From bcb55003c81e15cc4c2cb556ad5077b4316c6c40 Mon Sep 17 00:00:00 2001
From: Jordi Serra Torrens <jordi.serra-torrens@mongodb.com>
Date: Fri, 29 Dec 2023 12:20:33 +0000
Subject: [PATCH] Repro BF-31267

---
 jstests/sharding/repro-bf-31267.js | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 jstests/sharding/repro-bf-31267.js

diff --git a/jstests/sharding/repro-bf-31267.js b/jstests/sharding/repro-bf-31267.js
new file mode 100644
index 00000000000..bb72d21d198
--- /dev/null
+++ b/jstests/sharding/repro-bf-31267.js
@@ -0,0 +1,29 @@
+/**
+ * Repro BF-31267
+ */
+
+// Cluster starts with FCV 7.3.
+var st = new ShardingTest({shards: 1});
+let configSettingsColl = st.s.getDB('config')['settings'];
+
+// Assert that schema validation is enforced.
+assert.commandFailed(
+    configSettingsColl.update({_id: 'balancer'}, {$set: {stopped: 'bad'}}, {upsert: true}));
+
+// Downgrade to FCV 7.0.
+assert.commandWorked(st.s.adminCommand({setFeatureCompatibilityVersion: '7.0', confirm: true}));
+
+// Assert that schema validation is no longer enforced.
+assert.commandWorked(
+    configSettingsColl.update({_id: 'balancer'}, {$set: {stopped: 'bad'}}, {upsert: true}));
+assert.commandWorked(configSettingsColl.update({_id: 'balancer'}, {$unset: {stopped: 'bad'}}));
+
+// Upgrade back to FCV 7.3.
+assert.commandWorked(st.s.adminCommand({setFeatureCompatibilityVersion: '7.3', confirm: true}));
+
+// Assert that schema validation is enforced again. Repro: The test will fail here -- validation not
+// actually enforced.
+assert.commandFailed(
+    configSettingsColl.update({_id: 'balancer'}, {$set: {stopped: 'bad'}}, {upsert: true}));
+
+st.stop();
-- 
2.34.1