chore: Add support for ESM in jest (#2606)

Author: gethinwebster

CONTRIBUTING.md

@@ -162,6 +162,12 @@ npx jest -c jest.motion.config.js src/flashbar
 npx jest -c jest.build-tools.config.js build-tools/stylelint
 ```
 
+Note: when running jest directly you may see errors about `--experimental-vm-modules`, to fix this you can set this NodeJS flag as follows:
+
+```
+export NODE_OPTIONS="$NODE_OPTIONS --experimental-vm-modules"
+```
+
 ### Run visual regression tests
 
 Visual regression tests for the permutation pages are automatically run when opening a pull request in GitHub.

build-tools/tasks/integ.js

@@ -14,7 +14,10 @@ module.exports = task('test:integ', async () => {
   await waitOn({ resources: ['http://localhost:8080'] });
 
   const files = glob.sync('src/**/__integ__/**/*.test.ts');
-  await execa('jest', ['-c', 'jest.integ.config.js', ...files], { stdio: 'inherit' });
+  await execa('jest', ['-c', 'jest.integ.config.js', ...files], {
+    stdio: 'inherit',
+    env: { ...process.env, NODE_OPTIONS: '--experimental-vm-modules' },
+  });
 
   devServer.cancel();
 });

build-tools/tasks/motion.js

@@ -14,7 +14,10 @@ module.exports = task('test:motion', async () => {
   await waitOn({ resources: ['http://localhost:8080'] });
 
   const files = glob.sync('src/**/__motion__/**/*.test.ts');
-  await execa('jest', ['-c', 'jest.motion.config.js', ...files], { stdio: 'inherit' });
+  await execa('jest', ['-c', 'jest.motion.config.js', ...files], {
+    stdio: 'inherit',
+    env: { ...process.env, NODE_OPTIONS: '--experimental-vm-modules' },
+  });
 
   devServer.cancel();
 });