SERVER-36119 Explicitly downgrade new shard's FCV in the mixed version convert_to_and_from_sharded.js

1 files changed, 14 insertions, 2 deletions

diff --git a/jstests/sharding/convert_to_and_from_sharded.js b/jstests/sharding/convert_to_and_from_sharded.js
index 08024a64104..f6f9abaed2f 100644
--- a/jstests/sharding/convert_to_and_from_sharded.js
+++ b/jstests/sharding/convert_to_and_from_sharded.js
@@ -4,9 +4,10 @@
  * @tags: [requires_persistence]
  */
 (function() {
-
     "use strict";
 
+    load("jstests/libs/feature_compatibility_version.js");
+
     var NUM_NODES = 3;
 
     /**
@@ -35,6 +36,18 @@
 
     var priConn = replShard.getPrimary();
 
+    // Initialized replica sets with data on them will report themselves as the latest FCV of the
+    // binary that they are running. This poses a problem when this test is run in the mixed version
+    // suite because mongos will be 'last-stable', but if this node is started with the latest
+    // binaries, it will report itself as the 'latest' FCV, which would cause mongos to refuse to
+    // connect to it and shutdown.
+    //
+    // In order to work around this, in the mixed version suite, be pessimistic and always set this
+    // node to the 'last-stable' FCV
+    if (jsTestOptions().shardMixedBinVersions) {
+        assert.commandWorked(priConn.adminCommand({setFeatureCompatibilityVersion: lastStableFCV}));
+    }
+
     assert.writeOK(priConn.getDB('test').unsharded.insert({_id: 'marker'}));
     checkBasicCRUD(priConn.getDB('test').unsharded);
 
@@ -112,5 +125,4 @@
     checkBasicCRUD(priConn.getDB('test').sharded);
 
     replShard.stopSet();
-
 })();