mongodb/jstests/sharding/mr_output_sharded_validation.js

// Tests that the cluster mapReduce command will prevent outputting to a sharded collection without
// the sharded: true option specified. Also tests that the command will correctly clean up the
// output namespace of the first phase of a mapReduce with sharded input before the final result
// collection is created. This test was designed to reproduce SERVER-36966.
(function() {
"use strict";

const st = new ShardingTest({shards: 2, config: 1, verbose: ''});

const mongosDB = st.s.getDB("test");
st.shardColl(mongosDB.foo, {_id: 1}, {_id: 0}, {_id: -1});

assert.commandWorked(mongosDB.foo.insert([{_id: 1}, {_id: 2}]));

assert.commandWorked(
    mongosDB.adminCommand({shardCollection: mongosDB.output.getFullName(), key: {_id: "hashed"}}));

assert.commandWorked(mongosDB.foo.mapReduce(
    function() {
        emit(this._id, 1);
    },
    function(key, values) {
        return Array.sum(values);
    },
    {out: {replace: "output", sharded: true}}));

// Test that using just a collection name without specifying a merge mode or the 'sharded: true'
// information will fail if the named collection is sharded.
const error = assert.throws(() => mongosDB.foo.mapReduce(
                                function() {
                                    emit(this._id, 1);
                                },
                                function(key, values) {
                                    return Array.sum(values);
                                },
                                {out: "output"}));
assert.eq(error.code, 15920);

for (let name of mongosDB.getCollectionNames()) {
    assert.eq(-1, name.indexOf("tmp.mrs"), name);
}

st.stop();
}());