SERVER-48066 Don't allow update shard key concurrency test to update shard key to same value

(cherry picked from commit dc30d9e9d387a946bcabda92007c60a8fce88337)

1 files changed, 9 insertions, 6 deletions

diff --git a/jstests/concurrency/fsm_workloads/random_moveChunk_update_shard_key.js b/jstests/concurrency/fsm_workloads/random_moveChunk_update_shard_key.js
index c034b8d06dc..cf5a430f366 100644
--- a/jstests/concurrency/fsm_workloads/random_moveChunk_update_shard_key.js
+++ b/jstests/concurrency/fsm_workloads/random_moveChunk_update_shard_key.js
@@ -114,12 +114,15 @@ var $config = extendWorkload($config, function($config, $super) {
         const partitionSizeHalf = Math.floor(this.partitionSize / 2);
         const partitionMedian = partitionSizeHalf + this.partition.lower;
 
-        // If moveAcrossChunks is true, move the randomly generated shardKey to the other
-        // half of the partition, which will be on the other chunk owned by this thread.
-        let newShardKey = this.partition.lower + Math.floor(Math.random() * partitionSizeHalf);
-
-        if (moveAcrossChunks || currentShardKey >= partitionMedian) {
-            newShardKey += partitionSizeHalf;
+        let newShardKey = currentShardKey;
+        while (newShardKey == currentShardKey) {
+            // If moveAcrossChunks is true, move the randomly generated shardKey to the other
+            // half of the partition, which will be on the other chunk owned by this thread.
+            newShardKey = this.partition.lower + Math.floor(Math.random() * partitionSizeHalf);
+
+            if (moveAcrossChunks || currentShardKey >= partitionMedian) {
+                newShardKey += partitionSizeHalf;
+            }
         }
 
         return {