test(catalog-rest): cover endpoint config parsing + fixture integration test

Unit tests in types.rs for CatalogConfig endpoint parsing: a valid advertised
list parses, a missing field deserializes to None, and a single malformed
endpoint string fails the whole parse (matching the Java reference's
ConfigResponseParser, which rejects rather than silently dropping).

Integration test in crates/integration_tests exercising
RestCatalog::supports_endpoint against the real iceberg-rest-fixture
GET /v1/config response.

Author: huan233usc

crates/catalog/rest/src/types.rs

@@ -480,4 +480,32 @@ mod tests {
         assert_eq!(request.stage_create, None);
         assert!(request.properties.is_empty());
     }
+
+    #[test]
+    fn config_parses_advertised_endpoints() {
+        let json = r#"{"overrides":{},"defaults":{},
+            "endpoints":["GET /v1/{prefix}/namespaces","POST /v1/{prefix}/namespaces/{namespace}/tables"]}"#;
+        let config: CatalogConfig = serde_json::from_str(json).unwrap();
+        let endpoints = config.endpoints.expect("endpoints should be present");
+        assert_eq!(endpoints.len(), 2);
+        assert!(endpoints.contains(&"GET /v1/{prefix}/namespaces".parse().unwrap()));
+    }
+
+    #[test]
+    fn config_without_endpoints_field_deserializes_to_none() {
+        // `Option<Vec<Endpoint>>` defaults to `None` for a missing field without
+        // an explicit `#[serde(default)]`.
+        let config: CatalogConfig =
+            serde_json::from_str(r#"{"overrides":{},"defaults":{}}"#).unwrap();
+        assert!(config.endpoints.is_none());
+    }
+
+    #[test]
+    fn malformed_endpoint_fails_config_parse() {
+        // A single malformed endpoint string fails the whole config parse,
+        // matching the Java reference (`ConfigResponseParser` rejects it rather
+        // than silently dropping it).
+        let json = r#"{"overrides":{},"defaults":{},"endpoints":["GET_v1/namespaces"]}"#;
+        assert!(serde_json::from_str::<CatalogConfig>(json).is_err());
+    }
 }

crates/integration_tests/tests/endpoint_negotiation_test.rs

@@ -0,0 +1,60 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//! Integration test for REST endpoint capability negotiation, run against the
+//! `iceberg-rest-fixture` started by `dev/docker-compose.yaml`.
+
+use std::collections::HashMap;
+
+use iceberg::CatalogBuilder;
+use iceberg_catalog_rest::{Endpoint, REST_CATALOG_PROP_URI, RestCatalogBuilder};
+use iceberg_test_utils::{get_rest_catalog_endpoint, set_up};
+
+#[tokio::test]
+async fn test_supports_endpoint_from_server_config() {
+    set_up();
+
+    // Endpoint negotiation only reads `GET /v1/config`, so the catalog needs
+    // just the REST URI — no storage configuration is involved.
+    let config = HashMap::from([(
+        REST_CATALOG_PROP_URI.to_string(),
+        get_rest_catalog_endpoint(),
+    )]);
+    let catalog = RestCatalogBuilder::default()
+        .load("rest", config)
+        .await
+        .unwrap();
+
+    // `HEAD .../tables/{table}` (table-exists) is advertised by the fixture but
+    // is NOT part of `DEFAULT_ENDPOINTS`. Asserting it is supported confirms the
+    // server's advertised list — not the default fallback — is what gets
+    // negotiated (the fallback would report it unsupported).
+    let table_exists: Endpoint = "HEAD /v1/{prefix}/namespaces/{namespace}/tables/{table}"
+        .parse()
+        .unwrap();
+    assert!(catalog.supports_endpoint(&table_exists).await.unwrap());
+
+    // A base operation is advertised and supported too.
+    let load_table: Endpoint = "GET /v1/{prefix}/namespaces/{namespace}/tables/{table}"
+        .parse()
+        .unwrap();
+    assert!(catalog.supports_endpoint(&load_table).await.unwrap());
+
+    // A path the fixture does not advertise is reported unsupported.
+    let bogus: Endpoint = "GET /v1/{prefix}/does-not-exist".parse().unwrap();
+    assert!(!catalog.supports_endpoint(&bogus).await.unwrap());
+}