// @tags: [
//   # mapReduce does not support afterClusterTime.
//   does_not_support_causal_consistency,
//   does_not_support_stepdowns,
//   uses_map_reduce_with_temp_collections,
//   assumes_unsharded_collection,
// ]
//
(function() {
"use strict";

const coll = db.mr_replace;
coll.drop();

assert.commandWorked(coll.insert([{a: [1, 2]}, {a: [2, 3]}, {a: [3, 4]}]));

const outCollStr = "mr_replace_col";
const outDbStr = "mr_db";
const outDb = db.getMongo().getDB(outDbStr);
// insert into outDb so map reduce doesn't fail to find it.
assert.commandWorked(outDb.random_coll.insert({val: 1}));
const outColl = outDb[outCollStr];

const mapFn = function() {
    for (i = 0; i < this.a.length; i++)
        emit(this.a[i], 1);
};
const reduceFn = function(k, vs) {
    return Array.sum(vs);
};

let res = assert.commandWorked(
    coll.mapReduce(mapFn, reduceFn, {out: {replace: outCollStr, db: outDbStr}}));
const expected = [{_id: 1, value: 1}, {_id: 2, value: 2}, {_id: 3, value: 2}, {_id: 4, value: 1}];
let actual = outColl.find().sort({_id: 1}).toArray();
assert.eq(expected, actual);

assert.eq(res.result.collection, outCollStr, "Wrong collection " + res.result.collection);
assert.eq(res.result.db, outDbStr, "Wrong db " + res.result.db);

// Run the whole thing again and make sure it does the same thing.
assert.commandWorked(outColl.insert({_id: 5, value: 1}));
assert.commandWorked(coll.mapReduce(mapFn, reduceFn, {out: {replace: outCollStr, db: outDbStr}}));
actual = outColl.find().sort({_id: 1}).toArray();
assert.eq(expected, actual);
}());