sui-graphql-rust-sdk: add checkpoint fetching API [10/n]

Author: tpham-mysten

crates/sui-graphql/src/client/checkpoints.rs

@@ -0,0 +1,99 @@
+//! Checkpoint-related convenience methods.
+
+use sui_graphql_macros::Response;
+use sui_sdk_types::CheckpointContents;
+use sui_sdk_types::CheckpointSummary;
+
+use super::Client;
+use crate::bcs::Bcs;
+use crate::error::Error;
+
+/// A checkpoint response containing the summary and contents.
+///
+/// This struct combines the checkpoint header (summary) with its contents.
+#[derive(Debug, Clone)]
+#[non_exhaustive]
+pub struct CheckpointResponse {
+    /// The checkpoint summary (epoch, sequence number, timestamp, etc.)
+    pub summary: CheckpointSummary,
+    /// The checkpoint contents (transaction digests and signatures)
+    pub contents: CheckpointContents,
+}
+
+impl Client {
+    /// Fetch a checkpoint by its sequence number, or the latest checkpoint if not specified.
+    ///
+    /// Returns:
+    /// - `Ok(Some(response))` if the checkpoint exists
+    /// - `Ok(None)` if the checkpoint does not exist
+    /// - `Err(Error::Request)` for network errors
+    /// - `Err(Error::Base64)` / `Err(Error::Bcs)` for decoding errors
+    pub async fn get_checkpoint(
+        &self,
+        sequence_number: Option<u64>,
+    ) -> Result<Option<CheckpointResponse>, Error> {
+        #[derive(Response)]
+        struct Response {
+            #[field(path = "checkpoint.summaryBcs")]
+            summary_bcs: Option<String>,
+            #[field(path = "checkpoint.contentBcs")]
+            content_bcs: Option<String>,
+        }
+
+        const QUERY: &str = r#"
+            query($sequenceNumber: UInt53) {
+                checkpoint(sequenceNumber: $sequenceNumber) {
+                    summaryBcs
+                    contentBcs
+                }
+            }
+        "#;
+        let variables = serde_json::json!({ "sequenceNumber": sequence_number });
+
+        let response = self.query::<Response>(QUERY, variables).await?;
+
+        let Some(data) = response.into_data() else {
+            return Ok(None);
+        };
+
+        let (Some(summary_bcs), Some(content_bcs)) = (data.summary_bcs, data.content_bcs) else {
+            return Ok(None);
+        };
+
+        let summary = Bcs::<CheckpointSummary>::decode(&summary_bcs)?.into_inner();
+        let contents = Bcs::<CheckpointContents>::decode(&content_bcs)?.into_inner();
+
+        Ok(Some(CheckpointResponse { summary, contents }))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use wiremock::Mock;
+    use wiremock::MockServer;
+    use wiremock::ResponseTemplate;
+    use wiremock::matchers::method;
+    use wiremock::matchers::path;
+
+    #[tokio::test]
+    async fn test_get_checkpoint_not_found() {
+        let mock_server = MockServer::start().await;
+
+        Mock::given(method("POST"))
+            .and(path("/"))
+            .respond_with(ResponseTemplate::new(200).set_body_json(serde_json::json!({
+                "data": {
+                    "checkpoint": null
+                }
+            })))
+            .mount(&mock_server)
+            .await;
+
+        let client = Client::new(&mock_server.uri()).unwrap();
+
+        let result = client.get_checkpoint(Some(999999999)).await;
+        assert!(result.is_ok());
+        assert!(result.unwrap().is_none());
+    }
+}

crates/sui-graphql/src/client/mod.rs

@@ -1,6 +1,7 @@
 //! GraphQL client for Sui blockchain.
 
 pub(crate) mod chain;
+pub(crate) mod checkpoints;
 pub(crate) mod coins;
 mod objects;
 pub(crate) mod transactions;

crates/sui-graphql/src/lib.rs

@@ -15,6 +15,7 @@ pub mod scalars;
 pub use bcs::Bcs;
 pub use client::Client;
 pub use client::chain::Epoch;
+pub use client::checkpoints::CheckpointResponse;
 pub use client::coins::Balance;
 pub use client::transactions::TransactionResponse;
 pub use error::Error;