[{tester_id:"1",test_id:"1",score:40},{tester_id:"1",test_id:"2",score:50},{tester_id:"1",test_id:"3",score:70},{tester_id:"2",test_id:"1",score:50},{tester_id:"3",test_id:"2",score:20},{tester_id:"3",test_id:"3",score:60},{tester_id:"7",test_id:"5",score:40},{tester_id:"8",test_id:"4",score:50},{tester_id:"9",test_id:"4",score:70},]

db.collection.aggregate([{$match:{"tester_id":"1"}},{"$lookup":{"from":"collection","let":{"score":"$score"},"localField":"tester_id","foreignField":"test_id","pipeline":[{$match:{$expr:{$gte:["$score","$$score"]}}}],"as":"result"}}])