From db65956ab2311d7c93af8df59626382fba209d28 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Zugmeyer?= <benoit.zugmeyer@datadoghq.com>
Date: Mon, 11 Dec 2023 18:37:16 +0100
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20[RUM-2280]=20fix=20duplicated=20?=
 =?UTF-8?q?mutations=20when=20using=20Shadow=20DOM?=
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---
 packages/rum/src/domain/record/record.spec.ts    | 16 ++++++++++++++++
 .../src/domain/record/shadowRootsController.ts   |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/packages/rum/src/domain/record/record.spec.ts b/packages/rum/src/domain/record/record.spec.ts
index f94f007b1b..9a27282c12 100644
--- a/packages/rum/src/domain/record/record.spec.ts
+++ b/packages/rum/src/domain/record/record.spec.ts
@@ -311,6 +311,22 @@ describe('record', () => {
       expect(innerMutationData.isChecked).toBe(true)
     })
 
+    it('should record the change event inside a shadow root only once, regardless if the DOM is serialized multiple times', () => {
+      const radio = appendElement('<input type="radio"/>', createShadow()) as HTMLInputElement
+      startRecording()
+
+      recordApi.takeSubsequentFullSnapshot()
+
+      radio.checked = true
+      radio.dispatchEvent(createNewEvent('change', { target: radio, composed: false }))
+
+      const inputRecords = getEmittedRecords().filter(
+        (record) => record.type === RecordType.IncrementalSnapshot && record.data.source === IncrementalSource.Input
+      )
+
+      expect(inputRecords.length).toBe(1)
+    })
+
     it('should clean the state once the shadow dom is removed to avoid memory leak', () => {
       const shadowRoot = createShadow()
       appendElement('<div class="toto"></div>', shadowRoot)
diff --git a/packages/rum/src/domain/record/shadowRootsController.ts b/packages/rum/src/domain/record/shadowRootsController.ts
index db2a5c98c3..11bb2e346b 100644
--- a/packages/rum/src/domain/record/shadowRootsController.ts
+++ b/packages/rum/src/domain/record/shadowRootsController.ts
@@ -30,6 +30,9 @@ export const initShadowRootsController = (
 
   const shadowRootsController: ShadowRootsController = {
     addShadowRoot: (shadowRoot: ShadowRoot) => {
+      if (controllerByShadowRoot.has(shadowRoot)) {
+        return
+      }
       const { stop: stopMutationObserver, flush } = initMutationObserver(
         mutationCb,
         configuration,