From 737368039faaaebb76854299460983d75d9ebad0 Mon Sep 17 00:00:00 2001
From: Mason Freed <masonf@chromium.org>
Date: Fri, 26 Jan 2024 09:47:58 -0800
Subject: [PATCH] Add support for the shadow root clonable flag

This landed in the these two spec PRs:

  https://github.com/whatwg/dom/pull/892
  https://github.com/whatwg/dom/pull/1237

and was discussed here:

  https://github.com/whatwg/dom/issues/1137
  https://github.com/whatwg/dom/issues/1236

This CL adds support for clonable, behind a new ShadowRootClonable
flag. There was already a very basic test, but I added a few
more cases.

This should be fairly web compatible, but there is a risk since with
this feature enabled, declarative shadow roots in the main document
(as opposed to in a <template> element) will now be cloned. I will
launch this feature carefully. Safari has already shipped, and Gecko
has implemented this and plans to ship soon.

Fixed: 1510466
Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728
---
 shadow-dom/declarative/clonable.window.js | 10 -----
 shadow-dom/shadow-root-clonable.html      | 47 +++++++++++++++++++++++
 2 files changed, 47 insertions(+), 10 deletions(-)
 delete mode 100644 shadow-dom/declarative/clonable.window.js
 create mode 100644 shadow-dom/shadow-root-clonable.html
diff --git a/shadow-dom/declarative/clonable.window.js b/shadow-dom/declarative/clonable.window.js
deleted file mode 100644
index 5ebeacf37cbd8ab..000000000000000
--- a/shadow-dom/declarative/clonable.window.js
+++ /dev/null
@@ -1,10 +0,0 @@
-test(() => {
-  const div = document.createElement("div");
-  const root = div.attachShadow({ mode: "open", clonable: true });
-  root.appendChild(document.createElement("input"));
-  assert_true(root.clonable, "clonable attribute");
-
-  const cloned = div.cloneNode(true);
-  assert_equals(cloned.shadowRoot.children.length, 1, "children count");
-  assert_equals(cloned.shadowRoot.children[0].localName, "input", "children content");
-}, "attachShadow with clonable: true");
diff --git a/shadow-dom/shadow-root-clonable.html b/shadow-dom/shadow-root-clonable.html
new file mode 100644
index 000000000000000..1955ce4687d5f2e
--- /dev/null
+++ b/shadow-dom/shadow-root-clonable.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<title>Shadow root clonable flag</title>
+<link rel='author' href='mailto:krosylight@mozilla.com'>
+<link rel='author' href='mailto:masonf@chromium.org'>
+<link rel='help' href='https://dom.spec.whatwg.org/#shadowroot-clonable'>
+<script src='/resources/testharness.js'></script>
+<script src='/resources/testharnessreport.js'></script>
+
+<body>
+<script>
+test(() => {
+  const div = document.createElement("div");
+  const root = div.attachShadow({ mode: "open", clonable: true });
+  root.appendChild(document.createElement("input"));
+  assert_true(root.clonable, "clonable attribute");
+
+  const cloned = div.cloneNode(true);
+  assert_equals(cloned.shadowRoot.children.length, 1, "children count");
+  assert_equals(cloned.shadowRoot.children[0].localName, "input", "children content");
+}, "attachShadow with clonable: true");
+
+for (clonable of [false, undefined]) {
+  test(() => {
+    const div = document.createElement("div");
+    const root = div.attachShadow({ mode: "open", clonable });
+    root.appendChild(document.createElement("input"));
+    assert_false(root.clonable, "clonable attribute");
+
+    const cloned = div.cloneNode(true);
+    assert_true(!cloned.shadowRoot, "shadow should not be cloned");
+  }, `attachShadow with clonable: ${clonable}`);
+}
+
+test(() => {
+  const div = document.createElement("div");
+  div.setHTMLUnsafe('<div><template shadowrootmode=open><input></template></div>');
+  const root = div.firstElementChild.shadowRoot;
+  assert_true(!!root);
+  assert_true(root.clonable, "clonable is automatically true for declarative shadow root");
+
+  const cloned = div.cloneNode(true);
+  const clonedRoot = cloned.firstElementChild.shadowRoot;
+  assert_true(!!clonedRoot);
+  assert_equals(clonedRoot.children.length, 1, "children count");
+  assert_equals(clonedRoot.children[0].localName, "input", "children content");
+}, "declarative shadow roots get clonable: true automatically");
+</script>
