Db hole 1047

packages/zaino-state/src/chain_index/tests.rs

@@ -1,5 +1,6 @@
 //! Zaino-State ChainIndex unit tests.
 
+mod best_chaintip;
 pub(crate) mod finalised_state;
 pub(crate) mod mempool;
 mod mockchain_tests;

packages/zaino-state/src/chain_index/tests/best_chaintip.rs

@@ -0,0 +1,39 @@
+//! Regression tests for `best_chaintip`.
+//!
+//! Tracks <https://github.com/zingolabs/zaino/issues/1047>: when the snapshot
+//! is `StillSyncingFinalizedState` and the source cannot currently produce
+//! the block at `validator_finalized_height`, `best_chaintip` surfaces the
+//! miss as `database_hole` — the corruption kind — instead of a retryable
+//! "not ready" signal.
+
+use super::load_test_vectors_and_sync_chain_index;
+use crate::chain_index::ChainIndex;
+use crate::{ChainIndexSnapshot, Height};
+
+/// Reaches the `StillSyncingFinalizedState` arm with a
+/// `validator_finalized_height` the source cannot serve, mirroring the
+/// cold-boot race where zebrad transiently can't produce block `tip - 100`.
+/// The error (if any) must not be a `database_hole`: that category means
+/// zaino's own on-disk index claims a height whose bytes are unreachable,
+/// which is not what happened here.
+#[tokio::test(flavor = "multi_thread")]
+async fn passthrough_miss_is_not_a_database_hole() {
+    let (_blocks, _indexer, index_reader, mockchain) =
+        load_test_vectors_and_sync_chain_index(false).await;
+
+    let above_tip = Height(mockchain.max_chain_height() + 1_000);
+    let fake_snapshot = ChainIndexSnapshot::StillSyncingFinalizedState {
+        validator_finalized_height: above_tip,
+    };
+
+    match index_reader.best_chaintip(&fake_snapshot).await {
+        Ok(_tip) => {}
+        Err(e) => {
+            let rendered = e.to_string();
+            assert!(
+                !rendered.contains("hole in validator database"),
+                "best_chaintip misclassified a passthrough miss as a database hole: {rendered}",
+            );
+        }
+    }
+}