Add document explaing how to make changes and view them locally

README.md

@@ -32,33 +32,7 @@ If the `fractal watch` task fails, remove the `dist` directory and try running `
 
 ## Previewing Changes
 
-As you make changes to this design system, you'll likely want to see how your changes look in a consuming app, such as the `vets-website` app. Follow these instructions to see your changes locally in the Vets Website.
-
-### 1. Build the components:
-
-Run: `npm run export-components`
-
-> Builds all JSX files in `src/components` and all js files in `src/helpers` and adds them to the `dist/formation` folder.
-
-> `dist/formation` is the root directory of the NPM module.
-
-### 2. Preview the components locally with Yalc:
-
-[yalc](https://github.com/whitecolor/yalc) is recommended for testing modules locally.
-
-* Install Yalc globally if you don't have it: `yarn global add yalc`
-
-* With Yalc installed, run: `npm run test-publish`
-
-> Copies `package.json` to the `dist/formation` directory and publishes the exported components to the local yalc directory as a `@department-of-veterans-affairs/formation` module.
-
-* In the `vets-website` project, run `yalc link @department-of-veterans-affairs/formation` and subsequently `yalc update`
-
-> Installs the locally published version of `formation` to the Vets Website's `node_modules` folder, making it available for importing and testing locally.
-
-* With each new change you make to the design system code, you'll need to re-run `yalc update` to see the changes reflected in your locally-running version of `vets-website`.
-
-> See [yalc documentation](https://www.npmjs.com/package/yalc#usage) for advanced usage such as [automatic updating on publish](https://www.npmjs.com/package/yalc#pushing-updates-automatically-to-all-installations)
+As you make changes to this design system, you'll likely want to see how your changes look in a consuming app, such as the `vets-website` app. [Check out these instructions on how to do so](./previewing-changes.md).
 
 ## Publishing Module to NPM
 

previewing-changes.md

@@ -0,0 +1,37 @@
+# Making changes to design-system/formation and previewing them
+As you work in the `design-system` repo, you'll want to preview how your changes look in an app that uses `formation`. To do this, we use [Yalc](https://github.com/whitecolor/yalc) to publish `formation` locally, rather than to NPM, and tell the consuming app to install that local version of `formation`. In these examples, for the sake of simplicity, we'll assume you are using `vets-website` as the consuming app. But instructions should be similar for any app using `formation`.
+
+## Getting set up
+First, install Yalc globally if you haven't already: `yarn global add yalc`.
+
+While in the `design-system` app:
+1. Run `npm run export-components` to build the module into the `dist/formation/` dir.
+2. Run `npm run test-publish` to publish the module to your local `~/.yalc` dir.
+
+Then in the consuming app (`vets-website`):
+1. Run `yalc link @department-of-veterans-affairs/formation` to tell the `vets-website` project to use the local version of `formation` instead of the one installed via NPM (i.e. the `formation` dir in `node_modules` will now be a symlink to a dir in `~/.yalc`).
+2. Fire up the website locally with `yarn watch`.
+
+The locally running project, at `localhost:3001`, will now be using the locally published version of `formation`.
+
+## The change-publish-preview loop
+With each change you make to the `design-system`, you'll need to rebuild the module, republish the `formation` module to `~/.yalc`, and also tell the consuming app to use the new version.
+
+While in the `design-system` app:
+1. Make some changes to the code.
+2. Build the module and publish it locally to `~/.yalc` by running `npm run export-components` followed by `npm run test-publish`.
+
+Then in the consuming app:
+1. Run `yalc update` to bring in the latest version of `formation`.
+2. If you are using `vets-website` as your consuming app and it is already running, it should notice the changes and rebuild. If not, restart the app locally.
+3. After rebuilding completes, your changes will now be visible locally at `localhost:3001`.
+
+## Tearing down the local testing setup
+When you are done testing `formation` locally, you'll want to get your consuming app back to normal; that is, tell it to stop using the version of `formation` published to `~/.yalc` and go back to using the version from NPM.
+
+In the consuming app:
+1. run `yalc remove @department-of-veterans-affairs/formation` to remove the link from the consuming app's `node_modules` dir to the local version of `formation`.
+2. **NOTE:** There seems to be [an issue](https://github.com/whitecolor/yalc/issues/37) with Yalc not cleaning up after itself properly, so you'll have to also run `unlink node_modules/@department-of-veterans-affairs/formation`
+3. Run `yarn install --check-files` to reinstall `formation` from NPM. (If you're curious about why you need to `--check-files` flag, [check out this issue](https://github.com/yarnpkg/yarn/issues/2240).)
+
+Your consuming app should be back to normal!