Bug 1486445 - P2 - Add a wpt test to verify url of a service worker redirected request is propagated to response; r=asuth

This patch add a wpt test to ensure the service worker redirected request URL
is propagated to the outer response.

Differential Revision: https://phabricator.services.mozilla.com/D4763

--HG--
extra : moz-landing-system : lando

testing/web-platform/tests/service-workers/service-worker/redirected-response.https.html

@@ -33,6 +33,11 @@ function redirected_test(options) {
         assert_equals(
             cloned_response.redirected, options.expected_redirected,
             'The redirected flag of cloned response must match. URL: ' + options.url);
+        if (options.expected_response_url) {
+            assert_equals(
+                cloned_response.url, options.expected_response_url,
+                'The URL does not meet expectation. URL: ' + options.url);
+        }
         return cache.put(options.url, response);
       })
     .then(_ => cache.match(options.url))
@@ -348,4 +353,23 @@ promise_test(t => setup_and_clean()
         });
     }),
   'Fetch should not follow the redirect response 21 times.');
+
+// =======================================================
+// A test for verifying the url of a service-worker-redirected request is
+// propagated to the outer response.
+// =======================================================
+promise_test(t => setup_and_clean()
+    .then(() => {
+      const url = host_info['HTTPS_ORIGIN'] + base_path() + 'dummy?url=' +
+                  encodeURIComponent(TARGET_URL) +'&sw=fetch-url';
+      return redirected_test({url: url,
+                              fetch_option: {},
+                              fetch_method: frame.contentWindow.fetch,
+                              expected_type: 'basic',
+                              expected_redirected: false,
+                              expected_intercepted_urls: [url],
+                              expected_response_url: TARGET_URL});
+    }),
+  'The URL for the service worker redirected request should be propagated to ' +
+  'response.');
 </script>

testing/web-platform/tests/service-workers/service-worker/resources/redirect-worker.js

@@ -68,6 +68,8 @@ self.addEventListener('fetch', function(event) {
         return Response.redirect(params['url']);
       } else if (params['sw'] == 'fetch') {
         return fetch(event.request);
+      } else if (params['sw'] == 'fetch-url') {
+        return fetch(params['url']);
       } else if (params['sw'] == 'follow') {
         return fetch(new Request(event.request.url, {redirect: 'follow'}));
       } else if (params['sw'] == 'manual') {