Add test for starter environment project package serialization

tests/serialization/starter-environment-project-package.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+
+import { applyStarterEnvironmentAssetsToProjectDocument } from "../../src/assets/starter-environment-assets";
+import { createEmptyProjectDocument } from "../../src/document/scene-document";
+import {
+  loadProjectPackage,
+  saveProjectPackage
+} from "../../src/serialization/project-package";
+
+describe("starter environment project packages", () => {
+  it("saves and reloads builtin starter environments without asset storage", async () => {
+    const document = applyStarterEnvironmentAssetsToProjectDocument(
+      createEmptyProjectDocument()
+    );
+
+    const bytes = await saveProjectPackage(document, null);
+    const loadedDocument = await loadProjectPackage(bytes, null);
+
+    expect(loadedDocument).toEqual(document);
+  });
+});