fix(app): keep typechecking after Expo generates environment types (#6656)

Expo declares NODE_ENV readonly after web startup. Preserve the early test environment setup with Object.assign and exercise the real configuration with Expo types in a failing-first compiler regression.

Co-authored-by: paseo-bot[bot] <266920839+paseo-bot[bot]@users.noreply.github.com>

packages/app/vitest-environment.test.ts

@@ -1,4 +1,5 @@
 import { spawnSync } from "node:child_process";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
 import { createRequire } from "node:module";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
@@ -8,6 +9,35 @@ const appDir = fileURLToPath(new URL(".", import.meta.url));
 const rootDir = path.resolve(appDir, "../..");
 const require = createRequire(import.meta.url);
 const vitestEntry = path.join(path.dirname(require.resolve("vitest/package.json")), "vitest.mjs");
+const tsgoEntry = path.join(
+  path.dirname(require.resolve("@typescript/native-preview/package.json")),
+  "bin/tsgo.js",
+);
+
+it("the test configuration typechecks with Expo's generated environment declaration", () => {
+  const fixtureDir = mkdtempSync(path.join(appDir, ".vitest-expo-env-"));
+  try {
+    writeFileSync(path.join(fixtureDir, "expo-env.d.ts"), '/// <reference types="expo/types" />\n');
+    writeFileSync(
+      path.join(fixtureDir, "tsconfig.json"),
+      JSON.stringify({
+        extends: "../tsconfig.json",
+        files: ["../vitest.config.ts", "expo-env.d.ts"],
+        include: [],
+      }),
+    );
+    const result = spawnSync(
+      process.execPath,
+      [tsgoEntry, "--noEmit", "--project", path.join(fixtureDir, "tsconfig.json")],
+      { cwd: appDir, encoding: "utf8", timeout: 30_000 },
+    );
+
+    expect(result.error).toBeUndefined();
+    expect(result.status, result.stdout + result.stderr).toBe(0);
+  } finally {
+    rmSync(fixtureDir, { recursive: true, force: true });
+  }
+}, 40_000);
 
 it.each([
   {

packages/app/vitest.config.ts

@@ -4,7 +4,7 @@ import path from "path";
 import fs from "fs";
 
 // Set this before Vite resolves dependencies and Vitest starts its workers.
-process.env.NODE_ENV = "test";
+Object.assign(process.env, { NODE_ENV: "test" });
 
 const appNodeModules = path.resolve(__dirname, "node_modules");
 const rootNodeModules = path.resolve(__dirname, "../../node_modules");