3 files changed, 50 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/fetching/support/echo-css.py b/testing/web-platform/tests/css/fetching/support/echo-css.py
new file mode 100644
index 0000000000..bbfd3f07c0
--- /dev/null
+++ b/testing/web-platform/tests/css/fetching/support/echo-css.py
@@ -0,0 +1,7 @@
+import sys
+import json
+
+def main(request, response):
+    content = request.GET.first(b"content", None)
+    response.headers.set(b"Content-Type", "text/css");
+    return content
diff --git a/testing/web-platform/tests/css/fetching/support/echo-headers.py b/testing/web-platform/tests/css/fetching/support/echo-headers.py
new file mode 100644
index 0000000000..9feb6f91a4
--- /dev/null
+++ b/testing/web-platform/tests/css/fetching/support/echo-headers.py
@@ -0,0 +1,24 @@
+import sys
+import json
+
+def main(request, response):
+    token = request.GET.first(b"token", None)
+    location = request.GET.first(b"location", None)
+    store = request.server.stash.take(token)
+    headers = {}
+    if (location == b"echo"):
+        return store
+
+    if (store == None):
+        store = {}
+    else:
+        store = json.loads(store)
+
+    for header in request.headers:
+        headers[header.decode('utf-8')] = request.headers.get(header).decode('utf-8')
+
+    store[location.decode('utf-8')] = headers
+
+    request.server.stash.put(token, json.dumps(store))
+    response.status = 302
+    response.headers.set(b"Location", location)
diff --git a/testing/web-platform/tests/css/fetching/support/echo-helper.js b/testing/web-platform/tests/css/fetching/support/echo-helper.js
new file mode 100644
index 0000000000..15bec65033
--- /dev/null
+++ b/testing/web-platform/tests/css/fetching/support/echo-helper.js
@@ -0,0 +1,19 @@
+function get_resource_echo_url(uid, url) {
+    return `/css/fetching/support/echo-headers.py?token=${uid}&location=${url}`
+}
+
+function wait_for_resource(url) {
+    return new Promise(resolve => {
+        const po = new PerformanceObserver(list => {
+            const entries = list.getEntries();
+            if (entries.find(e => e.name.includes(url)))
+                resolve();
+        })
+        po.observe({type: "resource", buffered: true});
+    });
+}
+
+async function get_headers(uid) {
+    return await (await fetch(`/css/fetching/support/echo-headers.py?token=${uid}&location=echo`)).json()
+}
+