feat(jest): create jest config package for unit testing (#3678)

* feat(jest): create jest config package for unit testing
* chore: housekeeping
* fix: now we need to explicitly allow importing without extension
* fix: recover EditorDriverInterface import
* Apply suggestions from code review
* chore: yarn

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

js-packages/jest-config/.gitignore

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+node_modules
+.DS_Store
+Thumbs.db
+.vscode
+
+# https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions

js-packages/jest-config/LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2022 Stichting Flarum (Flarum Foundation)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

js-packages/jest-config/README.md

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+# Jest config for Flarum
+
+This package provides a [Jest](https://jestjs.io/) config object to run unit & integration tests on Flarum extensions.
+
+## Usage
+
+* Install the package: `yarn add --dev flarum-jest-config`
+* Add `"type": "module"` to your `package.json`
+* Add `"test": "yarn node --experimental-vm-modules $(yarn bin jest)"` to your `package.json` scripts
+* Rename `webpack.config.js` to `webpack.config.cjs`
+* Create a `jest.config.cjs` file with the following content:
+```js
+module.exports = require('flarum-jest-config')();
+```

js-packages/jest-config/index.cjs

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+const path = require('path');
+
+module.exports = (options = {}) => ({
+  testEnvironment: 'jsdom',
+  extensionsToTreatAsEsm: ['.ts', '.tsx'],
+  transform: {
+    '^.+\\.[tj]sx?$': [
+      'babel-jest',
+      require('flarum-webpack-config/babel.config.js'),
+    ],
+    '^.+\\.tsx?$': [
+      'ts-jest',
+      {
+        useESM: true,
+      },
+    ],
+  },
+  preset: 'ts-jest',
+  setupFilesAfterEnv: [path.resolve(__dirname, 'setup-env.js')],
+  moduleDirectories: ['node_modules', 'src'],
+  ...options,
+});

js-packages/jest-config/package.json

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+{
+    "name": "flarum-jest-config",
+    "version": "1.0.0",
+    "description": "Jest config for Flarum.",
+    "main": "index.cjs",
+    "author": "Flarum Team",
+    "license": "MIT",
+    "type": "module",
+    "prettier": "@flarum/prettier-config",
+    "dependencies": {
+        "@types/jest": "^29.2.2",
+        "flat": "^5.0.2",
+        "jest": "^29.3.1",
+        "jest-environment-jsdom": "^29.3.1",
+        "js-yaml": "^4.1.0",
+        "ts-jest": "^29.0.3"
+    },
+    "devDependencies": {
+        "prettier": "^2.4.1"
+    }
+}

js-packages/jest-config/setup-env.js

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+import app from '@flarum/core/src/forum/app';
+import ForumApplication from '@flarum/core/src/forum/ForumApplication';
+import jsYaml from 'js-yaml';
+import fs from 'fs';
+import jquery from 'jquery';
+import m from 'mithril';
+import flatten from 'flat';
+
+// Boot the Flarum app.
+function bootApp() {
+  ForumApplication.prototype.mount = () => {};
+  window.flarum = { extensions: {} };
+  app.load({
+    apiDocument: null,
+    locale: 'en',
+    locales: {},
+    resources: [
+      {
+        type: 'forums',
+        id: '1',
+        attributes: {},
+      },
+    ],
+    session: {
+      userId: 0,
+      csrfToken: 'test',
+    },
+  });
+  app.translator.addTranslations(flatten(jsYaml.load(fs.readFileSync('../locale/core.yml', 'utf8'))));
+  app.bootExtensions(window.flarum.extensions);
+  app.boot();
+}
+
+beforeAll(() => {
+  window.$ = jquery;
+  window.m = m;
+
+  bootApp();
+});