# Manual Testing Fixtures This folder exists for **React contributors** only. If you use React, you don't need to worry about it. These fixtures verify that the built React distributions are usable in different environments. **They are not running automatically.** (At least not yet. Feel free to contribute to automate them.) Run them when you make changes to how we package React and ReactDOM. ## How to Run First, build React and the fixtures: ``` cd react npm run build node fixtures/packaging/build-all.js ``` Then run a local server, e.g. ``` npx pushstate-server . ``` and open the following URL in your browser: [http://localhost:9000/fixtures/packaging/index.html](http://localhost:9000/fixtures/packaging/index.html) You should see two things: * A number of iframes (corresponding to various builds), with "Hello World" rendered in each iframe. * No errors in the console.