Cover Astro package entrypoints

Extend the Astro package regression test to assert that the JavaScript
and declaration entrypoints declared in package.json exist on disk.

This keeps the test aligned with the original packaging regression so
missing type outputs are caught before publication.

Author: dahlia

packages/astro/src/package.test.ts

@@ -1,13 +1,17 @@
 import { deepStrictEqual, strictEqual } from "node:assert/strict";
+import { access, readFile } from "node:fs/promises";
 import { createRequire } from "node:module";
+import { dirname, resolve } from "node:path";
 import test from "node:test";
+import { fileURLToPath } from "node:url";
 import type {
   Federation,
   FederationFetchOptions,
 } from "@fedify/fedify/federation";
 import type { APIContext } from "astro";
 
 const require = createRequire(import.meta.url);
+const packageDir = resolve(dirname(fileURLToPath(import.meta.url)), "..");
 
 type MockFederation<TContextData> = Pick<Federation<TContextData>, "fetch">;
 
@@ -28,6 +32,10 @@ function expectResponse(response: void | Response): Response {
   return response;
 }
 
+async function assertTargetExists(path: string): Promise<void> {
+  await access(resolve(packageDir, path));
+}
+
 test("self-reference ESM import exposes working Astro integration API", async () => {
   const mod = await import("@fedify/astro");
 
@@ -92,6 +100,24 @@ test(
   "self-reference CommonJS require exposes working Astro middleware API",
   { skip: "Deno" in globalThis },
   async () => {
+    const packageJson = JSON.parse(
+      await readFile(resolve(packageDir, "package.json"), "utf8"),
+    );
+    const exportMap = packageJson.exports["."];
+    const targets = [
+      packageJson.main,
+      packageJson.module,
+      packageJson.types,
+      exportMap.require.types,
+      exportMap.require.default,
+      exportMap.import.types,
+      exportMap.import.default,
+    ] as string[];
+
+    for (const target of new Set(targets)) {
+      await assertTargetExists(target);
+    }
+
     const mod = require("@fedify/astro") as typeof import("@fedify/astro");
 
     strictEqual(typeof mod.fedifyIntegration, "function");