add close method to policyworker for testing purposes

packages/ditto/workers/policy.ts

@@ -86,4 +86,8 @@ export class PolicyWorker implements NPolicy {
       throw new Error(`DITTO_POLICY (error importing policy): ${conf.policy}`);
     }
   }
+
+  [Symbol.dispose]() {
+    this.worker.close();
+  }
 }

packages/ditto/workers/policy.worker.ts

@@ -85,6 +85,10 @@ export class CustomPolicy implements NPolicy {
 
     this.policy = new PipePolicy(policies);
   }
+
+  close() {
+    self.close();
+  }
 }
 
 Comlink.expose(new CustomPolicy());