Files
webstudio/scripts/visual-regression/capture.ts
T
Oleg Isonen db2d092268 ci: replace Lost Pixel with self-hosted visual regression (#6086)
## Summary

Replace the defunct Lost Pixel service and the interim Chromatic
workflow with a fast, self-hosted visual comparison pipeline.

The workflow indexes the existing CSF stories without building
Storybook, builds and serves a lightweight browser app with Vite,
renders the merge base and current revision through Webstudio's shared
browser tooling, and compares screenshots with Webstudio's pixel-diff
and OCR engine. It uses GitHub Actions cache and artifacts only—no R2
bucket or external visual-testing service.

Closes #6064

## Implementation

- [x] Remove the Lost Pixel workflow, configuration, acknowledgement,
and global two-second wait.
- [x] Remove the interim Chromatic workflow and settings.
- [x] Extract source-agnostic capture, diff, OCR, audit, cache, and
report tooling into `@webstudio-is/vision`; rename the
Webstudio-specific preview boundary to
`@webstudio-is/project-build/preview`.
- [x] Expose the reusable browser capture session through the shared
vision boundary.
- [x] Make OCR and diff-artifact generation conditional on detected
pixel changes.
- [x] Render existing CSF stories through a typed, lightweight browser
harness built with Vite.
- [x] Replace the embedded HTML and handwritten HTTP/MIME server with a
real HTML entry, Vite production build, and Vite preview server; isolate
declarative build configuration in `story-build.ts`.
- [x] Apply Storybook preview annotations, decorators, global CSS,
backgrounds, and story metadata.
- [x] Store story scopes as shared data and load each revision's own
configuration.
- [x] Discover changed, added, and removed stories from both revisions.
- [x] Populate private story sources symmetrically in the baseline
worktree.
- [x] Isolate every story with a fresh React root and deterministic
time, randomness, intervals, focus, animation, and layout readiness.
- [x] Preserve story-owned visual options for masking, settling, and
interval control.
- [x] Reuse Vite preview servers, one Chromium process, grouped browser
pages, production bundles, and a bounded CPU worker pool for image
comparison.
- [x] Recheck initial pixel differences with serial captures, then
recapture persistent baseline/current pairs on the same browser page so
renderer variance cannot create false failures.
- [x] Report individual story render failures without discarding
successful captures.
- [x] Enforce a 0.1 per-pixel threshold and 0.001% total mismatch
tolerance.
- [x] Run OCR only for changed comparisons and include text-change
evidence.
- [x] Move the generic report model, writer, static viewer, and opener
into the shared Vision package for reuse by CI and future CLI
comparisons.
- [x] Bundle report HTML, styling, and browser behavior as static Vision
assets without runtime source-file lookups.
- [x] Copy external screenshot inputs into self-contained report
artifacts for CLI reuse.
- [x] Handle cached removed-only comparisons without rendering the
removed story on the current server.
- [x] Support focused local reproduction and opening the report with one
command.
- [x] Pin CI to the lockfile's Playwright Chromium, cache complete
revision screenshots with matching restore/save paths and automatically
derived runtime invalidation, and render both revisions on a miss.
- [x] Keep cache archives bounded to one revision instead of
accumulating the cache history.
- [x] Run the complete visual suite in one CI job and upload one report
as a 14-day artifact.
- [x] Fail PR checks on visual differences, empty runs, missing
screenshots, missing or empty report artifacts, and infrastructure
failures.
- [x] Rerun fork checks when `safe-to-deploy` is added.
- [x] Allow reviewed visual-only differences through
`visual-change-approved` and invalidate approval after new commits.
- [x] Keep capture, pixel diff, OCR, and report generation
source-agnostic for future draft-versus-published project comparisons.
- [x] Use Vite for the complete story HTML, module, asset,
production-build, and preview-server lifecycle; inline the selected
stories and skip ineffective tree-shaking to keep the cached run under
one minute.
- [x] Review Builder product documentation impact: no user-facing
Builder documentation is affected; contributor usage is documented in
`scripts/visual-regression/README.md`.
- [x] Review fixture impact: no fixture inputs or generated fixture
outputs are affected.

## Verification

- [x] Project-build Vision tests, including the reusable report test,
and entrypoint contract tests pass.
- [x] CLI screenshot, preview, and browser-session tests pass.
- [x] Project-build, CLI, Builder, design-system, and visual-runner
typechecks pass.
- [x] Visual runner tests pass (10), and the complete Vision package
passes (79), including demonstrated fail-before/pass-after coverage.
- [x] Full Storybook production build passes.
- [x] Full local Vite run completes all 238 stories in 69.9s cold and
50.3s with a cached baseline plus two same-page serial verifications,
with zero differences; identical-image comparison remains sub-second.
- [x] The report writer passes a bundled-output smoke test and
materializes external screenshot assets.
- [x] The generated report validates all 238 entries and referenced
images.
- [x] Hosted cached-baseline comparison completes all 238 stories in
52.9s with zero differences; the cache-miss fallback completes in
101.3s.
- [x] Cache-miss fallback renders both Git revisions on demand.
- [x] Visual differences produce baseline, current, diff, OCR, JSON, and
HTML evidence and fail without approval.
- [x] Hosted single-job visual workflow restores both the pinned browser
and baseline cache, validates all 238 public and private stories with
zero differences, and uploads the report.
- [x] The final Vite production build renders all 238 stories without
dependency invalidation or duplicate React runtimes, and restores
`NODE_ENV` so cached serial fallback installs the baseline's dev
dependencies.
- [x] Root lint, package-boundary validation, and relevant formatting
checks pass.
- [x] Workflow YAML parses successfully.
- [x] `git diff --check`, staged-diff review, and final worktree review
pass.

## Usage

Run the complete local comparison and open the visual report:

```sh
pnpm visual-regression:ui
```

Focus one component while iterating:

```sh
pnpm visual-regression:ui -- --grep "Design system/Button"
```

Reopen the latest report without rerunning:

```sh
pnpm visual-regression:report
```

The CI report is available as the `visual-regression-report` artifact.

## Tradeoffs

- Baseline screenshots are a disposable acceleration cache, not source
of truth. A missing or invalid cache renders the merge base directly
from Git.
- GitHub artifact storage provides downloadable one-click reports;
permanently hosted browser links would require another hosting surface.
- OCR runs after pixel triage because invoking Tesseract for every
unchanged story would make the common path unnecessarily slow.
- Vite production builds add Rollup's module graph and HTML/asset
pipeline. The runner emits one bundle because every selected story is
rendered, and skips tree-shaking because it removed little while
increasing build time.
- The verified local path is 50.3s cached and 69.9s cold. The hosted
path is 52.9s cached and 101.3s cold. A new browser/runtime cache must
render its baseline once; the pinned browser keeps later runners on the
reusable path.
- The complete suite stays in one Actions job; browser-page concurrency
is internal and bounded.
2026-08-12 10:55:52 +02:00

165 lines
4.3 KiB
TypeScript

import path from "node:path";
import type { BrowserScreenshotOptions } from "@webstudio-is/vision/browser";
import {
captureVisualEntries,
type VisualCaptureSession,
} from "@webstudio-is/vision/capture";
import { visualRegressionConfig } from "./config";
import type { VisualStoryEntry } from "./manifest";
const onBatchFailure = (error: unknown, count: number) => {
console.warn(
`Visual capture failed for ${count} stories; isolating the failure.`,
error
);
};
export const getInitialCaptureTarget = ({
baselineEntries,
currentEntries,
hasCachedBaseline,
}: {
baselineEntries: readonly VisualStoryEntry[];
currentEntries: readonly VisualStoryEntry[];
hasCachedBaseline: boolean;
}) => {
const currentEntry = currentEntries[0];
if (currentEntry !== undefined) {
return { entry: currentEntry, target: "current" as const };
}
const baselineEntry = baselineEntries[0];
if (hasCachedBaseline === false && baselineEntry !== undefined) {
return { entry: baselineEntry, target: "baseline" as const };
}
};
export const getStoryCaptureOptions = ({
browserPath,
entry,
output,
port,
}: {
browserPath: string;
entry: VisualStoryEntry;
output: string;
port: number;
}): BrowserScreenshotOptions => ({
browserPath,
output,
...visualRegressionConfig.capture.viewport,
fullPage: true,
includeElementGeometry: false,
url: new URL("/", `http://127.0.0.1:${port}`).href,
uid: process.getuid?.(),
disableSandbox: process.env.GITHUB_ACTIONS === "true",
waitUntil: "load",
prepareExpression: `window.renderVisualStory(${JSON.stringify({
file: entry.file,
exportName: entry.exportName,
title: entry.title,
})}).catch(window.showVisualError)`,
waitForSelector: "#visual-ready, #visual-error",
failForSelector: "#visual-error",
waitForTimeout: 0,
finalizeExpression: "window.finishVisualStory()",
timeout: visualRegressionConfig.capture.timeout,
format: "png",
scale: 1,
});
export const captureStories = async ({
assetDirectory,
browserPath,
concurrency,
entries,
port,
target,
session,
}: {
assetDirectory: string;
browserPath: string;
concurrency: number;
entries: readonly VisualStoryEntry[];
port: number;
target: "baseline" | "current";
session: VisualCaptureSession | undefined;
}) =>
captureVisualEntries({
captures: entries.map((entry) => {
const output = path.join(assetDirectory, entry.id, `${target}.png`);
return {
id: entry.id,
options: getStoryCaptureOptions({ browserPath, entry, output, port }),
};
}),
concurrency,
session,
onBatchFailure,
});
export const captureStoryPairs = async ({
assetDirectory,
browserPath,
pairs,
baselinePort,
currentPort,
session,
}: {
assetDirectory: string;
browserPath: string;
pairs: readonly {
baseline: VisualStoryEntry;
current: VisualStoryEntry;
}[];
baselinePort: number;
currentPort: number;
session: VisualCaptureSession | undefined;
}) => {
const targets = new Map<
string,
{ id: string; target: "baseline" | "current" }
>();
const captures = pairs.flatMap(({ baseline, current }) =>
[
{ entry: current, port: currentPort, target: "current" as const },
{ entry: baseline, port: baselinePort, target: "baseline" as const },
].map(({ entry, port, target }) => {
const captureId = `${target}:${entry.id}`;
const output = path.join(assetDirectory, entry.id, `${target}.png`);
targets.set(captureId, { id: entry.id, target });
return {
id: captureId,
options: getStoryCaptureOptions({ browserPath, entry, output, port }),
};
})
);
const result = await captureVisualEntries({
captures,
concurrency: 1,
session,
onBatchFailure,
});
const capturesByTarget = {
baseline: {
paths: new Map<string, string>(),
errors: new Map<string, string>(),
},
current: {
paths: new Map<string, string>(),
errors: new Map<string, string>(),
},
};
for (const [captureId, { id, target }] of targets) {
const capture = capturesByTarget[target];
const capturePath = result.paths.get(captureId);
if (capturePath !== undefined) {
capture.paths.set(id, capturePath);
}
const error = result.errors.get(captureId);
if (error !== undefined) {
capture.errors.set(id, error);
}
}
return capturesByTarget;
};