An incomplete shard snapshot will prevent a shard from moving away from a node (see `SnapshotInProgressAllocationDecider`). That means that when a shard snapshot completes it may become possible to perform some shard movements that previously were not possible, so we should trigger a reroute to start those movements. AFAICT we do not trigger such a reroute today.
server/src/internalClusterTest/java/org/elasticsearch/snapshots/SnapshotsServiceIT.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.snapshots;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.elasticsearch.action.ActionFuture;
import org.elasticsearch.action.support.master.AcknowledgedResponse;
import org.elasticsearch.common.logging.Loggers;
import org.elasticsearch.snapshots.mockstore.MockRepository;
import org.elasticsearch.test.MockLogAppender;
import java.util.List;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.is;
public class SnapshotsServiceIT extends AbstractSnapshotIntegTestCase {