no config change. playwright test and vitest run both discover *.spec.ts by default; the @crvy/strybk import resolves to the Playwright runtime in Node and to the Vitest runtime inside Vitest Browser Mode (via the browser package export condition). Pick a runner by choosing which command you execute.

Requirements and wiring:

1. Build your Storybook. The Vitest path serves storybook build output through a proxy; dev-mode Storybook servers are not supported (their absolute vite dev asset URLs cannot resolve under the proxy). The dev loop stays on Playwright.

   npx storybook build
   npx http-server storybook-static -p 6007   # or any static server

2. Wire the proxy plugin in vitest.config.ts. It mounts the Storybook origin under a reserved prefix (default /storybook, configurable) on the Vitest dev server so the embedded preview iframe is same-origin:

   import { strybkStorybookProxy } from "@crvy/strybk/vite";
   import { playwright } from "@vitest/browser-playwright";
   import { defineConfig } from "vitest/config";
   
   export default defineConfig({
     plugins: [strybkStorybookProxy({ target: "http://127.0.0.1:6007" })],
     test: {
       browser: {
         enabled: true,
         provider: playwright(),
         headless: true,
         instances: [{ browser: "chromium", viewport: { width: 1280, height: 720 } }],
       },
       provide: { strybkBrowser: "chromium" },
     },
   });

   Reserve the prefix: requests under /storybook are proxied to the target, so keep it free of your own routes (or pass a different prefix).

3. Provide the browser identity (strybkBrowser) so skip in: rules match like Playwright project names — the default is chromium. Optionally provide strybkGlobals (applied to the preview through the Storybook channel before capture), mirroring the Playwright path's storybookGlobals project metadata.

Notes:

• Baselines live under __screenshots__/ next to the specs. The first run writes the baseline and fails ("No existing reference screenshot found; a new one was created"); seed baselines without failing with vitest run --update. Each runner keeps its own baseline tree — do not share them across runners.
• Capture parity is pinned by the runtime: CSS-pixel scale (scale: "css"), Playwright's default comparator threshold (0.2), and animations disabled. One caveat: keep the instance viewport within the headless browser window — Vitest scales its tester iframe when the viewport does not fit, which shrinks captures (this affects Vitest's own page.screenshot() identically).
• Generated specs import describe from the package. Regenerate to adopt the new shape; un-regenerated specs that call test.describe keep collecting through the runtime bridge on every supported vitest 4.x.
• Tested against vitest 4.0.18 and 4.1.11 (peer range vitest >=4 <5).

Portable interaction subset for manual regions (sharedPage.locator(...)):

Portable API	Behavior
click, dblClick, hover, fill, clear	Delegates to the Vitest locator; options (for example hover({ position })) pass through to the provider
press	Accepts Playwright key chords (Control+A) and maps them to testing-library keyboard syntax
type	Types text into the element (Vitest's userEvent.type)
nth(i), first(), last(), locator(selector)	Re-wrapped locators; nested locator() scopes inside the parent, and masks/capture targets accept them
dragTo(target, options)	Maps to Vitest's dropTo; accepts Playwright-style sourcePosition/targetPosition, force, timeout
sharedPage.waitForTimeout(ms)	Waits before capture; backs the generated delay support

Playwright-only APIs — manual regions using them stay single-runner:

• sharedPage.mouse
• Web-first element assertions (expect(locator).toHaveText(...) and friends)
• waitForLoadState and the rest of the Playwright Page/Locator surface

For pointer positioning, the portable replacement for sharedPage.mouse is sharedPage.locator('body').hover({ position: { x, y } }).

Upgrading from 0.0.x

metadataExtractors has been removed. skip and captureElement now resolve automatically at runtime — remove any metadataExtractors: ["creevey"] line from your strybk.config.ts and re-run crvy-strybk generate. Skipped stories now appear as skipped in Playwright reports rather than being omitted from the spec file.

Changelog

Preview the next changelog entry:

bun run changelog:preview

Regenerate the full changelog from git history:

bun run changelog:generate

Local Linking

Build the package:

bun run build

Register this package for local linking:

cd /path/to/strybk
bun link

Link it into the consumer project:

cd /path/to/consumer-project
bun link @crvy/strybk

If you want to persist the link in the consumer's manifest, Bun supports a link: dependency entry:

{
  "dependencies": {
    "@crvy/strybk": "link:strybk"
  }
}

Development

Install dependencies with Bun:

bun install

Common local commands:

bun run lint
bun run typecheck
bun run test:bun
bun run build
bun run check