Add tests for offline sync with db boostraps (#2152)

Resolves [2034](#2034)

Author: avinassh

libsql/src/sync/test.rs

@@ -251,6 +251,73 @@ async fn test_sync_context_retry_on_error() {
     assert_eq!(server.frame_count(), 1);
 }
 
+#[tokio::test]
+async fn test_bootstrap_db_downloads_export() {
+    let server = MockServer::start();
+    let temp_dir = tempdir().unwrap();
+    let db_path = temp_dir.path().join("bootstrap.db");
+
+    // Seed metadata so SyncContext can be constructed (generation=1)
+    gen_metadata_file(&db_path, 3278479626, 0, 0, 1);
+
+    let mut sync_ctx = SyncContext::new(
+        server.connector(),
+        db_path.to_str().unwrap().to_string(),
+        server.url(),
+        None,
+        None,
+    )
+    .await
+    .unwrap();
+
+
+    let _ = std::fs::remove_file(&db_path);
+    let _ = std::fs::remove_file(format!("{}-info", db_path.to_str().unwrap()));
+
+    // Bootstrap should fetch /info and then /export/{generation}
+    crate::sync::bootstrap_db(&mut sync_ctx).await.unwrap();
+
+    assert!(std::path::Path::new(&db_path).exists());
+    assert!(std::path::Path::new(&format!("{}-info", db_path.to_str().unwrap())).exists());
+
+    assert_eq!(sync_ctx.durable_generation(), 1);
+    assert_eq!(sync_ctx.durable_frame_num(), 0);
+
+    assert!(server.request_count() >= 2);
+}
+
+#[tokio::test]
+async fn test_bootstrap_db_is_idempotent() {
+    let server = MockServer::start();
+    let temp_dir = tempdir().unwrap();
+    let db_path = temp_dir.path().join("bootstrap2.db");
+
+
+    gen_metadata_file(&db_path, 3278479626, 0, 0, 1);
+
+    let mut sync_ctx = SyncContext::new(
+        server.connector(),
+        db_path.to_str().unwrap().to_string(),
+        server.url(),
+        None,
+        None,
+    )
+    .await
+    .unwrap();
+
+    let _ = std::fs::remove_file(&db_path);
+    let _ = std::fs::remove_file(format!("{}-info", db_path.to_str().unwrap()));
+
+
+    crate::sync::bootstrap_db(&mut sync_ctx).await.unwrap();
+    let first_requests = server.request_count();
+
+    // Second bootstrap should be a no-op (no new network calls)
+    crate::sync::bootstrap_db(&mut sync_ctx).await.unwrap();
+    let second_requests = server.request_count();
+    assert_eq!(first_requests, second_requests);
+}
+
 #[test]
 fn test_hash_verification() {
     let mut metadata = MetadataJson {
@@ -328,12 +395,14 @@ impl Service<http::Uri> for MockConnector {
     }
 }
 
+#[allow(dead_code)]
 struct MockServer {
     url: String,
     frame_count: Arc<AtomicU32>,
     connector: ConnectorService,
     return_error: Arc<AtomicBool>,
     request_count: Arc<AtomicU32>,
+    export_bytes: Arc<Vec<u8>>, // bytes returned by /export/{generation}
 }
 
 impl MockServer {
@@ -342,6 +411,25 @@ impl MockServer {
         let return_error = Arc::new(AtomicBool::new(false));
         let request_count = Arc::new(AtomicU32::new(0));
 
+        let export_bytes: Arc<Vec<u8>> = {
+            use crate::local::Database;
+            use crate::database::OpenFlags;
+            use std::fs;
+            use tempfile::NamedTempFile;
+
+            let tmp = NamedTempFile::new().expect("temp file for export db");
+            let path = tmp.path().to_path_buf();
+            let db = Database::open(path.to_str().unwrap().to_string(), OpenFlags::default())
+                .expect("open export db");
+            let conn = db.connect().expect("connect export db");
+
+            let _ = conn.query("CREATE TABLE IF NOT EXISTS t(x INTEGER);", crate::params::Params::None);
+            drop(conn);
+            drop(db);
+            let bytes = fs::read(&path).expect("read export db bytes");
+            Arc::new(bytes)
+        };
+
         // Create the mock connector with Some(client_stream)
         let (tx, mut rx) = tokio::sync::mpsc::channel(1);
         let mock_connector = MockConnector { tx };
@@ -353,18 +441,21 @@ impl MockServer {
             connector,
             return_error: return_error.clone(),
             request_count: request_count.clone(),
+            export_bytes: export_bytes.clone(),
         };
 
         // Spawn the server handler
         let frame_count_clone = frame_count.clone();
         let return_error_clone = return_error.clone();
         let request_count_clone = request_count.clone();
+        let export_bytes_clone = export_bytes.clone();
 
         tokio::spawn(async move {
             while let Some(server_stream) = rx.recv().await {
                 let frame_count_clone = frame_count_clone.clone();
                 let return_error_clone = return_error_clone.clone();
                 let request_count_clone = request_count_clone.clone();
+                let export_bytes_clone = export_bytes_clone.clone();
 
                 tokio::spawn(async move {
                     use hyper::server::conn::Http;
@@ -377,6 +468,7 @@ impl MockServer {
                         let frame_count = frame_count_clone.clone();
                         let return_error = return_error_clone.clone();
                         let request_count = request_count_clone.clone();
+                        let export_bytes = export_bytes_clone.clone();
                         async move {
                             request_count.fetch_add(1, Ordering::SeqCst);
                             if return_error.load(Ordering::SeqCst) {
@@ -388,9 +480,9 @@ impl MockServer {
                                 );
                             }
 
-                            let current_count = frame_count.fetch_add(1, Ordering::SeqCst);
-
                             if req.uri().path().contains("/sync/") {
+                                // Count only sync requests as frames to keep tests stable.
+                                let current_count = frame_count.fetch_add(1, Ordering::SeqCst);
                                 // Return the max_frame_no that has been accepted
                                 let response = serde_json::json!({
                                     "status": "ok",
@@ -404,6 +496,23 @@ impl MockServer {
                                         .body(Body::from(response.to_string()))
                                         .unwrap(),
                                 )
+                            } else if req.uri().path().eq("/info") {
+                                let response = serde_json::json!({
+                                    "current_generation": 1
+                                });
+                                Ok::<_, hyper::Error>(
+                                    http::Response::builder()
+                                        .status(200)
+                                        .body(Body::from(response.to_string()))
+                                        .unwrap(),
+                                )
+                            } else if req.uri().path().starts_with("/export/") {
+                                Ok::<_, hyper::Error>(
+                                    http::Response::builder()
+                                        .status(200)
+                                        .body(Body::from(export_bytes.as_ref().clone()))
+                                        .unwrap(),
+                                )
                             } else {
                                 Ok(http::Response::builder()
                                     .status(404)
@@ -489,4 +598,4 @@ fn gen_metadata_file(db_path: &Path, hash: u32, version: u32, durable_frame_num:
         .as_bytes(),
     )
     .unwrap();
-}
+}