1 files changed, 8 insertions, 0 deletions
diff --git a/testing/web-platform/tests/fetch/api/response/response-headers-guard.any.js b/testing/web-platform/tests/fetch/api/response/response-headers-guard.any.js
new file mode 100644
index 0000000000..4a67d067a7
--- /dev/null
+++ b/testing/web-platform/tests/fetch/api/response/response-headers-guard.any.js
@@ -0,0 +1,8 @@
+// META: global=window,worker
+// META: title=Response: error static method
+
+promise_test (async () => {
+  const response = await fetch("../resources/data.json");
+  assert_throws_js(TypeError, () => { response.headers.append("name", "value"); });
+  assert_not_equals(response.headers.get("name"), "value", "response headers should be immutable");
+}, "Ensure response headers are immutable");