Running CLI with local modifications

React Native is distributed as two npm packages, react-native-cli and react-native. The first one is a lightweight package that should be installed globally (npm install -g react-native-cli), while the second one contains the actual React Native framework code and is installed locally into your project when you run react-native init.

Because react-native init calls npm install react-native, simply linking your local github clone into npm is not enough to test local changes.

Introducing Sinopia

Sinopia is an npm registry that runs on your local machine and allows you to publish packages to it. Everything else is proxied from npmjs.com. We'll set up sinopia for React Native CLI development. First, install it with:

$ npm install -g sinopia

Now you can run sinopia by simply doing:

$ sinopia

Running it for the first time creates a default config file. Open ~/.config/sinopia/config.yaml and configure it like this (note the max_body_size):

storage: ./storage

auth:
  htpasswd:
    file: ./htpasswd

uplinks:
  npmjs:
    url: https://registry.npmjs.org/

packages:
  'react-native':
    allow_access: $all
    allow_publish: $all

  'react-native-cli':
    allow_access: $all
    allow_publish: $all

  '**':
    allow_access: $all
    proxy: npmjs

  '*':
    allow_access: $all
    proxy: npmjs

logs:
  - {type: stdout, format: pretty, level: http}

max_body_size: '50mb'

Remember to restart sinopia afterwards.

Publishing to sinopia

Now we need to publish the two React Native packages to our local registry. To do this, we configure npm to use the new registry, unpublish any existing packages and then publish the new ones:

react-native$ npm set registry http://localhost:4873/
react-native$ npm adduser --registry http://localhost:4873/
# Check that it worked:
react-native$ npm config list
react-native$ npm unpublish --force
react-native$ npm publish
react-native$ cd react-native-cli/
react-native-cli$ npm unpublish --force
react-native-cli$ npm publish

Running the local CLI

Now that the packages are installed in sinopia, you can install the new react-native-cli package globally and when you use react-native init, it will install the new react-native package as well:

$ npm uninstall -g react-native-cli
$ npm install -g react-native-cli
$ react-native init AwesomeApp

Testing changes

Most of the CLI code is covered by jest tests, which you can run with:

$ npm test

Project generation is also covered by e2e tests, which you can run with:

$ ./scripts/e2e-test.sh

These tests actually create a very similar setup to what is described above (using sinopia) and they also run iOS-specific tests, so you will need to run this on OSX and have xctool installed.

Both of these types of tests also run on Travis both continuously and on pull requests.

Clean up

To unset the npm registry, do:

$ npm set registry https://registry.npmjs.org/
# Check that it worked:
$ npm config list

Troubleshooting

Sinopia crashes with "Module version mismatch"

This usually happens when you install a package using one version of Node and then change to a different version. This can happen when you update Node, or switch to a different version with nvm. Do:

$ npm uninstall -g sinopia
$ npm install -g sinopia

After upgrading to Node 4 you might also need to reinstall npm. What worked for me was:

$ npm uninstall -g npm
$ nvm install npm

See the nvm guide for more info.

Alternative workflow

If you don't want to install Sinopia you could still test changes done on the cli by creating a sample project and installing your checkout of react-native on that project instead of downloading it from npm. The simplest way to do this is by:

$ npm init AwesomeProject
$ cd AwesomeProject
$ npm install $REACT_NATIVE_GITHUB

Note that REACT_NATIVE_GITHUB should point to the directory where you have a checkout.

Also, if the changes you're making get triggered when running react-native init AwesomeProject you will want to tweak the global installed react-native-cli library to install the local checkout instead of downloading the module from npm. To do so just change this line and refer the local checkout instead.