From e4145f987ba3006ce14cc29e497e4380a76e06f9 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Fri, 14 Jan 2022 22:27:42 -0500
Subject: [PATCH] test(document): repro #11172

---
 test/document.test.js | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/test/document.test.js b/test/document.test.js
index 23a62769098..d7ce27eeeec 100644
--- a/test/document.test.js
+++ b/test/document.test.js
@@ -7329,7 +7329,6 @@ describe('document', function() {
 
     const User = db.model('User', userSchema);
 
-
     const position = {
       geometry: {
         type: 'Point',
@@ -10960,6 +10959,29 @@ describe('document', function() {
     };
 
     await new Test(doc).save();
+  });
+
+  it('correctly handles modifying array subdoc after setting array subdoc to same value (gh-11172)', async function() {
+    const Order = db.model('Order', new Schema({
+      cumulativeConsumption: [{
+        _id: false,
+        unit: String,
+        value: Number
+      }]
+    }));
+
+    await Order.create({
+      cumulativeConsumption: [{ unit: 'foo', value: 123 }, { unit: 'bar', value: 42 }]
+    });
+
+    const doc = await Order.findOne();
+    doc.cumulativeConsumption = doc.toObject().cumulativeConsumption;
+
+    const match = doc.cumulativeConsumption.find(o => o.unit === 'bar');
+    match.value = 43;
+    match.unit = 'baz';
 
+    assert.ok(doc.isModified());
+    assert.ok(doc.isModified('cumulativeConsumption.1'));
   });
 });