* Rank fusion searchers are responsible for executing search queries and
 * can be combined to implement advanced ranking strategies.
 */
public abstract class RankFusionSearcher {
    /** The name of this searcher, lazily initialized. */
    protected String name;

    /**
     * Default constructor for creating a new rank fusion searcher instance.

     *
     * @return array of available RankFusionSearcher instances
     */
    protected RankFusionSearcher[] getAvailableSearchers() {
        if (searchers.isEmpty()) {
            logger.warn("No searchers registered");
            return new RankFusionSearcher[0];
        }
        if (availableSearcherNameSet.isEmpty()) {
            return searchers.toArray(new RankFusionSearcher[0]);
        }

        }
    }

    /**
     * Searcher that throws an exception during search.
     */
    static class ExceptionThrowingSearcher extends RankFusionSearcher {
        private final RuntimeException exception;

        ExceptionThrowingSearcher(RuntimeException exception) {
            this.exception = exception;
        }

        @Override

     */
    static class TestSearcher extends RankFusionSearcher {
        @Override
        protected SearchResult search(String query, SearchRequestParams params, OptionalThing<FessUserBean> userBean) {
            return SearchResult.create().build();
        }
    }

    /**
     * Custom searcher implementation.
     */
    static class CustomSearcher extends RankFusionSearcher {
        @Override

        processor.close();
    }

    /**
     * Test searcher that returns configurable number of documents.
     */
    static class TestSearcher extends RankFusionSearcher {
        private final long allRecordCount;

        TestSearcher(long allRecordCount) {
            this.allRecordCount = allRecordCount;
        }

        @Override

import org.opensearch.search.fetch.subphase.highlight.HighlightField;

/**
 * Default implementation of RankFusionSearcher that performs standard OpenSearch queries.
 * This searcher handles query execution, response processing, and document highlighting.
 */
public class DefaultSearcher extends RankFusionSearcher {

    /** Logger for this class. */
    private static final Logger logger = LogManager.getLogger(DefaultSearcher.class);

            }
        }
    }

    /**
     * Test searcher that returns configurable number of documents.
     */
    static class TestSearcher extends RankFusionSearcher {
        private final long allRecordCount;

        TestSearcher(long allRecordCount) {
            this.allRecordCount = allRecordCount;
        }

        @Override

                assertEquals(0, list.getStart());
            } else {
                fail();
            }
        }
    }

    static class TestMainSearcher extends RankFusionSearcher {

        private long allRecordCount;

        TestMainSearcher(int allRecordCount) {
            this.allRecordCount = allRecordCount;
        }

        @Override