test: verify importing js exports works before versioning

.github/workflows/check.yml

@@ -1,17 +1,25 @@
-name: Build and dry-run publish to npmjs
-on: push
+name: Build and test package
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+concurrency:
+  group: ${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}
 jobs:
   build:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
         with:
-          node-version: '18.x'
-          registry-url: 'https://registry.npmjs.org'
+          node-version-file: ".nvmrc"
+          registry-url: "https://registry.npmjs.org"
+          cache: "npm"
       - run: npm install -g npm
       - run: npm ci
       # Build to verify
       - run: npm run build
-      # Dry-run a publish to log package contents
-      - run: npm publish --dry-run
+      # Verify built artefacts
+      - run: npm run test

.nvmrc

@@ -0,0 +1 @@
+v20.8.0

README.md

@@ -16,7 +16,8 @@ First clone `@nrk/core-icons` and install its dependencies:
 ```bash
 git clone git@github.com:nrkno/core-icons.git
 cd core-icons
-npm install
+# Install dependencies according to package-lock-file
+npm ci
 npm start # Your browser will open documentation with hot reloading
 ```
 
@@ -30,8 +31,34 @@ See [Conventional Commits](https://conventionalcommits.org) for commit guideline
 git checkout -b feature/my-changes
 # Update the source code
 npm run build
+# Test to ensure integrity
+npm run test
 git commit -am "<type>[optional scope]: <desciption>"
 git push --set-upstream origin feature/my-changes
 # Make a PR to the master branch,
 # Assign a developer to review your code
 ```
+
+## Testing
+
+We use [Testpack-cli](https://github.com/qwertie/testpack) to ensure published exports work as intended. In short it does the following:
+
+- Runs `npm pack` and moves the generated archive to a sibling test folder `nrk-core-icons-testpack` (which is created if not present) to core-icons
+- npm-installs React in the testpack-folder
+- Copies the `test`-folder to the testpack-folder
+- Runs the `testpack-script` in the testpack-folder
+- Cleans up
+
+We use [arethetypeswring/cli](https://github.com/arethetypeswrong/arethetypeswrong.github.io/tree/main/packages/cli) to verify that our type declarations are available for consumers.
+
+- We purposefully ignore the [false-cjs](https://github.com/arethetypeswrong/arethetypeswrong.github.io/blob/main/docs/problems/FalseCJS.md)-rule as our types are generated from [@nrk/svg-to-js](https://github.com/nrkno/svg-to-js) which only gives us cjs types. We chose not to duplicate the `d.ts`-file to a `d.mts` to solve this error as it could lead to unexpected behavior for consumers.
+
+## nvm
+
+Uses [Node Version Manager](https://github.com/nvm-sh/nvm/blob/master/README.md#intro) (nvm) to organize node version
+
+nvm config is saved in `.nvmrc`, set appropriate node version using:
+
+```shell
+nvm use
+```