Assert on correct registeration of outputs index

Author: Antoine Riard

lightning/src/chain/channelmonitor.rs

@@ -1772,6 +1772,20 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 			let idx_and_scripts = txouts.iter().map(|o| (o.0, o.1.script_pubkey.clone())).collect();
 			self.outputs_to_watch.insert(txid.clone(), idx_and_scripts).is_none()
 		});
+		#[cfg(test)]
+		{
+		        // If we see a transaction for which we registered outputs previously,
+			// make sure the registered scriptpubkey at the expected index match
+			// the actual transaction output one. We failed this case before #653.
+			for tx in &txn_matched {
+				if let Some(outputs) = self.get_outputs_to_watch().get(&tx.txid()) {
+				        for (idx, idx_and_script) in outputs.iter().enumerate() {
+				                assert!(idx < tx.output.len());
+				                assert_eq!(tx.output[idx].script_pubkey, idx_and_script.1);
+				        }
+				}
+			}
+		}
 		watch_outputs
 	}