refactor: move test utils to package (#3206)

tests/affine-local/e2e/theme.spec.ts

@@ -0,0 +1,30 @@
+import { resolve } from 'node:path';
+
+import { test, testResultDir } from '@affine-test/kit/playwright';
+import { openHomePage } from '@affine-test/kit/utils/load-page';
+import { waitEditorLoad } from '@affine-test/kit/utils/page-logic';
+import { expect } from '@playwright/test';
+
+// default could be anything, according to the system
+test('default white', async ({ browser }) => {
+  const context = await browser.newContext({
+    colorScheme: 'light',
+  });
+  const page = await context.newPage();
+  await openHomePage(page);
+  await waitEditorLoad(page);
+  const root = page.locator('html');
+  const themeMode = await root.evaluate(element =>
+    element.getAttribute('data-theme')
+  );
+  expect(themeMode).toBe('light');
+  await page.screenshot({
+    path: resolve(testResultDir, 'affine-light-theme.png'),
+  });
+  await page.getByTestId('editor-option-menu').click();
+  await page.getByTestId('change-theme-dark').click();
+  await page.waitForTimeout(50);
+  await page.screenshot({
+    path: resolve(testResultDir, 'affine-dark-theme.png'),
+  });
+});