Web Renderer Test Agent Skill

by remotion-dev

Add a test case to the web renderer

493 tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

55471

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/remotion-dev/remotion --skill web-renderer-test

The instruction itself

2 sections, as written by the author

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

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

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How to use it

Copy the folder

Take remotion-dev/web-renderer-test from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.