chore: fix N* tests (#33480)

Author: layershifter

packages/fluentui/projects-test/assets/cra/src/index.tsx

@@ -0,0 +1,7 @@
+import * as React from 'react';
+import * as ReactDOM from 'react-dom';
+import App from './App';
+
+const root = document.getElementById('root') as HTMLElement;
+
+ReactDOM.render(<App />, root);

packages/fluentui/projects-test/src/createReactApp.ts

@@ -37,6 +37,11 @@ export async function createReactApp() {
   await addResolutionPathsForProjectPackages(testAppPathRoot);
 
   await shEcho(`yarn add ${packedPackages['@fluentui/react-northstar']}`, testAppPathRoot);
+
+  // Enforce React 17
+  const dependencies = ['@types/react@17', '@types/react-dom@17', 'react@17', 'react-dom@17'].join(' ');
+  await shEcho(`yarn add ${dependencies}`, tempPaths.testApp);
+
   logger(`✔️ Fluent UI packages were added to dependencies`);
 
   logger("STEP 3. Reference Fluent UI components in test project's App.tsx");

packages/fluentui/react-northstar/jest.config.js

@@ -10,6 +10,9 @@ const config = commonConfig({
     // Legacy aliases, they should not be used in new tests
     ...getAliases(),
   },
+  // Keeps Jest from using too much memory as GC gets invokes more often, makes tests slower
+  // https://stackoverflow.com/a/75857711
+  workerIdleMemoryLimit: '1024MB',
 });
 config.setupFilesAfterEnv = [...config.setupFilesAfterEnv, './jest-setup.js'];