fix: filter subscription with pubsubTopic1 and decoder with pubsubTopic2

packages/core/src/lib/filter/index.ts

@@ -74,6 +74,16 @@ class Subscription {
     callback: Callback<T>
   ): Promise<void> {
     const decodersArray = Array.isArray(decoders) ? decoders : [decoders];
+
+    // check that all decoders are configured for the same pubsub topic as this subscription
+    decodersArray.forEach((decoder) => {
+      if (decoder.pubsubTopic !== this.pubsubTopic) {
+        throw new Error(
+          `Pubsub topic not configured: decoder is configured for pubsub topic ${decoder.pubsubTopic} but this subscription is for pubsub topic ${this.pubsubTopic}. Please create a new Subscription for the different pubsub topic.`
+        );
+      }
+    });
+
     const decodersGroupedByCT = groupByContentTopic(decodersArray);
     const contentTopics = Array.from(decodersGroupedByCT.keys());
 

packages/tests/tests/filter/multiple_pubsub.node.spec.ts

@@ -146,4 +146,15 @@ describe("Waku Filter V2: Multiple PubSubtopics", function () {
       expectedMessageText: "M2"
     });
   });
+
+  it("Should fail to subscribe with decoder with wrong pubsubTopic", async function () {
+    // this subscription object is set up with the `customPubsubTopic` but we're passing it a Decoder with the `DefaultPubsubTopic`
+    try {
+      await subscription.subscribe([TestDecoder], messageCollector.callback);
+    } catch (error) {
+      expect((error as Error).message).to.include(
+        "Pubsub topic not configured"
+      );
+    }
+  });
 });