{ "data": [ { "_id": 1, "x": 11 }, { "_id": 2, "x": 22 } ], "collection_name": "default_write_concern_coll", "database_name": "default_write_concern_db", "runOn": [ { "minServerVersion": "4.2" } ], "tests": [ { "description": "Aggregate with $merge omits default write concern", "operations": [ { "object": "collection", "databaseOptions": { "writeConcern": {} }, "collectionOptions": { "writeConcern": {} }, "name": "aggregate", "arguments": { "pipeline": [ { "$match": { "_id": { "$gt": 1 } } }, { "$merge": { "into": "other_collection_name" } } ] } } ], "expectations": [ { "command_started_event": { "command": { "aggregate": "default_write_concern_coll", "pipeline": [ { "$match": { "_id": { "$gt": 1 } } }, { "$merge": { "into": "other_collection_name" } } ], "writeConcern": null } } } ], "outcome": { "collection": { "name": "other_collection_name", "data": [ { "_id": 2, "x": 22 } ] } } } ] }