test(react-start): make basic-tsr-config test more strict (#3611)

make basic-tsr-config test more strict:
- #3597

---------

Co-authored-by: Sean Cassiere <[email protected]>

Author: birkskyum

e2e/react-start/basic-tsr-config/package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "dev": "vinxi dev --port 3000",
     "dev:e2e": "vinxi dev",
-    "build": "vinxi build && tsc --noEmit",
+    "build": "rimraf ./count.txt && vinxi build && tsc --noEmit",
     "start": "vinxi start",
     "test:e2e": "playwright test --project=chromium"
   },

e2e/react-start/basic-tsr-config/src/app/routes/index.tsx

@@ -1,18 +1,22 @@
+import fs from 'node:fs'
 import { createFileRoute, useRouter } from '@tanstack/react-router'
 import { createServerFn } from '@tanstack/react-start'
 
-let count = 0
+const filePath = 'count.txt'
 
-const getCount = createServerFn({ method: 'GET' }).handler(() => {
-  return count
+const getCount = createServerFn({
+  method: 'GET',
+}).handler(async () => {
+  const number = await fs.promises.readFile(filePath, 'utf-8').catch(() => '0')
+  return parseInt(number || '0')
 })
 
 const updateCount = createServerFn({ method: 'POST' })
-  .validator((addBy: number) => addBy)
-  .handler(({ data: addBy }) => {
-    count += addBy
+  .validator((d: number) => d)
+  .handler(async ({ data }) => {
+    const count = await getCount()
+    await fs.promises.writeFile(filePath, `${count + data}`)
   })
-
 export const Route = createFileRoute('/')({
   component: Home,
   loader: async () => await getCount(),
@@ -24,6 +28,7 @@ function Home() {
 
   return (
     <button
+      data-testid="add-button"
       onClick={() => {
         updateCount({ data: 1 }).then(() => {
           router.invalidate()

e2e/react-start/basic-tsr-config/tests/app.spec.ts

@@ -3,7 +3,8 @@ import { expect, test } from '@playwright/test'
 test('opening the app', async ({ page }) => {
   await page.goto('/')
 
-  await expect(page.getByText('Add 1 to 0?')).toBeTruthy()
-  await page.click('button')
-  await expect(page.getByText('Add 1 to 1?')).toBeTruthy()
+  await expect(page.getByTestId('add-button')).toContainText('Add 1 to 0?')
+  await page.getByTestId('add-button').click()
+  await page.waitForLoadState('networkidle')
+  await expect(page.getByTestId('add-button')).toContainText('Add 1 to 1?')
 })