feat(client): Persist editor open tabs (#59103)

Co-authored-by: sembauke <semboot699@gmail.com>

e2e/multifile-editor.spec.ts

@@ -1,6 +1,8 @@
 import { test, expect } from '@playwright/test';
 
-import { getEditors } from './utils/editor';
+import { clearEditor, focusEditor, getEditors } from './utils/editor';
+import solution from './fixtures/learn-basic-css-by-building-a-cafe-menu-15.json';
+import { isMacOS } from './utils/user-agent';
 
 test.beforeEach(async ({ page }) => {
   await page.goto(
@@ -72,4 +74,54 @@ test.describe('MultifileEditor Component', () => {
 
     expect(await editorPane.getAttribute('style')).toBe(newStyle);
   });
+
+  test('Multiple open editors should remain open on moving to next challenge', async ({
+    page,
+    isMobile,
+    browserName,
+    context
+  }) => {
+    test.skip(
+      browserName !== 'chromium',
+      'Only chromium allows us to use the clipboard API.'
+    );
+    await context.grantPermissions(['clipboard-read', 'clipboard-write']);
+
+    await focusEditor({ page, isMobile });
+    await clearEditor({ page, browserName });
+
+    await page.evaluate(
+      async solution => await navigator.clipboard.writeText(solution.content),
+      solution
+    );
+
+    if (isMacOS) {
+      await page.keyboard.press('Meta+v');
+    } else {
+      await page.keyboard.press('Control+v');
+    }
+
+    const stylesEditor = page.getByRole('button', {
+      name: 'styles.css Editor'
+    });
+    await stylesEditor.click();
+    const editorsCurrentPage = getEditors(page);
+    await expect(editorsCurrentPage).toHaveCount(2);
+
+    await page.keyboard.press('Control+Enter');
+
+    const submitButton = page.getByRole('button', {
+      name: 'Submit and go to next challenge'
+    });
+
+    // Mobile screen shifts submit button out of view and Playwright fails at scrolling with multiple editors open
+    if (isMobile) {
+      await submitButton.dispatchEvent('click');
+    } else {
+      await submitButton.click();
+    }
+
+    const editorsNextPage = getEditors(page);
+    await expect(editorsNextPage).toHaveCount(2);
+  });
 });