Add tests for constant functionId and update serverFns config logic.

Author: zenios

e2e/react-start/server-functions/tests/server-functions.spec.ts

@@ -6,6 +6,20 @@ import type { Page } from '@playwright/test'
 
 const PORT = await getTestServerPort(packageJson.name)
 
+test('Server function URLs correctly include constant ids', async ({
+  page,
+}) => {
+  for (const currentPage of ['/submit-post-formdata', '/formdata-redirect']) {
+    await page.goto(currentPage)
+    await page.waitForLoadState('networkidle')
+
+    const form = page.locator('form')
+    const actionUrl = await form.getAttribute('action')
+
+    expect(actionUrl).toMatch(/^\/_serverFn\/constant_id/)
+  }
+})
+
 test('invoking a server function with custom response status code', async ({
   page,
 }) => {

e2e/react-start/server-functions/vite.config.ts

@@ -3,12 +3,25 @@ import tsConfigPaths from 'vite-tsconfig-paths'
 import { tanstackStart } from '@tanstack/react-start/plugin/vite'
 import viteReact from '@vitejs/plugin-react'
 
+const FUNCTIONS_WITH_CONSTANT_ID = [
+  'src/routes/submit-post-formdata.tsx--greetUser_createServerFn_handler',
+  'src/routes/formdata-redirect/index.tsx--greetUser_createServerFn_handler',
+]
+
 export default defineConfig({
   plugins: [
     tsConfigPaths({
       projects: ['./tsconfig.json'],
     }),
-    tanstackStart(),
+    tanstackStart({
+      serverFns: {
+        functionId: (opts) => {
+          if (FUNCTIONS_WITH_CONSTANT_ID.includes(opts.currentId))
+            return 'constant_id'
+          else return undefined
+        },
+      },
+    }),
     viteReact(),
   ],
 })