Migrate from Jest to Vitest (#34454)

vite.config.mts

@@ -0,0 +1,58 @@
+/// <reference types="vitest" />
+
+import fs from 'fs';
+import path from 'path';
+
+import react from '@vitejs/plugin-react';
+import RailsPlugin from 'vite-plugin-rails';
+import svgr from 'vite-plugin-svgr';
+import { defineConfig, configDefaults } from 'vitest/config';
+
+const sourceCodeDir = 'app/javascript';
+const items = fs.readdirSync(sourceCodeDir);
+const directories = items.filter((item) =>
+  fs.lstatSync(path.join(sourceCodeDir, item)).isDirectory(),
+);
+const aliasesFromJavascriptRoot: Record<string, string> = {};
+directories.forEach((directory) => {
+  aliasesFromJavascriptRoot[directory] = path.resolve(
+    __dirname,
+    sourceCodeDir,
+    directory,
+  );
+});
+
+export default defineConfig({
+  resolve: {
+    alias: {
+      ...aliasesFromJavascriptRoot,
+    },
+  },
+  plugins: [
+    RailsPlugin(),
+    react({
+      include: ['**/*.jsx', '**/*.tsx'],
+      babel: {
+        plugins: ['formatjs', 'preval', 'transform-react-remove-prop-types'],
+      },
+    }),
+    svgr(),
+  ],
+  test: {
+    environment: 'jsdom',
+    include: [
+      ...configDefaults.include,
+      '**/__tests__/**/*.{js,mjs,cjs,ts,mts,cts,jsx,tsx}',
+    ],
+    exclude: [
+      ...configDefaults.exclude,
+      '**/node_modules/**',
+      'vendor/**',
+      'config/**',
+      'log/**',
+      'public/**',
+      'tmp/**',
+    ],
+    globals: true,
+  },
+});