fix(cli): emit one JSON object per ref in list-refs (#4169)

The nested comprehension emitted one object per retention property, so a single snapshot ref produced several JSON objects. Build one object per ref and merge its properties into it.

Author: aayusbhat26

pyiceberg/cli/output.py

@@ -272,10 +272,4 @@ def version(self, version: str) -> None:
         self._out({"version": version})
 
     def describe_refs(self, refs: list[tuple[str, SnapshotRefType, dict[str, str]]]) -> None:
-        self._out(
-            [
-                {"name": name, "type": type, detail_key: detail_val}
-                for name, type, detail in refs
-                for detail_key, detail_val in detail.items()
-            ]
-        )
+        self._out([{"name": name, "type": ref_type, **detail} for name, ref_type, detail in refs])

tests/cli/test_output.py

@@ -14,3 +14,35 @@
 #  KIND, either express or implied.  See the License for the
 #  specific language governing permissions and limitations
 #  under the License.
+import json
+
+import pytest
+
+from pyiceberg.cli.output import JsonOutput
+from pyiceberg.table.refs import SnapshotRefType
+
+
+def test_json_describe_refs_emits_one_object_per_ref(capsys: pytest.CaptureFixture[str]) -> None:
+    JsonOutput().describe_refs(
+        [
+            (
+                "main",
+                SnapshotRefType.BRANCH,
+                {
+                    "min_snapshots_to_keep": "1",
+                    "max_snapshot_age_ms": "432000000",
+                    "max_ref_age_ms": "forever",
+                },
+            )
+        ]
+    )
+
+    assert json.loads(capsys.readouterr().out) == [
+        {
+            "name": "main",
+            "type": "branch",
+            "min_snapshots_to_keep": "1",
+            "max_snapshot_age_ms": "432000000",
+            "max_ref_age_ms": "forever",
+        }
+    ]