// Test that when an index drop rolls back, the index remains valid, and the server continues to
// correctly maintain the index's set of keys.
//
// This test was designed to reproduce SERVER-38372.
//
// @tags: [does_not_support_stepdowns, assumes_unsharded_collection]
(function() {
"use strict";

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

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

// Verify that the index has the expected set of keys.
assert.eq([{a: 1}, {a: 2}, {a: 3}], coll.find().hint({a: 1}).sort({a: 1}).returnKey().toArray());

// Run a dropIndexes command that attempts to drop both {a: 1} and an invalid index. This should
// cause the drop of {a: 1} to rollback, since the set of index drops happen atomically.
assert.commandFailedWithCode(
    db.runCommand({dropIndexes: coll.getName(), index: ["a_1", "unknown"]}),
    ErrorCodes.IndexNotFound);

// Verify that the {a: 1} index is still present in listIndexes output.
const indexList = coll.getIndexes();
assert.neq(undefined, indexList.find((idx) => idx.name === "a_1"), indexList);

// Write to the collection and ensure that the resulting set of index keys is correct.
assert.commandWorked(coll.update({a: 3}, {$inc: {a: 1}}));
assert.commandWorked(coll.insert({a: 5}));
assert.eq([{a: 1}, {a: 2}, {a: 4}, {a: 5}],
          coll.find().hint({a: 1}).sort({a: 1}).returnKey().toArray());
}());