// Cannot implicitly shard accessed collections because of collection existing when none
// expected.
// Tagged with requires_fcv_44 due to change in the implementation of the returnKey query
// modifier, along with stricter rules for $-prefixed field name, which are not compatible
// with older versions.
// @tags: [
//   assumes_no_implicit_collection_creation_after_drop,
//   does_not_support_stepdowns,
//   requires_non_retryable_commands,
//   requires_non_retryable_writes,
//   requires_fcv_44
// ]

// Integration tests for the collation feature.
(function() {
'use strict';

load("jstests/libs/analyze_plan.js");
load("jstests/libs/get_index_helpers.js");
// For isWiredTiger.
load("jstests/concurrency/fsm_workload_helpers/server_types.js");
// For isReplSet
load("jstests/libs/fixture_helpers.js");

var coll = db.collation;
coll.drop();

var explainRes;
var writeRes;
var planStage;

var isMaster = db.runCommand("ismaster");
assert.commandWorked(isMaster);
var isMongos = (isMaster.msg === "isdbgrid");

var assertIndexHasCollation = function(keyPattern, collation) {
    var indexSpecs = coll.getIndexes();
    var found = GetIndexHelpers.findByKeyPattern(indexSpecs, keyPattern, collation);
    assert.neq(null,
               found,
               "Index with key pattern " + tojson(keyPattern) + " and collation " +
                   tojson(collation) + " not found: " + tojson(indexSpecs));
};

var getQueryCollation = function(explainRes) {
    if (explainRes.queryPlanner.hasOwnProperty("collation")) {
        return explainRes.queryPlanner.collation;
    }

    if (explainRes.queryPlanner.winningPlan.hasOwnProperty("shards") &&
        explainRes.queryPlanner.winningPlan.shards.length > 0 &&
        explainRes.queryPlanner.winningPlan.shards[0].hasOwnProperty("collation")) {
        return explainRes.queryPlanner.winningPlan.shards[0].collation;
    }

    return null;
};

//
// Test using db.createCollection() to make a collection with a default collation.
//

// Attempting to create a collection with an invalid collation should fail.
assert.commandFailed(db.createCollection("collation", {collation: "not an object"}));
assert.commandFailed(db.createCollection("collation", {collation: {}}));
assert.commandFailed(db.createCollection("collation", {collation: {blah: 1}}));
assert.commandFailed(db.createCollection("collation", {collation: {locale: "en", blah: 1}}));
assert.commandFailed(db.createCollection("collation", {collation: {locale: "xx"}}));
assert.commandFailed(db.createCollection("collation", {collation: {locale: "en", strength: 99}}));

// Attempting to create a collection whose collation version does not match the collator version
// produced by ICU should result in failure with a special error code.
assert.commandFailedWithCode(
    db.createCollection("collation", {collation: {locale: "en", version: "unknownVersion"}}),
    ErrorCodes.IncompatibleCollationVersion);

// Ensure we can create a collection with the "simple" collation as the collection default.
assert.commandWorked(db.createCollection("collation", {collation: {locale: "simple"}}));
var collectionInfos = db.getCollectionInfos({name: "collation"});
assert.eq(collectionInfos.length, 1);
assert(!collectionInfos[0].options.hasOwnProperty("collation"));
coll.drop();

// Ensure that we populate all collation-related fields when we create a collection with a valid
// collation.
assert.commandWorked(db.createCollection("collation", {collation: {locale: "fr_CA"}}));
var collectionInfos = db.getCollectionInfos({name: "collation"});
assert.eq(collectionInfos.length, 1);
assert.eq(collectionInfos[0].options.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Ensure that an index with no collation inherits the collection-default collation.
assert.commandWorked(coll.ensureIndex({a: 1}));
assertIndexHasCollation({a: 1}, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Ensure that an index which specifies an overriding collation does not use the collection
// default.
assert.commandWorked(coll.ensureIndex({b: 1}, {collation: {locale: "en_US"}}));
assertIndexHasCollation({b: 1}, {
    locale: "en_US",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: false,
    version: "57.1",
});

// Ensure that an index which specifies the "simple" collation as an overriding collation still
// does not use the collection default.
assert.commandWorked(coll.ensureIndex({d: 1}, {collation: {locale: "simple"}}));
assertIndexHasCollation({d: 1}, {locale: "simple"});

// Ensure that a v=1 index doesn't inherit the collection-default collation.
assert.commandWorked(coll.ensureIndex({c: 1}, {v: 1}));
assertIndexHasCollation({c: 1}, {locale: "simple"});

// Test that all indexes retain their current collation when the collection is re-indexed.
if (!isMongos) {
    assert.commandWorked(coll.reIndex());
    assertIndexHasCollation({a: 1}, {
        locale: "fr_CA",
        caseLevel: false,
        caseFirst: "off",
        strength: 3,
        numericOrdering: false,
        alternate: "non-ignorable",
        maxVariable: "punct",
        normalization: false,
        backwards: true,
        version: "57.1",
    });
    assertIndexHasCollation({b: 1}, {
        locale: "en_US",
        caseLevel: false,
        caseFirst: "off",
        strength: 3,
        numericOrdering: false,
        alternate: "non-ignorable",
        maxVariable: "punct",
        normalization: false,
        backwards: false,
        version: "57.1",
    });
    assertIndexHasCollation({d: 1}, {locale: "simple"});
    assertIndexHasCollation({c: 1}, {locale: "simple"});
}

coll.drop();

//
// Creating an index with a collation.
//

// Attempting to build an index with an invalid collation should fail.
assert.commandFailed(coll.ensureIndex({a: 1}, {collation: "not an object"}));
assert.commandFailed(coll.ensureIndex({a: 1}, {collation: {}}));
assert.commandFailed(coll.ensureIndex({a: 1}, {collation: {blah: 1}}));
assert.commandFailed(coll.ensureIndex({a: 1}, {collation: {locale: "en", blah: 1}}));
assert.commandFailed(coll.ensureIndex({a: 1}, {collation: {locale: "xx"}}));
assert.commandFailed(coll.ensureIndex({a: 1}, {collation: {locale: "en", strength: 99}}));

// Attempting to create an index whose collation version does not match the collator version
// produced by ICU should result in failure with a special error code.
assert.commandFailedWithCode(
    coll.ensureIndex({a: 1}, {collation: {locale: "en", version: "unknownVersion"}}),
    ErrorCodes.IncompatibleCollationVersion);

assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "en_US"}}));
assertIndexHasCollation({a: 1}, {
    locale: "en_US",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: false,
    version: "57.1",
});

assert.commandWorked(coll.createIndex({b: 1}, {collation: {locale: "en_US"}}));
assertIndexHasCollation({b: 1}, {
    locale: "en_US",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: false,
    version: "57.1",
});

assert.commandWorked(coll.createIndexes([{c: 1}, {d: 1}], {collation: {locale: "fr_CA"}}));
assertIndexHasCollation({c: 1}, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});
assertIndexHasCollation({d: 1}, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

assert.commandWorked(coll.createIndexes([{e: 1}], {collation: {locale: "simple"}}));
assertIndexHasCollation({e: 1}, {locale: "simple"});

// Test that an index with a non-simple collation contains collator-generated comparison keys
// rather than the verbatim indexed strings.
if (db.getMongo().useReadCommands()) {
    coll.drop();
    assert.commandWorked(coll.createIndex({a: 1}, {collation: {locale: "fr_CA"}}));
    assert.commandWorked(coll.createIndex({b: 1}));
    assert.commandWorked(coll.insert({a: "foo", b: "foo"}));
    assert.eq(1, coll.find().collation({locale: "fr_CA"}).hint({a: 1}).returnKey().itcount());
    assert.neq("foo", coll.find().collation({locale: "fr_CA"}).hint({a: 1}).returnKey().next().a);
    assert.eq(1, coll.find().collation({locale: "fr_CA"}).hint({b: 1}).returnKey().itcount());
    assert.eq("foo", coll.find().collation({locale: "fr_CA"}).hint({b: 1}).returnKey().next().b);
}

// Test that a query with a string comparison can use an index with a non-simple collation if it
// has a matching collation.
if (db.getMongo().useReadCommands()) {
    coll.drop();
    assert.commandWorked(coll.createIndex({a: 1}, {collation: {locale: "fr_CA"}}));

    // Query has simple collation, but index has fr_CA collation.
    explainRes = coll.find({a: "foo"}).explain();
    assert.commandWorked(explainRes);
    assert(planHasStage(db, explainRes.queryPlanner.winningPlan, "COLLSCAN"));

    // Query has en_US collation, but index has fr_CA collation.
    explainRes = coll.find({a: "foo"}).collation({locale: "en_US"}).explain();
    assert.commandWorked(explainRes);
    assert(planHasStage(db, explainRes.queryPlanner.winningPlan, "COLLSCAN"));

    // Matching collations.
    explainRes = coll.find({a: "foo"}).collation({locale: "fr_CA"}).explain();
    assert.commandWorked(explainRes);
    assert(planHasStage(db, explainRes.queryPlanner.winningPlan, "IXSCAN"));
}

// Should not be possible to create a text index with an explicit non-simple collation.
coll.drop();
assert.commandFailed(coll.createIndex({a: "text"}, {collation: {locale: "en"}}));

// Text index builds which inherit a non-simple default collation should fail.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en"}}));
assert.commandFailed(coll.createIndex({a: "text"}));

// Text index build should succeed on a collection with a non-simple default collation if it
// explicitly overrides the default with {locale: "simple"}.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en"}}));
assert.commandWorked(coll.createIndex({a: "text"}, {collation: {locale: "simple"}}));

//
// Collation tests for aggregation.
//

// Aggregation should return correct results when collation specified and collection does not
// exist.
coll.drop();
assert.eq(0, coll.aggregate([], {collation: {locale: "fr"}}).itcount());

// Aggregation should return correct results when collation specified and collection does exist.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
assert.eq(0, coll.aggregate([{$match: {str: "FOO"}}]).itcount());
assert.eq(1,
          coll.aggregate([{$match: {str: "FOO"}}], {collation: {locale: "en_US", strength: 2}})
              .itcount());

// Aggregation should return correct results when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.eq(1, coll.aggregate([{$match: {str: "FOO"}}]).itcount());

// Aggregation should return correct results when "simple" collation specified and collection
// has a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.eq(0, coll.aggregate([{$match: {str: "FOO"}}], {collation: {locale: "simple"}}).itcount());

// Aggregation should select compatible index when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "en_US"}}));
var explain = coll.explain("queryPlanner").aggregate([{$match: {a: "foo"}}]);
assert(isIxscan(db, explain.queryPlanner.winningPlan));

// Aggregation should not use index when no collation specified and collection default
// collation is incompatible with index collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "simple"}}));
var explain = coll.explain("queryPlanner").aggregate([{$match: {a: "foo"}}]);
assert(isCollscan(db, explain.queryPlanner.winningPlan));

// Explain of aggregation with collation should succeed.
assert.commandWorked(coll.explain().aggregate([], {collation: {locale: "fr"}}));

//
// Collation tests for count.
//

// Count should return correct results when collation specified and collection does not exist.
coll.drop();
assert.eq(0, coll.find({str: "FOO"}).collation({locale: "en_US"}).count());

// Count should return correct results when collation specified and collection does exist.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
assert.eq(0, coll.find({str: "FOO"}).count());
assert.eq(0, coll.find({str: "FOO"}).collation({locale: "en_US"}).count());
assert.eq(1, coll.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).count());
assert.eq(0, coll.count({str: "FOO"}));
assert.eq(0, coll.count({str: "FOO"}, {collation: {locale: "en_US"}}));
assert.eq(1, coll.count({str: "FOO"}, {collation: {locale: "en_US", strength: 2}}));

// Count should return correct results when no collation specified and collection has a default
// collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.eq(1, coll.find({str: "FOO"}).count());

// Count should return correct results when "simple" collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.eq(0, coll.find({str: "FOO"}).collation({locale: "simple"}).count());

// Count should return correct results when collation specified and when run with explain.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
explainRes = coll.explain("executionStats").find({str: "FOO"}).collation({locale: "en_US"}).count();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "COLLSCAN");
assert.neq(null, planStage);
assert.eq(0, planStage.advanced);
explainRes = coll.explain("executionStats")
                 .find({str: "FOO"})
                 .collation({locale: "en_US", strength: 2})
                 .count();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "COLLSCAN");
assert.neq(null, planStage);
assert.eq(1, planStage.advanced);

// Explain of COUNT_SCAN stage should include index collation.
coll.drop();
assert.commandWorked(coll.createIndex({a: 1}, {collation: {locale: "fr_CA"}}));
explainRes = coll.explain("executionStats").find({a: 5}).count();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "COUNT_SCAN");
assert.neq(null, planStage);
assert.eq(planStage.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Explain of COUNT_SCAN stage should include index collation when index collation is
// inherited from collection default.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "fr_CA"}}));
assert.commandWorked(coll.createIndex({a: 1}));
explainRes = coll.explain("executionStats").find({a: 5}).count();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "COUNT_SCAN");
assert.neq(null, planStage);
assert.eq(planStage.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Should be able to use COUNT_SCAN for queries over strings.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "fr_CA"}}));
assert.commandWorked(coll.createIndex({a: 1}));
explainRes = coll.explain("executionStats").find({a: "foo"}).count();
assert.commandWorked(explainRes);
assert(planHasStage(db, explainRes.executionStats.executionStages, "COUNT_SCAN"));
assert(!planHasStage(db, explainRes.executionStats.executionStages, "FETCH"));

//
// Collation tests for distinct.
//

// Distinct should return correct results when collation specified and collection does not
// exist.
coll.drop();
assert.eq(0, coll.distinct("str", {}, {collation: {locale: "en_US", strength: 2}}).length);

// Distinct should return correct results when collation specified and no indexes exist.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "FOO"}));
var res = coll.distinct("str", {}, {collation: {locale: "en_US", strength: 2}});
assert.eq(1, res.length);
assert.eq("foo", res[0].toLowerCase());
assert.eq(2, coll.distinct("str", {}, {collation: {locale: "en_US", strength: 3}}).length);
assert.eq(2,
          coll.distinct("_id", {str: "foo"}, {collation: {locale: "en_US", strength: 2}}).length);

// Distinct should return correct results when collation specified and compatible index exists.
coll.createIndex({str: 1}, {collation: {locale: "en_US", strength: 2}});
res = coll.distinct("str", {}, {collation: {locale: "en_US", strength: 2}});
assert.eq(1, res.length);
assert.eq("foo", res[0].toLowerCase());
assert.eq(2, coll.distinct("str", {}, {collation: {locale: "en_US", strength: 3}}).length);

// Distinct should return correct results when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.commandWorked(coll.insert({str: "FOO"}));
assert.eq(1, coll.distinct("str").length);
assert.eq(2, coll.distinct("_id", {str: "foo"}).length);

// Distinct should return correct results when "simple" collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.commandWorked(coll.insert({str: "FOO"}));
assert.eq(2, coll.distinct("str", {}, {collation: {locale: "simple"}}).length);
assert.eq(1, coll.distinct("_id", {str: "foo"}, {collation: {locale: "simple"}}).length);

// Distinct should select compatible index when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "en_US"}}));
var explain = coll.explain("queryPlanner").distinct("a");
assert(planHasStage(db, explain.queryPlanner.winningPlan, "DISTINCT_SCAN"));
assert(planHasStage(db, explain.queryPlanner.winningPlan, "FETCH"));

// Distinct scan on strings can be used over an index with a collation when the predicate has
// exact bounds.
explain = coll.explain("queryPlanner").distinct("a", {a: {$gt: "foo"}});
assert(planHasStage(db, explain.queryPlanner.winningPlan, "DISTINCT_SCAN"));
assert(planHasStage(db, explain.queryPlanner.winningPlan, "FETCH"));
assert(!planHasStage(db, explain.queryPlanner.winningPlan, "PROJECTION_COVERED"));

// Distinct scan cannot be used over an index with a collation when the predicate has inexact
// bounds.
explain = coll.explain("queryPlanner").distinct("a", {a: {$exists: true}});
assert(planHasStage(db, explain.queryPlanner.winningPlan, "IXSCAN"));
assert(planHasStage(db, explain.queryPlanner.winningPlan, "FETCH"));
assert(!planHasStage(db, explain.queryPlanner.winningPlan, "DISTINCT_SCAN"));

// Distinct scan can be used without a fetch when predicate has exact non-string bounds.
explain = coll.explain("queryPlanner").distinct("a", {a: {$gt: 3}});
assert(planHasStage(db, explain.queryPlanner.winningPlan, "DISTINCT_SCAN"));
assert(planHasStage(db, explain.queryPlanner.winningPlan, "PROJECTION_COVERED"));
assert(!planHasStage(db, explain.queryPlanner.winningPlan, "FETCH"));

// Distinct should not use index when no collation specified and collection default collation is
// incompatible with index collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "simple"}}));
var explain = coll.explain("queryPlanner").distinct("a");
assert(isCollscan(db, explain.queryPlanner.winningPlan));

// Explain of DISTINCT_SCAN stage should include index collation.
coll.drop();
assert.commandWorked(coll.createIndex({str: 1}, {collation: {locale: "fr_CA"}}));
explainRes = coll.explain("executionStats").distinct("str", {}, {collation: {locale: "fr_CA"}});
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "DISTINCT_SCAN");
assert.neq(null, planStage);
assert.eq(planStage.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Explain of DISTINCT_SCAN stage should include index collation when index collation is
// inherited from collection default.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "fr_CA"}}));
assert.commandWorked(coll.createIndex({str: 1}));
explainRes = coll.explain("executionStats").distinct("str");
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "DISTINCT_SCAN");
assert.neq(null, planStage);
assert.eq(planStage.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

//
// Collation tests for find.
//

if (db.getMongo().useReadCommands()) {
    // Find should return correct results when collation specified and collection does not
    // exist.
    coll.drop();
    assert.eq(0, coll.find({_id: "FOO"}).collation({locale: "en_US"}).itcount());

    // Find should return correct results when collation specified and filter is a match on _id.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
    assert.commandWorked(coll.insert({_id: "foo"}));
    assert.eq(0, coll.find({_id: "FOO"}).itcount());
    assert.eq(0, coll.find({_id: "FOO"}).collation({locale: "en_US"}).itcount());
    assert.eq(1, coll.find({_id: "FOO"}).collation({locale: "en_US", strength: 2}).itcount());
    assert.commandWorked(coll.remove({_id: "foo"}));

    // Find should return correct results when collation specified and no indexes exist.
    assert.eq(0, coll.find({str: "FOO"}).itcount());
    assert.eq(0, coll.find({str: "FOO"}).collation({locale: "en_US"}).itcount());
    assert.eq(1, coll.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).itcount());
    assert.eq(1,
              coll.find({str: {$ne: "FOO"}}).collation({locale: "en_US", strength: 2}).itcount());

    // Find should return correct results when collation specified and compatible index exists.
    assert.commandWorked(coll.ensureIndex({str: 1}, {collation: {locale: "en_US", strength: 2}}));
    assert.eq(0, coll.find({str: "FOO"}).hint({str: 1}).itcount());
    assert.eq(0, coll.find({str: "FOO"}).collation({locale: "en_US"}).hint({str: 1}).itcount());
    assert.eq(
        1,
        coll.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).hint({str: 1}).itcount());
    assert.eq(1,
              coll.find({str: {$ne: "FOO"}})
                  .collation({locale: "en_US", strength: 2})
                  .hint({str: 1})
                  .itcount());
    assert.commandWorked(coll.dropIndexes());

    // Find should return correct results when collation specified and compatible partial index
    // exists.
    assert.commandWorked(coll.ensureIndex({str: 1}, {
        partialFilterExpression: {str: {$lte: "FOO"}},
        collation: {locale: "en_US", strength: 2}
    }));
    assert.eq(
        1,
        coll.find({str: "foo"}).collation({locale: "en_US", strength: 2}).hint({str: 1}).itcount());
    assert.commandWorked(coll.insert({_id: 3, str: "goo"}));
    assert.eq(
        0,
        coll.find({str: "goo"}).collation({locale: "en_US", strength: 2}).hint({str: 1}).itcount());
    assert.commandWorked(coll.remove({_id: 3}));
    assert.commandWorked(coll.dropIndexes());

    // Queries that use a index with a non-matching collation should add a sort
    // stage if needed.
    coll.drop();
    assert.commandWorked(coll.insert([{a: "A"}, {a: "B"}, {a: "b"}, {a: "a"}]));

    // Ensure results from an index that doesn't match the query collation are sorted to match
    // the requested collation.
    assert.commandWorked(coll.ensureIndex({a: 1}));
    var res =
        coll.find({a: {'$exists': true}}, {_id: 0}).collation({locale: "en_US", strength: 3}).sort({
            a: 1
        });
    assert.eq(res.toArray(), [{a: "a"}, {a: "A"}, {a: "b"}, {a: "B"}]);

    // Find should return correct results when collation specified and query contains $expr.
    coll.drop();
    assert.commandWorked(coll.insert([{a: "A"}, {a: "B"}]));
    assert.eq(
        1,
        coll.find({$expr: {$eq: ["$a", "a"]}}).collation({locale: "en_US", strength: 2}).itcount());
}

// Find should return correct results when no collation specified and collection has a default
// collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({str: "foo"}));
assert.commandWorked(coll.insert({str: "FOO"}));
assert.commandWorked(coll.insert({str: "bar"}));
assert.eq(3, coll.find({str: {$in: ["foo", "bar"]}}).itcount());
assert.eq(2, coll.find({str: "foo"}).itcount());
assert.eq(1, coll.find({str: {$ne: "foo"}}).itcount());
assert.eq([{str: "bar"}, {str: "foo"}, {str: "FOO"}],
          coll.find({}, {_id: 0, str: 1}).sort({str: 1}).toArray());

// Find with idhack should return correct results when no collation specified and collection has
// a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: "foo"}));
assert.eq(1, coll.find({_id: "FOO"}).itcount());

// Find on _id should use idhack stage when query inherits collection default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
explainRes = coll.explain("executionStats").find({_id: "foo"}).finish();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
assert.neq(null, planStage);

// Find should return correct results for query containing $expr when no collation specified and
// collection has a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert([{a: "A"}, {a: "B"}]));
assert.eq(1, coll.find({$expr: {$eq: ["$a", "a"]}}).itcount());

if (db.getMongo().useReadCommands()) {
    // Find should return correct results when "simple" collation specified and collection has a
    // default collation.
    coll.drop();
    assert.commandWorked(
        db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
    assert.commandWorked(coll.insert({str: "foo"}));
    assert.commandWorked(coll.insert({str: "FOO"}));
    assert.commandWorked(coll.insert({str: "bar"}));
    assert.eq(2, coll.find({str: {$in: ["foo", "bar"]}}).collation({locale: "simple"}).itcount());
    assert.eq(1, coll.find({str: "foo"}).collation({locale: "simple"}).itcount());
    assert.eq(
        [{str: "FOO"}, {str: "bar"}, {str: "foo"}],
        coll.find({}, {_id: 0, str: 1}).sort({str: 1}).collation({locale: "simple"}).toArray());

    // Find on _id should return correct results when query collation differs from collection
    // default collation.
    coll.drop();
    assert.commandWorked(
        db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 3}}));
    assert.commandWorked(coll.insert({_id: "foo"}));
    assert.commandWorked(coll.insert({_id: "FOO"}));
    assert.eq(2, coll.find({_id: "foo"}).collation({locale: "en_US", strength: 2}).itcount());

    // Find on _id should use idhack stage when explicitly given query collation matches
    // collection default.
    coll.drop();
    assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
    explainRes =
        coll.explain("executionStats").find({_id: "foo"}).collation({locale: "en_US"}).finish();
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
    assert.neq(null, planStage);

    // Find on _id should not use idhack stage when query collation does not match collection
    // default.
    coll.drop();
    assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
    explainRes =
        coll.explain("executionStats").find({_id: "foo"}).collation({locale: "fr_CA"}).finish();
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
    assert.eq(null, planStage);
}

// Find should select compatible index when no collation specified and collection has a default
// collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "en_US"}}));
var explain = coll.find({a: "foo"}).explain("queryPlanner");
assert(isIxscan(db, explain.queryPlanner.winningPlan));

// Find should select compatible index when no collation specified and collection default
// collation is "simple".
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "simple"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "simple"}}));
var explain = coll.find({a: "foo"}).explain("queryPlanner");
assert(isIxscan(db, explain.queryPlanner.winningPlan));

// Find should not use index when no collation specified, index collation is "simple", and
// collection has a non-"simple" default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "simple"}}));
var explain = coll.find({a: "foo"}).explain("queryPlanner");
assert(isCollscan(db, explain.queryPlanner.winningPlan));

// Find should select compatible index when "simple" collation specified and collection has a
// non-"simple" default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
assert.commandWorked(coll.ensureIndex({a: 1}, {collation: {locale: "simple"}}));
var explain = coll.find({a: "foo"}).collation({locale: "simple"}).explain("queryPlanner");
assert(isIxscan(db, explain.queryPlanner.winningPlan));

// Find should return correct results when collation specified and run with explain.
coll.drop();
assert.commandWorked(coll.insert({str: "foo"}));
explainRes =
    coll.explain("executionStats").find({str: "FOO"}).collation({locale: "en_US"}).finish();
assert.commandWorked(explainRes);
assert.eq(0, explainRes.executionStats.nReturned);
explainRes = coll.explain("executionStats")
                 .find({str: "FOO"})
                 .collation({locale: "en_US", strength: 2})
                 .finish();
assert.commandWorked(explainRes);
assert.eq(1, explainRes.executionStats.nReturned);

// Explain of find should include query collation.
coll.drop();
explainRes =
    coll.explain("executionStats").find({str: "foo"}).collation({locale: "fr_CA"}).finish();
assert.commandWorked(explainRes);
assert.eq(getQueryCollation(explainRes), {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Explain of find should include query collation when inherited from collection default.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "fr_CA"}}));
explainRes = coll.explain("executionStats").find({str: "foo"}).finish();
assert.commandWorked(explainRes);
assert.eq(getQueryCollation(explainRes), {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Explain of IXSCAN stage should include index collation.
coll.drop();
assert.commandWorked(coll.createIndex({str: 1}, {collation: {locale: "fr_CA"}}));
explainRes =
    coll.explain("executionStats").find({str: "foo"}).collation({locale: "fr_CA"}).finish();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "IXSCAN");
assert.neq(null, planStage);
assert.eq(planStage.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

// Explain of IXSCAN stage should include index collation when index collation is inherited from
// collection default.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "fr_CA"}}));
assert.commandWorked(coll.createIndex({str: 1}));
explainRes = coll.explain("executionStats").find({str: "foo"}).finish();
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "IXSCAN");
assert.neq(null, planStage);
assert.eq(planStage.collation, {
    locale: "fr_CA",
    caseLevel: false,
    caseFirst: "off",
    strength: 3,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: true,
    version: "57.1",
});

if (!db.getMongo().useReadCommands()) {
    // find() shell helper should error if a collation is specified and the shell is not using
    // read commands.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
    assert.throws(function() {
        coll.find().collation({locale: "fr"}).itcount();
    });
}

//
// Collation tests for findAndModify.
//

// findAndModify should return correct results when collation specified and collection does not
// exist.
coll.drop();
assert.eq(
    null,
    coll.findAndModify(
        {query: {str: "bar"}, update: {$set: {str: "baz"}}, new: true, collation: {locale: "fr"}}));

// Update-findAndModify should return correct results when collation specified.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
assert.eq({_id: 1, str: "baz"}, coll.findAndModify({
    query: {str: "FOO"},
    update: {$set: {str: "baz"}},
    new: true,
    collation: {locale: "en_US", strength: 2}
}));

// Explain of update-findAndModify should return correct results when collation specified.
explainRes = coll.explain("executionStats").findAndModify({
    query: {str: "BAR"},
    update: {$set: {str: "baz"}},
    new: true,
    collation: {locale: "en_US", strength: 2}
});
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "UPDATE");
assert.neq(null, planStage);
assert.eq(1, planStage.nWouldModify);

// Delete-findAndModify should return correct results when collation specified.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
assert.eq({_id: 1, str: "foo"},
          coll.findAndModify(
              {query: {str: "FOO"}, remove: true, collation: {locale: "en_US", strength: 2}}));

// Explain of delete-findAndModify should return correct results when collation specified.
explainRes = coll.explain("executionStats").findAndModify({
    query: {str: "BAR"},
    remove: true,
    collation: {locale: "en_US", strength: 2}
});
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "DELETE");
assert.neq(null, planStage);
assert.eq(1, planStage.nWouldDelete);

// findAndModify should return correct results when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.eq({_id: 1, str: "foo"}, coll.findAndModify({query: {str: "FOO"}, update: {$set: {x: 1}}}));
assert.eq({_id: 1, str: "foo", x: 1}, coll.findAndModify({query: {str: "FOO"}, remove: true}));

// findAndModify should return correct results when "simple" collation specified and collection
// has a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.eq(null,
          coll.findAndModify(
              {query: {str: "FOO"}, update: {$set: {x: 1}}, collation: {locale: "simple"}}));
assert.eq(null,
          coll.findAndModify({query: {str: "FOO"}, remove: true, collation: {locale: "simple"}}));

//
// Collation tests for mapReduce.
//

// mapReduce should return correct results when collation specified and no indexes exist.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
var mapReduceOut = coll.mapReduce(
    function() {
        emit(this.str, 1);
    },
    function(key, values) {
        return Array.sum(values);
    },
    {out: {inline: 1}, query: {str: "FOO"}, collation: {locale: "en_US", strength: 2}});
assert.commandWorked(mapReduceOut);
assert.eq(mapReduceOut.results.length, 1);

// mapReduce should return correct results when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
var mapReduceOut = coll.mapReduce(
    function() {
        emit(this.str, 1);
    },
    function(key, values) {
        return Array.sum(values);
    },
    {out: {inline: 1}, query: {str: "FOO"}});
assert.commandWorked(mapReduceOut);
assert.eq(mapReduceOut.results.length, 1);

// mapReduce should return correct results when "simple" collation specified and collection has
// a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
var mapReduceOut = coll.mapReduce(
    function() {
        emit(this.str, 1);
    },
    function(key, values) {
        return Array.sum(values);
    },
    {out: {inline: 1}, query: {str: "FOO"}, collation: {locale: "simple"}});
assert.commandWorked(mapReduceOut);
assert.eq(mapReduceOut.results.length, 0);

//
// Collation tests for remove.
//

if (db.getMongo().writeMode() === "commands") {
    // Remove should succeed when collation specified and collection does not exist.
    coll.drop();
    assert.commandWorked(coll.remove({str: "foo"}, {justOne: true, collation: {locale: "fr"}}));

    // Remove should return correct results when collation specified.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    writeRes =
        coll.remove({str: "FOO"}, {justOne: true, collation: {locale: "en_US", strength: 2}});
    assert.commandWorked(writeRes);
    assert.eq(1, writeRes.nRemoved);

    // Explain of remove should return correct results when collation specified.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    explainRes = coll.explain("executionStats").remove({str: "FOO"}, {
        justOne: true,
        collation: {locale: "en_US", strength: 2}
    });
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "DELETE");
    assert.neq(null, planStage);
    assert.eq(1, planStage.nWouldDelete);
}

// Remove should return correct results when no collation specified and collection has a default
// collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
writeRes = coll.remove({str: "FOO"}, {justOne: true});
assert.commandWorked(writeRes);
assert.eq(1, writeRes.nRemoved);

// Remove with idhack should return correct results when no collation specified and collection
// has a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: "foo"}));
writeRes = coll.remove({_id: "FOO"}, {justOne: true});
assert.commandWorked(writeRes);
assert.eq(1, writeRes.nRemoved);

// Remove on _id should use idhack stage when query inherits collection default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
explainRes = coll.explain("executionStats").remove({_id: "foo"});
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
assert.neq(null, planStage);

if (db.getMongo().writeMode() === "commands") {
    // Remove should return correct results when "simple" collation specified and collection has
    // a default collation.
    coll.drop();
    assert.commandWorked(
        db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    writeRes = coll.remove({str: "FOO"}, {justOne: true, collation: {locale: "simple"}});
    assert.commandWorked(writeRes);
    assert.eq(0, writeRes.nRemoved);

    // Remove on _id should return correct results when "simple" collation specified and
    // collection has a default collation.
    coll.drop();
    assert.commandWorked(
        db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
    assert.commandWorked(coll.insert({_id: "foo"}));
    writeRes = coll.remove({_id: "FOO"}, {justOne: true, collation: {locale: "simple"}});
    assert.commandWorked(writeRes);
    assert.eq(0, writeRes.nRemoved);

    // Remove on _id should use idhack stage when explicit query collation matches collection
    // default.
    coll.drop();
    assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
    explainRes =
        coll.explain("executionStats").remove({_id: "foo"}, {collation: {locale: "en_US"}});
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
    assert.neq(null, planStage);

    // Remove on _id should not use idhack stage when query collation does not match collection
    // default.
    coll.drop();
    assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
    explainRes =
        coll.explain("executionStats").remove({_id: "foo"}, {collation: {locale: "fr_CA"}});
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
    assert.eq(null, planStage);
}

if (db.getMongo().writeMode() !== "commands") {
    // remove() shell helper should error if a collation is specified and the shell is not using
    // write commands.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    assert.throws(function() {
        coll.remove({str: "FOO"}, {justOne: true, collation: {locale: "en_US", strength: 2}});
    });
    assert.throws(function() {
        coll.explain().remove({str: "FOO"},
                              {justOne: true, collation: {locale: "en_US", strength: 2}});
    });
}

//
// Collation tests for update.
//

if (db.getMongo().writeMode() === "commands") {
    // Update should succeed when collation specified and collection does not exist.
    coll.drop();
    assert.commandWorked(
        coll.update({str: "foo"}, {$set: {other: 99}}, {multi: true, collation: {locale: "fr"}}));

    // Update should return correct results when collation specified.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    writeRes = coll.update({str: "FOO"},
                           {$set: {other: 99}},
                           {multi: true, collation: {locale: "en_US", strength: 2}});
    assert.eq(2, writeRes.nModified);

    // Explain of update should return correct results when collation specified.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    explainRes = coll.explain("executionStats").update({str: "FOO"}, {$set: {other: 99}}, {
        multi: true,
        collation: {locale: "en_US", strength: 2}
    });
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "UPDATE");
    assert.neq(null, planStage);
    assert.eq(2, planStage.nWouldModify);
}

// Update should return correct results when no collation specified and collection has a default
// collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
writeRes = coll.update({str: "FOO"}, {$set: {other: 99}});
assert.commandWorked(writeRes);
assert.eq(1, writeRes.nMatched);

// Update with idhack should return correct results when no collation specified and collection
// has a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.insert({_id: "foo"}));
writeRes = coll.update({_id: "FOO"}, {$set: {other: 99}});
assert.commandWorked(writeRes);
assert.eq(1, writeRes.nMatched);

// Update on _id should use idhack stage when query inherits collection default collation.
coll.drop();
assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
explainRes = coll.explain("executionStats").update({_id: "foo"}, {$set: {other: 99}});
assert.commandWorked(explainRes);
planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
assert.neq(null, planStage);

if (db.getMongo().writeMode() === "commands") {
    // Update should return correct results when "simple" collation specified and collection has
    // a default collation.
    coll.drop();
    assert.commandWorked(
        db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    writeRes = coll.update({str: "FOO"}, {$set: {other: 99}}, {collation: {locale: "simple"}});
    assert.commandWorked(writeRes);
    assert.eq(0, writeRes.nModified);

    // Update on _id should return correct results when "simple" collation specified and
    // collection has a default collation.
    coll.drop();
    assert.commandWorked(
        db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
    assert.commandWorked(coll.insert({_id: "foo"}));
    writeRes = coll.update({_id: "FOO"}, {$set: {other: 99}}, {collation: {locale: "simple"}});
    assert.commandWorked(writeRes);
    assert.eq(0, writeRes.nModified);

    // Update on _id should use idhack stage when explicitly given query collation matches
    // collection default.
    coll.drop();
    assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
    explainRes = coll.explain("executionStats").update({_id: "foo"}, {$set: {other: 99}}, {
        collation: {locale: "en_US"}
    });
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
    assert.neq(null, planStage);

    // Update on _id should not use idhack stage when query collation does not match collection
    // default.
    coll.drop();
    assert.commandWorked(db.createCollection(coll.getName(), {collation: {locale: "en_US"}}));
    explainRes = coll.explain("executionStats").update({_id: "foo"}, {$set: {other: 99}}, {
        collation: {locale: "fr_CA"}
    });
    assert.commandWorked(explainRes);
    planStage = getPlanStage(explainRes.executionStats.executionStages, "IDHACK");
    assert.eq(null, planStage);
}

if (db.getMongo().writeMode() !== "commands") {
    // update() shell helper should error if a collation is specified and the shell is not using
    // write commands.
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    assert.throws(function() {
        coll.update({str: "FOO"},
                    {$set: {other: 99}},
                    {multi: true, collation: {locale: "en_US", strength: 2}});
    });
    assert.throws(function() {
        coll.explain().update({str: "FOO"},
                              {$set: {other: 99}},
                              {multi: true, collation: {locale: "en_US", strength: 2}});
    });
}

//
// Collation tests for the $geoNear aggregation stage.
//

// $geoNear should fail when collation is specified but the collection does not exist.
coll.drop();
assert.commandFailedWithCode(db.runCommand({
    aggregate: coll.getName(),
    cursor: {},
    pipeline: [{
        $geoNear: {
            near: {type: "Point", coordinates: [0, 0]},
            distanceField: "dist",
        }
    }],
    collation: {locale: "en_US", strength: 2}
}),
                             ErrorCodes.NamespaceNotFound);

// $geoNear rejects the now-deprecated "collation" option.
coll.drop();
assert.commandWorked(coll.insert({geo: {type: "Point", coordinates: [0, 0]}, str: "abc"}));
assert.commandFailedWithCode(db.runCommand({
    aggregate: coll.getName(),
    cursor: {},
    pipeline: [{
        $geoNear: {
            near: {type: "Point", coordinates: [0, 0]},
            distanceField: "dist",
            collation: {locale: "en_US"},
        }
    }],
}),
                             40227);

const geoNearStage = {
    $geoNear: {
        near: {type: "Point", coordinates: [0, 0]},
        distanceField: "dist",
        spherical: true,
        query: {str: "ABC"}
    }
};

// $geoNear should return correct results when collation specified and string predicate not
// indexed.
assert.commandWorked(coll.ensureIndex({geo: "2dsphere"}));
assert.eq(0, coll.aggregate([geoNearStage]).itcount());
assert.eq(1, coll.aggregate([geoNearStage], {collation: {locale: "en_US", strength: 2}}).itcount());

// $geoNear should return correct results when no collation specified and string predicate
// indexed.
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(coll.ensureIndex({geo: "2dsphere", str: 1}));
assert.eq(0, coll.aggregate([geoNearStage]).itcount());
assert.eq(1, coll.aggregate([geoNearStage], {collation: {locale: "en_US", strength: 2}}).itcount());

// $geoNear should return correct results when collation specified and collation on index is
// incompatible with string predicate.
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(
    coll.ensureIndex({geo: "2dsphere", str: 1}, {collation: {locale: "en_US", strength: 3}}));
assert.eq(0, coll.aggregate([geoNearStage]).itcount());
assert.eq(1, coll.aggregate([geoNearStage], {collation: {locale: "en_US", strength: 2}}).itcount());

// $geoNear should return correct results when collation specified and collation on index is
// compatible with string predicate.
assert.commandWorked(coll.dropIndexes());
assert.commandWorked(
    coll.ensureIndex({geo: "2dsphere", str: 1}, {collation: {locale: "en_US", strength: 2}}));
assert.eq(0, coll.aggregate([geoNearStage]).itcount());
assert.eq(1, coll.aggregate([geoNearStage], {collation: {locale: "en_US", strength: 2}}).itcount());

// $geoNear should return correct results when no collation specified and collection has a
// default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.ensureIndex({geo: "2dsphere"}));
assert.commandWorked(coll.insert({geo: {type: "Point", coordinates: [0, 0]}, str: "abc"}));
assert.eq(1, coll.aggregate([geoNearStage]).itcount());

// $geoNear should return correct results when "simple" collation specified and collection has
// a default collation.
coll.drop();
assert.commandWorked(
    db.createCollection(coll.getName(), {collation: {locale: "en_US", strength: 2}}));
assert.commandWorked(coll.ensureIndex({geo: "2dsphere"}));
assert.commandWorked(coll.insert({geo: {type: "Point", coordinates: [0, 0]}, str: "abc"}));
assert.eq(0, coll.aggregate([geoNearStage], {collation: {locale: "simple"}}).itcount());

//
// Collation tests for find with $nearSphere.
//

if (db.getMongo().useReadCommands()) {
    // Find with $nearSphere should return correct results when collation specified and
    // collection does not exist.
    coll.drop();
    assert.eq(
        0,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .collation({locale: "en_US", strength: 2})
            .itcount());

    // Find with $nearSphere should return correct results when collation specified and string
    // predicate not indexed.
    coll.drop();
    assert.commandWorked(coll.insert({geo: {type: "Point", coordinates: [0, 0]}, str: "abc"}));
    assert.commandWorked(coll.ensureIndex({geo: "2dsphere"}));
    assert.eq(
        0,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .itcount());
    assert.eq(
        1,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .collation({locale: "en_US", strength: 2})
            .itcount());

    // Find with $nearSphere should return correct results when no collation specified and
    // string predicate indexed.
    assert.commandWorked(coll.dropIndexes());
    assert.commandWorked(coll.ensureIndex({geo: "2dsphere", str: 1}));
    assert.eq(
        0,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .itcount());
    assert.eq(
        1,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .collation({locale: "en_US", strength: 2})
            .itcount());

    // Find with $nearSphere should return correct results when collation specified and
    // collation on index is incompatible with string predicate.
    assert.commandWorked(coll.dropIndexes());
    assert.commandWorked(
        coll.ensureIndex({geo: "2dsphere", str: 1}, {collation: {locale: "en_US", strength: 3}}));
    assert.eq(
        0,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .itcount());
    assert.eq(
        1,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .collation({locale: "en_US", strength: 2})
            .itcount());

    // Find with $nearSphere should return correct results when collation specified and
    // collation on index is compatible with string predicate.
    assert.commandWorked(coll.dropIndexes());
    assert.commandWorked(
        coll.ensureIndex({geo: "2dsphere", str: 1}, {collation: {locale: "en_US", strength: 2}}));
    assert.eq(
        0,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .itcount());
    assert.eq(
        1,
        coll.find(
                {str: "ABC", geo: {$nearSphere: {$geometry: {type: "Point", coordinates: [0, 0]}}}})
            .collation({locale: "en_US", strength: 2})
            .itcount());
}

//
// Tests for the bulk API.
//

var bulk;

if (db.getMongo().writeMode() !== "commands") {
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));

    // Can't use the bulk API to set a collation when using legacy write ops.
    bulk = coll.initializeUnorderedBulkOp();
    assert.throws(function() {
        bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2});
    });

    bulk = coll.initializeOrderedBulkOp();
    assert.throws(function() {
        bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2});
    });
} else {
    // update().
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).update({$set: {other: 99}});
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(2, writeRes.nModified);

    // updateOne().
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).updateOne({
        $set: {other: 99}
    });
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(1, writeRes.nModified);

    // replaceOne().
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).replaceOne({str: "oof"});
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(1, writeRes.nModified);

    // replaceOne() with upsert().
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US"}).upsert().replaceOne({str: "foo"});
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(1, writeRes.nUpserted);
    assert.eq(0, writeRes.nModified);

    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).upsert().replaceOne({
        str: "foo"
    });
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(0, writeRes.nUpserted);
    assert.eq(1, writeRes.nModified);

    // removeOne().
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).removeOne();
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(1, writeRes.nRemoved);

    // remove().
    coll.drop();
    assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
    assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
    bulk = coll.initializeUnorderedBulkOp();
    bulk.find({str: "FOO"}).collation({locale: "en_US", strength: 2}).remove();
    writeRes = bulk.execute();
    assert.commandWorked(writeRes);
    assert.eq(2, writeRes.nRemoved);
}

//
// Tests for the CRUD API.
//

// deleteOne().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.deleteOne({str: "FOO"}, {collation: {locale: "en_US", strength: 2}});
    assert.eq(1, res.deletedCount);
} else {
    assert.throws(function() {
        coll.deleteOne({str: "FOO"}, {collation: {locale: "en_US", strength: 2}});
    });
}

// deleteMany().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.deleteMany({str: "FOO"}, {collation: {locale: "en_US", strength: 2}});
    assert.eq(2, res.deletedCount);
} else {
    assert.throws(function() {
        coll.deleteMany({str: "FOO"}, {collation: {locale: "en_US", strength: 2}});
    });
}

// findOneAndDelete().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.eq({_id: 1, str: "foo"},
          coll.findOneAndDelete({str: "FOO"}, {collation: {locale: "en_US", strength: 2}}));
assert.eq(null, coll.findOne({_id: 1}));

// findOneAndReplace().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.eq({_id: 1, str: "foo"},
          coll.findOneAndReplace(
              {str: "FOO"}, {str: "bar"}, {collation: {locale: "en_US", strength: 2}}));
assert.neq(null, coll.findOne({str: "bar"}));

// findOneAndUpdate().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.eq({_id: 1, str: "foo"},
          coll.findOneAndUpdate(
              {str: "FOO"}, {$set: {other: 99}}, {collation: {locale: "en_US", strength: 2}}));
assert.neq(null, coll.findOne({other: 99}));

// replaceOne().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res =
        coll.replaceOne({str: "FOO"}, {str: "bar"}, {collation: {locale: "en_US", strength: 2}});
    assert.eq(1, res.modifiedCount);
} else {
    assert.throws(function() {
        coll.replaceOne({str: "FOO"}, {str: "bar"}, {collation: {locale: "en_US", strength: 2}});
    });
}

// updateOne().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.updateOne(
        {str: "FOO"}, {$set: {other: 99}}, {collation: {locale: "en_US", strength: 2}});
    assert.eq(1, res.modifiedCount);
} else {
    assert.throws(function() {
        coll.updateOne(
            {str: "FOO"}, {$set: {other: 99}}, {collation: {locale: "en_US", strength: 2}});
    });
}

// updateMany().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.updateMany(
        {str: "FOO"}, {$set: {other: 99}}, {collation: {locale: "en_US", strength: 2}});
    assert.eq(2, res.modifiedCount);
} else {
    assert.throws(function() {
        coll.updateMany(
            {str: "FOO"}, {$set: {other: 99}}, {collation: {locale: "en_US", strength: 2}});
    });
}

// updateOne with bulkWrite().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.bulkWrite([{
        updateOne: {
            filter: {str: "FOO"},
            update: {$set: {other: 99}},
            collation: {locale: "en_US", strength: 2}
        }
    }]);
    assert.eq(1, res.matchedCount);
} else {
    assert.throws(function() {
        coll.bulkWrite([{
            updateOne: {
                filter: {str: "FOO"},
                update: {$set: {other: 99}},
                collation: {locale: "en_US", strength: 2}
            }
        }]);
    });
}

// updateMany with bulkWrite().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.bulkWrite([{
        updateMany: {
            filter: {str: "FOO"},
            update: {$set: {other: 99}},
            collation: {locale: "en_US", strength: 2}
        }
    }]);
    assert.eq(2, res.matchedCount);
} else {
    assert.throws(function() {
        coll.bulkWrite([{
            updateMany: {
                filter: {str: "FOO"},
                update: {$set: {other: 99}},
                collation: {locale: "en_US", strength: 2}
            }
        }]);
    });
}

// replaceOne with bulkWrite().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.bulkWrite([{
        replaceOne: {
            filter: {str: "FOO"},
            replacement: {str: "bar"},
            collation: {locale: "en_US", strength: 2}
        }
    }]);
    assert.eq(1, res.matchedCount);
} else {
    assert.throws(function() {
        coll.bulkWrite([{
            replaceOne: {
                filter: {str: "FOO"},
                replacement: {str: "bar"},
                collation: {locale: "en_US", strength: 2}
            }
        }]);
    });
}

// deleteOne with bulkWrite().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.bulkWrite(
        [{deleteOne: {filter: {str: "FOO"}, collation: {locale: "en_US", strength: 2}}}]);
    assert.eq(1, res.deletedCount);
} else {
    assert.throws(function() {
        coll.bulkWrite(
            [{deleteOne: {filter: {str: "FOO"}, collation: {locale: "en_US", strength: 2}}}]);
    });
}

// deleteMany with bulkWrite().
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "foo"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.bulkWrite(
        [{deleteMany: {filter: {str: "FOO"}, collation: {locale: "en_US", strength: 2}}}]);
    assert.eq(2, res.deletedCount);
} else {
    assert.throws(function() {
        coll.bulkWrite(
            [{deleteMany: {filter: {str: "FOO"}, collation: {locale: "en_US", strength: 2}}}]);
    });
}

// Two deleteOne ops with bulkWrite using different collations.
coll.drop();
assert.commandWorked(coll.insert({_id: 1, str: "foo"}));
assert.commandWorked(coll.insert({_id: 2, str: "bar"}));
if (db.getMongo().writeMode() === "commands") {
    var res = coll.bulkWrite([
        {deleteOne: {filter: {str: "FOO"}, collation: {locale: "fr", strength: 2}}},
        {deleteOne: {filter: {str: "BAR"}, collation: {locale: "en_US", strength: 2}}}
    ]);
    assert.eq(2, res.deletedCount);
} else {
    assert.throws(function() {
        coll.bulkWrite([
            {deleteOne: {filter: {str: "FOO"}, collation: {locale: "fr", strength: 2}}},
            {deleteOne: {filter: {str: "BAR"}, collation: {locale: "en_US", strength: 2}}}
        ]);
    });
}

// applyOps.
if (!isMongos) {
    coll.drop();
    assert.commandWorked(
        db.createCollection("collation", {collation: {locale: "en_US", strength: 2}}));
    assert.commandWorked(coll.insert({_id: "foo", x: 5, str: "bar"}));

    // preCondition.q respects collection default collation.
    assert.commandFailed(db.runCommand({
        applyOps: [{op: "u", ns: coll.getFullName(), o2: {_id: "foo"}, o: {$set: {x: 6}}}],
        preCondition: [{ns: coll.getFullName(), q: {_id: "not foo"}, res: {str: "bar"}}]
    }));
    assert.eq(5, coll.findOne({_id: "foo"}).x);
    assert.commandWorked(db.runCommand({
        applyOps: [{op: "u", ns: coll.getFullName(), o2: {_id: "foo"}, o: {$set: {x: 6}}}],
        preCondition: [{ns: coll.getFullName(), q: {_id: "FOO"}, res: {str: "bar"}}]
    }));
    assert.eq(6, coll.findOne({_id: "foo"}).x);

    // preCondition.res respects collection default collation.
    assert.commandFailed(db.runCommand({
        applyOps: [{op: "u", ns: coll.getFullName(), o2: {_id: "foo"}, o: {$set: {x: 7}}}],
        preCondition: [{ns: coll.getFullName(), q: {_id: "foo"}, res: {str: "not bar"}}]
    }));
    assert.eq(6, coll.findOne({_id: "foo"}).x);
    assert.commandWorked(db.runCommand({
        applyOps: [{op: "u", ns: coll.getFullName(), o2: {_id: "foo"}, o: {$set: {x: 7}}}],
        preCondition: [{ns: coll.getFullName(), q: {_id: "foo"}, res: {str: "BAR"}}]
    }));
    assert.eq(7, coll.findOne({_id: "foo"}).x);

    // <operation>.o2 respects collection default collation.
    assert.commandWorked(db.runCommand(
        {applyOps: [{op: "u", ns: coll.getFullName(), o2: {_id: "FOO"}, o: {$set: {x: 8}}}]}));
    assert.eq(8, coll.findOne({_id: "foo"}).x);
}

// Test that the collection created with the "cloneCollectionAsCapped" command inherits the
// default collation of the corresponding collection. We skip running this command in a sharded
// cluster because it isn't supported by mongos.
if (!isMongos) {
    const clonedColl = db.collation_cloned;

    coll.drop();
    clonedColl.drop();

    // Create a collection with a non-simple default collation.
    assert.commandWorked(
        db.runCommand({create: coll.getName(), collation: {locale: "en", strength: 2}}));
    const originalCollectionInfos = db.getCollectionInfos({name: coll.getName()});
    assert.eq(originalCollectionInfos.length, 1, tojson(originalCollectionInfos));

    assert.commandWorked(coll.insert({_id: "FOO"}));
    assert.commandWorked(coll.insert({_id: "bar"}));
    assert.eq([{_id: "FOO"}],
              coll.find({_id: "foo"}).toArray(),
              "query should have performed a case-insensitive match");

    var cloneCollOutput = db.runCommand(
        {cloneCollectionAsCapped: coll.getName(), toCollection: clonedColl.getName(), size: 4096});
    assert.commandWorked(cloneCollOutput);
    const clonedCollectionInfos = db.getCollectionInfos({name: clonedColl.getName()});
    assert.eq(clonedCollectionInfos.length, 1, tojson(clonedCollectionInfos));
    assert.eq(originalCollectionInfos[0].options.collation,
              clonedCollectionInfos[0].options.collation);
    assert.eq([{_id: "FOO"}], clonedColl.find({_id: "foo"}).toArray());
}

// Test that the find command's min/max options respect the collation.
if (db.getMongo().useReadCommands()) {
    coll.drop();
    assert.commandWorked(coll.insert({str: "a"}));
    assert.commandWorked(coll.insert({str: "A"}));
    assert.commandWorked(coll.insert({str: "b"}));
    assert.commandWorked(coll.insert({str: "B"}));
    assert.commandWorked(coll.insert({str: "c"}));
    assert.commandWorked(coll.insert({str: "C"}));
    assert.commandWorked(coll.insert({str: "d"}));
    assert.commandWorked(coll.insert({str: "D"}));

    // This query should fail, since there is no index to support the min/max.
    let err = assert.throws(() => coll.find()
                                      .min({str: "b"})
                                      .max({str: "D"})
                                      .collation({locale: "en_US", strength: 2})
                                      .itcount());
    assert.commandFailedWithCode(err, 51173);

    // Even after building an index with the right key pattern, the query should fail since the
    // collations don't match.
    assert.commandWorked(coll.createIndex({str: 1}, {name: "noCollation"}));
    err = assert.throws(() => coll.find()
                                  .min({str: "b"})
                                  .max({str: "D"})
                                  .collation({locale: "en_US", strength: 2})
                                  .hint({str: 1})
                                  .itcount());
    assert.commandFailedWithCode(err, 51174);

    // This query should fail, because the hinted index does not match the requested
    // collation, and the 'max' value is a string, which means we cannot ignore the
    // collation.
    const caseInsensitive = {locale: "en", strength: 2};
    assert.commandWorked(coll.dropIndexes());
    assert.commandWorked(coll.createIndex({str: 1}));
    err = assert.throws(() => coll.find({}, {_id: 0})
                                  .min({str: MinKey})
                                  .max({str: "Hello1"})
                                  .hint({str: 1})
                                  .collation(caseInsensitive)
                                  .toArray());
    assert.commandFailedWithCode(err, 51174);

    // After building an index with the case-insensitive US English collation, the query should
    // work. Furthermore, the bounds defined by the min and max should respect the
    // case-insensitive collation.
    assert.commandWorked(coll.createIndex(
        {str: 1}, {name: "withCollation", collation: {locale: "en_US", strength: 2}}));
    assert.eq(4,
              coll.find()
                  .min({str: "b"})
                  .max({str: "D"})
                  .collation({locale: "en_US", strength: 2})
                  .hint("withCollation")
                  .itcount());

    // Ensure results from index with min/max query are sorted to match requested collation.
    coll.drop();
    assert.commandWorked(coll.ensureIndex({a: 1, b: 1}));
    assert.commandWorked(
        coll.insert([{a: 1, b: 1}, {a: 1, b: 2}, {a: 1, b: "A"}, {a: 1, b: "a"}, {a: 2, b: 2}]));
    var expected = [{a: 1, b: 1}, {a: 1, b: 2}, {a: 1, b: "a"}, {a: 1, b: "A"}, {a: 2, b: 2}];
    res = coll.find({}, {_id: 0})
              .hint({a: 1, b: 1})
              .min({a: 1, b: 1})
              .max({a: 2, b: 3})
              .collation({locale: "en_US", strength: 3})
              .sort({a: 1, b: 1});
    assert.eq(res.toArray(), expected);
    res = coll.find({}, {_id: 0})
              .hint({a: 1, b: 1})
              .min({a: 1, b: 1})
              .collation({locale: "en_US", strength: 3})
              .sort({a: 1, b: 1});
    assert.eq(res.toArray(), expected);
    res = coll.find({}, {_id: 0})
              .hint({a: 1, b: 1})
              .max({a: 2, b: 3})
              .collation({locale: "en_US", strength: 3})
              .sort({a: 1, b: 1});
    assert.eq(res.toArray(), expected);

    // A min/max query that can use an index whose collation doesn't match should require a sort
    // stage if there are any in-bounds strings. Verify this using explain.
    explainRes = coll.find({}, {_id: 0})
                     .hint({a: 1, b: 1})
                     .max({a: 2, b: 3})
                     .collation({locale: "en_US", strength: 3})
                     .sort({a: 1, b: 1})
                     .explain();
    assert.commandWorked(explainRes);
    assert(planHasStage(db, explainRes.queryPlanner.winningPlan, "SORT"));

    // This query should fail since min has a string as one of it's boundaries, and the
    // collation doesn't match that of the index.
    assert.throws(() => coll.find({}, {_id: 0})
                            .hint({a: 1, b: 1})
                            .min({a: 1, b: "A"})
                            .max({a: 2, b: 1})
                            .collation({locale: "en_US", strength: 3})
                            .sort({a: 1, b: 1})
                            .itcount());
}
})();