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web-renderer-test

Add explicitly requested web renderer tests or update existing ones for implementation changes.

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less than a month ago
In the catalog since
1 Oct 2026
From
remotion-dev/remotion
Testing & QA
Get it through your agent npx skills add remotion-dev/remotion@web-renderer-test

Skill instructions

Rendered from the published SKILL.md, 77 lines.

Use this skill to update existing web renderer tests when needed for implementation changes. Add new tests only when the user explicitly requests them.

The web renderer is in packages/web-renderer and the test suite is in packages/web-renderer/src/test.

It uses visual snapshot testing using vitest. A test file can for example be executed using:

bunx vitest src/test/video.test.tsx

Example

Each test is powered by a fixture in packages/web-renderer/src/test/fixtures. A fixture looks like this for example:

import {AbsoluteFill} from 'remotion';

const Component: React.FC = () => {
  return (
    <AbsoluteFill
      style={{
        justifyContent: 'center',
        alignItems: 'center',
      }}
    >
      <div
        style={{
          backgroundColor: 'red',
          width: 100,
          height: 100,
          borderRadius: 20,
        }}
      />
    </AbsoluteFill>
  );
};

export const backgroundColor = {
  component: Component,
  id: 'background-color',
  width: 200,
  height: 200,
  fps: 25,
  durationInFrames: 1,
} as const;

The corresponding test looks like this:

import {test} from 'vitest';
import {renderStillOnWeb} from '../render-still-on-web';
import {backgroundColor} from './fixtures/background-color';
import {testImage} from './utils';

test('should render background-color', async () => {
  const blob = await renderStillOnWeb({
    licenseKey: 'free-license',
    composition: backgroundColor,
    frame: 0,
    inputProps: {},
    imageFormat: 'png',
  });

  await testImage({blob, testId: 'background-color'});
});

Adding a new test

  1. Add a new fixture in packages/web-renderer/src/test/fixtures.
  2. Important: Add the fixture to packages/web-renderer/src/test/Root.tsx to add a way to preview it.
  3. Add a new test in packages/web-renderer/src/test.
  4. Run bunx vitest src/test/video.test.tsx to execute the test.
  5. Important: Update packages/docs/docs/client-side-rendering/limitations.mdx to reflect the newly supported property.