test: demonstrate SSR failure before the preview update

.github/workflows/ci.yml

@@ -0,0 +1,39 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  ssr:
+    name: SSR and build (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 15
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6
+      - uses: voidzero-dev/setup-vp@49c3e4e92c52e7f8392712a9267bbe71c5ab30e5 # v1.19.0
+        with:
+          version-file: package.json
+          node-version: "24.14.1"
+          run-install: false
+      - name: Install locked dependencies
+        run: vp install --frozen-lockfile
+      - name: Show tool versions
+        run: vp --version
+      - name: Test server-rendered routes
+        run: vp test run
+      - name: Build for production
+        run: vp build

tests/ssr.test.ts

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+import { execFileSync, spawn } from "node:child_process";
+import { setTimeout as delay } from "node:timers/promises";
+import { fileURLToPath } from "node:url";
+import { expect, test } from "vite-plus/test";
+
+test("vp dev renders both routes on the server", async ({ onTestFinished }) => {
+  const cli = fileURLToPath(new URL("../node_modules/vite-plus/bin/vp", import.meta.url));
+  const server = spawn(process.execPath, [cli, "dev", "--host", "127.0.0.1", "--port", "0"], {
+    cwd: fileURLToPath(new URL("..", import.meta.url)),
+    env: { ...process.env, NO_COLOR: "1", BROWSER: "none" },
+    detached: process.platform !== "win32",
+    stdio: ["ignore", "pipe", "pipe"],
+  });
+  let output = "";
+  let spawnError: Error | undefined;
+  server.on("error", (error) => {
+    spawnError = error;
+  });
+  server.stdout.on("data", (chunk) => {
+    output += chunk;
+  });
+  server.stderr.on("data", (chunk) => {
+    output += chunk;
+  });
+
+  onTestFinished(() => {
+    // The CLI starts Vite in a child process. Stop the full process tree.
+    if (server.pid) {
+      if (process.platform === "win32") {
+        execFileSync("taskkill", ["/pid", String(server.pid), "/T", "/F"], { stdio: "ignore" });
+      } else {
+        try {
+          process.kill(-server.pid, "SIGTERM");
+        } catch (error) {
+          if ((error as NodeJS.ErrnoException).code !== "ESRCH") throw error;
+        }
+      }
+    }
+  });
+
+  const deadline = Date.now() + 30_000;
+  let baseUrl: string | undefined;
+  while (Date.now() < deadline) {
+    if (spawnError) throw spawnError;
+    if (server.exitCode !== null) throw new Error(`Dev server exited:\n${output}`);
+    baseUrl = output.match(/http:\/\/127\.0\.0\.1:[1-9]\d*/)?.[0];
+    if (baseUrl) break;
+    await delay(100);
+  }
+  if (!baseUrl) throw new Error(`Dev server did not start:\n${output}`);
+
+  for (const [route, content] of [
+    ["/", "Start simple, ship quickly."],
+    ["/about", "A small starter with room to grow."],
+  ]) {
+    const response = await fetch(`${baseUrl}${route}`, { signal: AbortSignal.timeout(20_000) });
+    const html = await response.text();
+    expect(response.status, `${route}: ${html}`).toBe(200);
+    expect(response.headers.get("content-type")).toContain("text/html");
+    expect(html).toContain(content);
+  }
+}, 90_000);