TEST_F(CollectionCatalogTimestampTest, IndexCatalogEntryCopying) {
    const NamespaceString nss("test.abc");
    createCollection(opCtx.get(), nss, Timestamp::min());
    IndexCatalogEntry* entry;
    {
        // Start but do not finish an index build.
        IndexSpec spec;
        spec.version(1).name("x_1").addKeys(BSON("x" << 1));
        auto desc = std::make_unique<IndexDescriptor>(IndexNames::BTREE, spec.toBSON());
        AutoGetCollection autoColl(opCtx.get(), nss, MODE_X);
        WriteUnitOfWork wuow(opCtx.get());
        auto collWriter = autoColl.getWritableCollection(opCtx.get());
        ASSERT_OK(collWriter->prepareForIndexBuild(opCtx.get(), desc.get(), boost::none, false));
        entry = collWriter->getIndexCatalog()->createIndexEntry(
            opCtx.get(), collWriter, std::move(desc), CreateIndexEntryFlags::kNone);
        wuow.commit();
    }
    // In a different client, open the latest collection instance of 'nss'
    auto newClient = opCtx->getServiceContext()->makeClient("alternativeClient");
    auto newOpCtx = newClient->makeOperationContext();
    auto latestCatalog = CollectionCatalog::latest(newOpCtx.get());
    auto latestColl =
        latestCatalog->establishConsistentCollection(newOpCtx.get(), nss, boost::none);
    ASSERT_EQ(1, latestColl->getIndexCatalog()->numIndexesTotal());
    ASSERT_EQ(0, latestColl->getIndexCatalog()->numIndexesReady());
    ASSERT_EQ(1, latestColl->getIndexCatalog()->numIndexesInProgress());
    // The index is NOT ready.
    auto descLatestBefore = latestColl->getIndexCatalog()->findIndexByName(
        newOpCtx.get(),
        "x_1",
        IndexCatalog::InclusionPolicy::kReady | IndexCatalog::InclusionPolicy::kFrozen |
            IndexCatalog::InclusionPolicy::kUnfinished);
    auto entryLatestBefore = latestColl->getIndexCatalog()->getEntry(descLatestBefore);
    ASSERT(!entryLatestBefore->isReady());
    {
        // Now finish the index build on the original OperationContext.
        AutoGetCollection autoColl(opCtx.get(), nss, MODE_X);
        WriteUnitOfWork wuow(opCtx.get());
        auto collWriter = autoColl.getWritableCollection(opCtx.get());
        collWriter->getIndexCatalog()->indexBuildSuccess(opCtx.get(), collWriter, entry);
        wuow.commit();
    }
    // Container counts are still correct.
    ASSERT_EQ(1, latestColl->getIndexCatalog()->numIndexesTotal());
    ASSERT_EQ(0, latestColl->getIndexCatalog()->numIndexesReady());
    ASSERT_EQ(1, latestColl->getIndexCatalog()->numIndexesInProgress());
    // But the index is marked as ready now. When the collection clone happened above, it made a
    // copy of the containers, which is std::vector<std::shared_ptr<IndexCatalogEntry>> so we only
    // upped the ref count.
    auto descLatestAfter = latestColl->getIndexCatalog()->findIndexByName(
        newOpCtx.get(),
        "x_1",
        IndexCatalog::InclusionPolicy::kReady | IndexCatalog::InclusionPolicy::kFrozen |
            IndexCatalog::InclusionPolicy::kUnfinished);
    auto entryLatestAfter = latestColl->getIndexCatalog()->getEntry(descLatestAfter);
    ASSERT(!entryLatestAfter->isReady());
}