(function() {
"use strict";
const collName = "distinct1";
const coll = db.getCollection(collName);
coll.drop();

assert.eq(0, coll.distinct("a").length, "test empty");

assert.commandWorked(coll.insert({a: 1}));
assert.commandWorked(coll.insert({a: 2}));
assert.commandWorked(coll.insert({a: 2}));
assert.commandWorked(coll.insert({a: 2}));
assert.commandWorked(coll.insert({a: 3}));

// Test that distinct returns all the distinct values.
assert.eq([1, 2, 3], coll.distinct("a").sort(), "distinct returned unexpected results");

// Test that distinct respects the query condition.
assert.eq([1, 2],
          coll.distinct("a", {a: {$lt: 3}}).sort(),
          "distinct with query returned unexpected results");

assert(coll.drop());

assert.commandWorked(coll.insert({a: {b: "a"}, c: 12}));
assert.commandWorked(coll.insert({a: {b: "b"}, c: 12}));
assert.commandWorked(coll.insert({a: {b: "c"}, c: 12}));
assert.commandWorked(coll.insert({a: {b: "c"}, c: 12}));

// Test that distinct works on fields in embedded documents.
assert.eq(["a", "b", "c"],
          coll.distinct("a.b").sort(),
          "distinct on dotted field returned unexpected results");

assert(coll.drop());

assert.commandWorked(coll.insert({_id: 1, a: 1}));
assert.commandWorked(coll.insert({_id: 2, a: 2}));

// Test that distinct works on the _id field.
assert.eq([1, 2], coll.distinct("_id").sort(), "distinct on _id returned unexpected results");

// Test that distinct works with a query on the _id field.
assert.eq(
    [1], coll.distinct("a", {_id: 1}), "distinct with query on _id returned unexpected results");

assert(coll.drop());

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

// Test running the distinct command directly, rather than via shell helper.
let res = assert.commandWorked(db.runCommand({distinct: collName, key: "a"}));
assert.eq([1, 2, 3, 4], res.values.sort());

res = assert.commandWorked(db.runCommand({distinct: collName, key: "a", query: null}));
assert.eq([1, 2, 3, 4], res.values.sort());

res = assert.commandWorked(db.runCommand({distinct: collName, key: "a", query: {b: 2}}));
assert.eq([1, 2, 3], res.values.sort());

assert.commandFailed(db.runCommand({distinct: collName, key: "a", query: 1}));
}());