fix: Infinite loop (#464)

Author: shahnami

src/services/blockchain/clients/stellar/client.rs

@@ -516,6 +516,7 @@ impl<T: Send + Sync + Clone + BlockchainTransport> BlockChainClient for StellarC
 		let mut blocks = Vec::new();
 		let target_block = end_block.unwrap_or(start_block);
 		let mut cursor: Option<String> = None;
+		let mut previous_cursor: Option<String> = None;
 		let mut current_iteration = 0;
 
 		while cursor.is_some() || current_iteration <= 0 {
@@ -606,10 +607,11 @@ impl<T: Send + Sync + Clone + BlockchainTransport> BlockChainClient for StellarC
 						.as_str()
 						.map(|s| s.to_string());
 
-					// If the cursor is the same as the start block, we have reached the end of the range
-					if cursor == Some(start_block.to_string()) {
+					// Break if the cursor did not advance (stalled pagination) or is absent
+					if cursor == previous_cursor {
 						break;
 					}
+					previous_cursor = cursor.clone();
 
 					if cursor.is_none() {
 						break;

tests/integration/blockchain/clients/stellar/client.rs

@@ -335,6 +335,73 @@ async fn test_get_blocks_pagination() {
 	second_mock.assert_async().await;
 }
 
+/// Regression test: cursor equal to start_block must NOT terminate pagination early.
+#[tokio::test]
+async fn test_get_blocks_cursor_equal_start_block_still_paginates() {
+	let mut server = Server::new_async().await;
+	let mock = create_stellar_valid_server_mock_network_response(&mut server);
+	let network = create_stellar_test_network_with_urls(vec![&server.url()]);
+
+	// Page 1: returns one ledger at sequence 10, cursor equals start_block ("10")
+	let first_response = json!({
+		"result": {
+			"ledgers": [{
+				"hash": "aaa",
+				"sequence": 10,
+				"ledgerCloseTime": "1734715051",
+				"headerXdr": "AAA",
+				"metadataXdr": "BBB"
+			}],
+			"cursor": "10"
+		}
+	});
+
+	// Page 2: returns the next ledger, pagination ends (null cursor)
+	let second_response = json!({
+		"result": {
+			"ledgers": [{
+				"hash": "bbb",
+				"sequence": 11,
+				"ledgerCloseTime": "1734715052",
+				"headerXdr": "AAA",
+				"metadataXdr": "BBB"
+			}],
+			"cursor": null
+		}
+	});
+
+	let first_mock = server
+		.mock("POST", "/")
+		.with_status(200)
+		.with_body(first_response.to_string())
+		.create_async()
+		.await;
+
+	let second_mock = server
+		.mock("POST", "/")
+		.with_status(200)
+		.with_body(second_response.to_string())
+		.create_async()
+		.await;
+
+	let client = StellarClient::new(&network).await.unwrap();
+	let result = client.get_blocks(10, Some(11)).await.unwrap();
+
+	assert_eq!(result.len(), 2, "expected both pages to be fetched");
+	match &result[0] {
+		BlockType::Stellar(block) => assert_eq!(block.sequence, 10),
+		_ => panic!("Expected Stellar block"),
+	}
+	match &result[1] {
+		BlockType::Stellar(block) => assert_eq!(block.sequence, 11),
+		_ => panic!("Expected Stellar block"),
+	}
+
+	mock.assert_async().await;
+	first_mock.assert_async().await;
+	second_mock.assert_async().await;
+}
+
 #[tokio::test]
 async fn test_get_contract_spec() {
 	let mut server = Server::new_async().await;