Kderusso/sparse vector ci failure (#117930) (#118014)

* Fix CI failure in SparseVectorQueryBuilderTests

Author: kderusso

muted-tests.yml

@@ -411,6 +411,3 @@ tests:
   issue: https://github.com/elastic/elasticsearch/issues/117805
 - class: org.elasticsearch.xpack.security.authc.ldap.UserAttributeGroupsResolverTests
   issue: https://github.com/elastic/elasticsearch/issues/116537
-- class: org.elasticsearch.xpack.core.ml.search.SparseVectorQueryBuilderTests
-  method: testToQuery
-  issue: https://github.com/elastic/elasticsearch/issues/117998

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/search/SparseVectorQueryBuilderTests.java

@@ -232,6 +232,12 @@ public void testToQuery() throws IOException {
 
     private void testDoToQuery(SparseVectorQueryBuilder queryBuilder, SearchExecutionContext context) throws IOException {
         Query query = queryBuilder.doToQuery(context);
+
+        // test query builder can randomly have no vectors, which rewrites to a MatchNoneQuery - nothing more to do in this case.
+        if (query instanceof MatchNoDocsQuery) {
+            return;
+        }
+
         assertTrue(query instanceof SparseVectorQueryWrapper);
         var sparseQuery = (SparseVectorQueryWrapper) query;
         if (queryBuilder.shouldPruneTokens()) {