1 files changed, 48 insertions, 0 deletions
diff --git a/testing/web-platform/tests/html/semantics/document-metadata/the-style-element/mutations.window.js b/testing/web-platform/tests/html/semantics/document-metadata/the-style-element/mutations.window.js
new file mode 100644
index 0000000000..1c93b40394
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/document-metadata/the-style-element/mutations.window.js
@@ -0,0 +1,48 @@
+test(t => {
+  const style = document.body.appendChild(document.createElement("style"));
+  const sheet = style.sheet;
+  t.add_cleanup(() => style.remove());
+  assert_not_equals(sheet, null);
+  style.appendChild(new Comment());
+  assert_not_equals(sheet, style.sheet);
+}, "Mutating the style element: inserting a Comment node");
+
+test(t => {
+  const style = document.body.appendChild(document.createElement("style"));
+  t.add_cleanup(() => style.remove());
+  const comment = style.appendChild(new Comment());
+  const sheet = style.sheet;
+  comment.appendData("x");
+  assert_not_equals(sheet, style.sheet);
+}, "Mutating the style element: mutating a Comment node");
+
+test(t => {
+  const style = document.body.appendChild(document.createElement("style"));
+  t.add_cleanup(() => style.remove());
+  const text1 = style.appendChild(new Text("1"));
+  const text2 = style.appendChild(new Text("2"));
+  assert_equals(style.textContent, "12");
+  assert_equals(style.childNodes.length, 2);
+  const sheet = style.sheet;
+  style.normalize();
+  assert_equals(style.childNodes.length, 1);
+  assert_not_equals(sheet, style.sheet);
+}, "Mutating the style element: using normalize()");
+
+test(t => {
+  const style = document.body.appendChild(document.createElement("style"));
+  t.add_cleanup(() => style.remove());
+  const comment = style.appendChild(new Comment());
+  const sheet = style.sheet;
+  comment.remove();
+  assert_not_equals(sheet, style.sheet);
+}, "Mutating the style element: removing a Comment node");
+
+test(t => {
+  const style = document.body.appendChild(document.createElement("style"));
+  const sheet = style.sheet;
+  t.add_cleanup(() => style.remove());
+  assert_not_equals(sheet, null);
+  style.appendChild(new DocumentFragment());
+  assert_equals(sheet, style.sheet);
+}, "Mutating the style element: inserting an empty DocumentFragment node");