test(cron): improve fire-and-forget harness coverage

src/cron/service.test-harness.ts

@@ -51,6 +51,22 @@ export function createCronStoreHarness(options?: { prefix?: string }) {
   return { makeStorePath };
 }
 
+export async function writeCronStoreSnapshot(params: { storePath: string; jobs: CronJob[] }) {
+  await fs.mkdir(path.dirname(params.storePath), { recursive: true });
+  await fs.writeFile(
+    params.storePath,
+    JSON.stringify(
+      {
+        version: 1,
+        jobs: params.jobs,
+      },
+      null,
+      2,
+    ),
+    "utf-8",
+  );
+}
+
 export function installCronTestHooks(options: {
   logger: ReturnType<typeof createNoopLogger>;
   baseTimeIso?: string;