Merge pull request #490 from ckeditor/migrate-to-esm

Internal: Migrate from webpack and Karma to Vite and Vitest. See ckeditor/ckeditor5#16616.

Internal: Fix test coverage which only covered a small portion of the codebase.

MINOR BREAKING CHANGE: Migrate to ESM. Related to ckeditor/ckeditor5#16616.

.circleci/config.yml

@@ -72,7 +72,7 @@ jobs:
           command: yarn run build
       - run:
           name: Run unit tests
-          command: yarn run coverage
+          command: yarn run test
       - run:
           name: Verify the code coverage
           command: |

.eslintrc.js → .eslintrc.cjs

@@ -26,6 +26,7 @@ module.exports = {
 	},
 	'rules': {
 		'react/prop-types': 'off',
+		'react/no-deprecated': 'off',
 		'no-console': 'off',
 		'no-trailing-spaces': 'error',
 		'ckeditor5-rules/allow-imports-only-from-main-package-entry-point': 'off',

README.md

@@ -26,28 +26,33 @@ npm install
 
 You can also use [Yarn](https://yarnpkg.com/).
 
+### Running the development server
+
+To manually test the editor integration with different versions of React, you can start the development server using one of the commands below:
+
+```bash
+npm run dev:16 # Open the demo projects using React 16.
+npm run dev:18 # Open the demo projects using React 18.
+npm run dev:19 # Open the demo projects using React 19.
+```
+
 ### Executing tests
 
-Before starting tests execution, you need to build the package. You can use `npm run build` in order to build the production-ready version
-or `npm run develop` which produces a development version with attached watcher for all sources files.
+To test the editor integration against a set of automated tests, run the following command:
 
 ```bash
-npm run test -- [additional options]
-# or
-npm t -- [additional options]
+npm run test
 ```
 
-The command accepts the following options:
+If you want to run the tests in watch mode, use the following command:
 
-* `--coverage` (`-c`) – Whether to generate the code coverage.
-* `--source-map` (`-s`) – Whether to attach the source maps.
-* `--watch` (`-w`) – Whether to watch test files.
-* `--reporter` (`-r`) – Reporter for Karma (default: `mocha`, can be changed to `dots`).
-* `--browsers` (`-b`) – Browsers that will be used to run tests (default: `Chrome`, available: `Firefox`).
+```bash
+npm run test:watch
+```
 
 ### Building the package
 
-Build a minified version of the package that is ready to publish:
+To build the package that is ready to publish, use the following command:
 
 ```bash
 npm run build