{
    "medialib": [
        { "generic/rating": 1, "other/rating": 2, "title": "song a" },
        { "generic/rating": 2, "other/rating": 1, "title": "song b" },
        {                                         "title": "song c" }
    ],
    "collection": {
        "type": "complement",
        "operands": [{
            "type": "equals",
            "attributes": {
                "type": "value",
                "field": "rating",
                "value": "1"
            },
            "operands": [{ "type": "universe" }]
        }]
    },
    "specification": {
        "type": "cluster-list",
        "cluster-by": "id",
        "data": {
            "type": "metadata",
            "get": ["value"],
            "fields": ["title"],
            "aggregate": "first"
        }
    },
    "expected": {
        "result": [ "song c" ]
    }
}

Add test for complement with sources.
BUG(2277): Add test for complement with sources.

Just confirms that it works so the ticket can be closed.
