build(next): Simplify test setup

babel.config.js

@@ -1,23 +1,13 @@
 module.exports = {
   presets: [
-    [
-      '@babel/preset-env',
-      {
-        targets: {
-          node: 'current',
-        },
-      },
-    ],
+    ['@babel/preset-env', {
+      targets: { node: 'current' },
+    }],
   ],
   plugins: [
-    [
-      'module-resolver',
-      {
-        root: ['./src'],
-        alias: {
-          '@': './src',
-        },
-      },
-    ],
+    ['module-resolver', {
+      root: ['./src'],
+      alias: { '@': './src' },
+    }],
   ],
 };

jest.config.js

@@ -2,5 +2,6 @@ module.exports = async () => {
   return {
     verbose: true,
     testEnvironment: 'jsdom',
+    testPathIgnorePatterns: ['/next/test'],
   };
 };

next/.nvmrc

@@ -0,0 +1 @@
+22.13.1

next/README.md

@@ -9,3 +9,18 @@ This `next/` folder is where the rewriting is happening
 We expect the main `createHeadlessForm()` API to remain the same,
 avoiding any major breaking change.
 This is under active development, more info soon!
+
+## Development
+
+Ensure that you isolate your workspace to the "next" folder only.
+This means:
+1. In your editor, open only the "next" folder.
+1. In your terminal, run commands when you are in the "next" folder only.
+
+Otherwise, your editor may fail to set up linting and type checking,
+while your terminal may fail to resolve paths.
+
+The limitation of this approach is that
+your editor will fail to recognise our git repository here.
+This also means you should turn off the editor's suggestion
+to open git repository at root.

next/babel.config.mjs

@@ -0,0 +1,14 @@
+/**
+ * @type {import('@babel/core').TransformOptions}
+ */
+const options = {
+  presets: [
+    ['@babel/preset-env', { targets: { node: 'current' } }],
+    // Type checking is already done in our build,
+    // so we can use a lightweight preset.
+    // - https://jestjs.io/docs/getting-started#using-typescript
+    '@babel/preset-typescript',
+  ],
+}
+
+export default options

next/jest.config.mjs

@@ -0,0 +1,52 @@
+/**
+ * This next version of JSON Schema Form ("V2")
+ * must be tested against 2 sets ("root") of tests.
+ * Note that "rootDir" is the path to this next version.
+ *
+ * @type {import('jest').Config['roots']}
+ */
+const roots = [
+  // 1. The existing tests from the previous version ("V1")
+  '<rootDir>/../src/tests',
+  // 2. The new tests for this version
+  '<rootDir>/test',
+]
+
+/**
+ * Module aliases to use the same test with different source versions.
+ * To learn more, see "roots" above.
+ *
+ * This is only needed to use V1 tests for V2 source.
+ * as V2 tests are used to test V2 source only.
+ *
+ * @type {import('jest').Config['moduleNameMapper']}
+ */
+const moduleNameMapper = {
+  // We use kebab-case in V2
+  '^@/createHeadlessForm$': '<rootDir>/src/form',
+  '^@/utils$': '<rootDir>/src/utils',
+  // Avoid catch all aliases such as "^@/(.*)$".
+  // Aliases should be added as needed.
+  // If there are many, we will have a compat barrel file.
+}
+
+/**
+ * Some tests are invalid for V2 testing.
+ * For example:
+ * - Buggy behaviours in V1 that are already fixed (and tested) in V2
+ * - Deprecated or removed APIs
+ *
+ * @type {import('jest').Config['testPathIgnorePatterns']}
+ */
+const testPathIgnorePatterns = [
+  // Nothing yet
+]
+
+/** @type {import('jest').Config} */
+const config = {
+  roots,
+  moduleNameMapper,
+  testPathIgnorePatterns,
+}
+
+export default config

next/package.json

@@ -17,6 +17,9 @@
     "form"
   ],
   "main": "index.js",
+  "engines": {
+    "node": "22.13.1"
+  },
   "scripts": {
     "test": "jest",
     "test:watch": "jest --watchAll",
@@ -27,11 +30,11 @@
     "@antfu/eslint-config": "^3.14.0",
     "@babel/core": "^7.23.7",
     "@babel/preset-env": "^7.23.7",
+    "@babel/preset-typescript": "^7.26.0",
+    "@jest/globals": "^29.7.0",
     "babel-jest": "^29.7.0",
     "eslint": "^9.18.0",
     "jest": "^29.7.0",
-    "jest-environment-jsdom": "^29.7.0",
-    "ts-jest": "^29.1.1",
     "tsup": "^8.3.5",
     "typescript": "^5.7.3"
   }