test: verify app startup from persisted engine snapshot

test/app.test.js

@@ -249,6 +249,36 @@ test("emits persistence snapshots on mutating actions", () => {
   assert.equal(typeof latest.engine, "object");
 });
 
+test("can boot app from previously persisted state snapshot", () => {
+  const snapshots = [];
+  const app1 = createApp({
+    onMutation(state) {
+      snapshots.push(state);
+    },
+  });
+
+  call(app1, {
+    method: "POST",
+    path: "/app/actions/topup",
+    headers: { cookie: "xartaudio_user=restart-user" },
+    body: "amount=6",
+  });
+
+  const persistedState = snapshots[snapshots.length - 1];
+  const app2 = createApp({
+    initialState: persistedState,
+  });
+
+  const wallet = call(app2, {
+    method: "GET",
+    path: "/api/me/wallet",
+    headers: { cookie: "xartaudio_user=restart-user" },
+  });
+
+  assert.equal(wallet.status, 200);
+  assert.equal(JSON.parse(wallet.body).balance, 6);
+});
+
 test("rate limits repeated webhook calls", () => {
   const app = createApp({
     config: {