test: improve data migration suite (#4124)

tests/kit/utils/proxy.ts

@@ -0,0 +1,62 @@
+import type Test from '@playwright/test';
+import type { BrowserContext } from '@playwright/test';
+import express from 'express';
+import { createProxyMiddleware } from 'http-proxy-middleware';
+
+import { waitForEditorLoad } from './page-logic';
+
+export async function check8080Available(context: BrowserContext) {
+  // make sure 8080 is ready
+  const page = await context.newPage();
+  await page.goto('http://localhost:8080/');
+  await waitForEditorLoad(page);
+  await page.close();
+}
+
+export function setupProxyServer(test: typeof Test, dir: string) {
+  let app: express.Express;
+  let server: ReturnType<express.Express['listen']>;
+  test.beforeEach(() => {
+    app = express();
+    app.use(express.static(dir));
+    server = app.listen(8081);
+  });
+
+  test.afterEach(() => {
+    server.close();
+  });
+
+  return {
+    get app() {
+      return app;
+    },
+    get server() {
+      return server;
+    },
+    switchToNext: async function () {
+      // close previous express server
+      await new Promise<void>((resolve, reject) => {
+        server.close(err => {
+          if (err) {
+            reject(err);
+          }
+          resolve();
+        });
+      });
+      app = express();
+      app.use(
+        createProxyMiddleware({
+          target: 'http://localhost:8080',
+          pathFilter: ['**'],
+          changeOrigin: true,
+        })
+      );
+      return new Promise<void>(resolve => {
+        server = app.listen(8081, () => {
+          console.log('proxy to next.js server');
+          resolve();
+        });
+      });
+    },
+  };
+}