// Call savePosition() on a reverse cursor without ever calling restorePosition().
    // May be useful to run this test under valgrind to verify there are no leaks.
    TEST( SortedDataInterface, SavePositionWithoutRestoreReversed ) {
        const std::unique_ptr<HarnessHelper> harnessHelper( newHarnessHelper() );
        const std::unique_ptr<SortedDataInterface> sorted( harnessHelper->newSortedDataInterface( false ) );

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            ASSERT( sorted->isEmpty( opCtx.get() ) );
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            {
                WriteUnitOfWork uow( opCtx.get() );
                ASSERT_OK( sorted->insert( opCtx.get(), key1, loc1, true ) );
                uow.commit();
            }
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            ASSERT_EQUALS( 1, sorted->numEntries( opCtx.get() ) );
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            const std::unique_ptr<SortedDataInterface::Cursor> cursor( sorted->newCursor(opCtx.get(), false) );
            cursor->savePositioned();
        }
    }
// Insert multiple keys and verify that fullValidate() either sets
// the `numKeysOut` as the number of entries in the index, or as -1.
TEST(SortedDataInterface, FullValidate) {
    const std::unique_ptr<HarnessHelper> harnessHelper(newHarnessHelper());
    const std::unique_ptr<SortedDataInterface> sorted(harnessHelper->newSortedDataInterface(false));

    {
        const std::unique_ptr<OperationContext> opCtx(harnessHelper->newOperationContext());
        ASSERT(sorted->isEmpty(opCtx.get()));
    }

    int nToInsert = 10;
    for (int i = 0; i < nToInsert; i++) {
        const std::unique_ptr<OperationContext> opCtx(harnessHelper->newOperationContext());
        {
            WriteUnitOfWork uow(opCtx.get());
            BSONObj key = BSON("" << i);
            RecordId loc(42, i * 2);
            ASSERT_OK(sorted->insert(opCtx.get(), key, loc, true));
            uow.commit();
        }
    }

    {
        const std::unique_ptr<OperationContext> opCtx(harnessHelper->newOperationContext());
        ASSERT_EQUALS(nToInsert, sorted->numEntries(opCtx.get()));
    }

    {
        long long numKeysOut;
        const std::unique_ptr<OperationContext> opCtx(harnessHelper->newOperationContext());
        sorted->fullValidate(opCtx.get(), &numKeysOut, NULL);
        // fullValidate() can set numKeysOut as the number of existing keys or -1.
        ASSERT(numKeysOut == nToInsert || numKeysOut == -1);
    }
}
    // Insert multiple keys and try to iterate through all of them
    // using a reverse cursor while calling savePosition() and
    // restorePosition() in succession.
    TEST( SortedDataInterface, SaveAndRestorePositionWhileIterateCursorReversed ) {
        const std::unique_ptr<HarnessHelper> harnessHelper( newHarnessHelper() );
        const std::unique_ptr<SortedDataInterface> sorted( harnessHelper->newSortedDataInterface( false ) );

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            ASSERT( sorted->isEmpty( opCtx.get() ) );
        }

        int nToInsert = 10;
        for ( int i = 0; i < nToInsert; i++ ) {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            {
                WriteUnitOfWork uow( opCtx.get() );
                BSONObj key = BSON( "" << i );
                RecordId loc( 42, i * 2 );
                ASSERT_OK( sorted->insert( opCtx.get(), key, loc, true ) );
                uow.commit();
            }
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            ASSERT_EQUALS( nToInsert, sorted->numEntries( opCtx.get() ) );
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            const std::unique_ptr<SortedDataInterface::Cursor> cursor( sorted->newCursor(opCtx.get(), false) );
            int i = nToInsert - 1;
            for (auto entry = cursor->seek(maxKey, true); entry; i--, entry = cursor->next()) {
                ASSERT_GTE(i, 0);
                ASSERT_EQ(entry, IndexKeyEntry(BSON( "" << i), RecordId(42, i * 2)));

                cursor->savePositioned();
                cursor->restore( opCtx.get() );
            }
            ASSERT( !cursor->next() );
            ASSERT_EQ(i, -1);
        }
    }
    // Insert the same key multiple times and try to iterate through each
    // occurrence using a forward cursor while calling savePosition() and
    // restorePosition() in succession. Verify that the RecordId is saved
    // as part of the current position of the cursor.
    TEST( SortedDataInterface, SaveAndRestorePositionWhileIterateCursorWithDupKeys ) {
        const std::unique_ptr<HarnessHelper> harnessHelper( newHarnessHelper() );
        const std::unique_ptr<SortedDataInterface> sorted( harnessHelper->newSortedDataInterface( false ) );

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            ASSERT( sorted->isEmpty( opCtx.get() ) );
        }

        int nToInsert = 10;
        for ( int i = 0; i < nToInsert; i++ ) {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            {
                WriteUnitOfWork uow( opCtx.get() );
                RecordId loc( 42, i * 2 );
                ASSERT_OK( sorted->insert( opCtx.get(), key1, loc, true /* allow duplicates */ ) );
                uow.commit();
            }
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            ASSERT_EQUALS( nToInsert, sorted->numEntries( opCtx.get() ) );
        }

        {
            const std::unique_ptr<OperationContext> opCtx( harnessHelper->newOperationContext() );
            const std::unique_ptr<SortedDataInterface::Cursor> cursor( sorted->newCursor(opCtx.get()) );
            int i = 0;
            for (auto entry = cursor->seek(minKey, true); entry; i++, entry = cursor->next()) {
                ASSERT_LT(i, nToInsert);
                ASSERT_EQ(entry, IndexKeyEntry(key1, RecordId(42, i * 2)));

                cursor->savePositioned();
                cursor->restore( opCtx.get() );
            }
            ASSERT( !cursor->next() );
            ASSERT_EQ(i, nToInsert);
        }
    }