// This test asserts on query plans expected from unsharded collections.
// @tags: [
//   assumes_no_implicit_collection_creation_after_drop,
//   requires_fastcount,
// ]

// Test explain for {upsert: true} updates.

import {FixtureHelpers} from "jstests/libs/fixture_helpers.js";

let t = db.jstests_explain_upsert;
t.drop();

let explain;

// Explained upsert against an empty collection should succeed and be a no-op.
explain = db.runCommand({explain: {update: t.getName(), updates: [{q: {a: 1}, u: {a: 1}, upsert: true}]}});
if (FixtureHelpers.isMongos(db) || TestData.testingReplicaSetEndpoint) {
    assert.commandWorkedOrFailedWithCode(explain, ErrorCodes.NamespaceNotFound);
} else {
    // TODO(SERVER-18047): Make an explain against a non-existent database fail in an unsharded
    // environment.
    assert.commandWorked(explain);
}

// Collection should still not exist.
assert.eq(0, t.count());
assert(!db.getCollectionInfos({name: t.getName()}).length);

// Add a document to the collection.
t.insert({a: 3});

// An explained upsert against a non-empty collection should also succeed as a no-op.
explain = db.runCommand({explain: {update: t.getName(), updates: [{q: {a: 1}, u: {a: 1}, upsert: true}]}});
assert.commandWorked(explain);
assert.eq(1, t.count());
assert(db.getCollectionInfos({name: t.getName()}).length);