(solr) 09/15: Test fix: TestCollapseQParserPlugin

[ds...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

dsmiley pushed a commit to branch branch_9x
in repository https://gitbox.apache.org/repos/asf/solr.git

commit 988d8b13c38dc929c409efee76ce82e0cdfb7ef4
Author: David Smiley <ds...@apache.org>
AuthorDate: Wed Oct 7 15:32:17 2026 -0400

    Test fix: TestCollapseQParserPlugin
    
    Flaky due to docid re-order.
    
    (cherry picked from commit f0ec950113bce6430d3c08032697e6dde20701df)
    (cherry picked from commit 9cace892d092410b7ffa3cda7fd0bdb9f2babe50)
---
 .../src/test/org/apache/solr/search/TestCollapseQParserPlugin.java     | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/solr/core/src/test/org/apache/solr/search/TestCollapseQParserPlugin.java b/solr/core/src/test/org/apache/solr/search/TestCollapseQParserPlugin.java
index 7c193f87a73..964010d7dd1 100644
--- a/solr/core/src/test/org/apache/solr/search/TestCollapseQParserPlugin.java
+++ b/solr/core/src/test/org/apache/solr/search/TestCollapseQParserPlugin.java
@@ -32,6 +32,7 @@ import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SolrInputDocument;
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.params.SolrParams;
+import org.apache.solr.index.LogDocMergePolicyFactory;
 import org.apache.solr.search.CollapsingQParserPlugin.GroupHeadSelector;
 import org.apache.solr.search.CollapsingQParserPlugin.GroupHeadSelectorType;
 import org.junit.Before;
@@ -44,6 +45,8 @@ public class TestCollapseQParserPlugin extends SolrTestCaseJ4 {
     // we need DVs on point fields to compute stats & facets
     if (Boolean.getBoolean(NUMERIC_POINTS_SYSPROP))
       System.setProperty(NUMERIC_DOCVALUES_SYSPROP, "true");
+    // tie-breaking on group head depends on docid order; avoid merges that reorder docs
+    systemSetPropertySolrTestsMergePolicyFactory(LogDocMergePolicyFactory.class.getName());
     initCore("solrconfig-collapseqparser.xml", "schema11.xml");
   }