diff --git a/testing/web-platform/meta/MANIFEST.json b/testing/web-platform/meta/MANIFEST.json
index 879c47358212..b089f57a0eca 100644
--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -64843,6 +64843,16 @@
      {}
     ]
    ],
+   "service-workers/service-worker/resources/bytecheck-worker-imported-script.py": [
+    [
+     {}
+    ]
+   ],
+   "service-workers/service-worker/resources/bytecheck-worker.py": [
+    [
+     {}
+    ]
+   ],
    "service-workers/service-worker/resources/claim-with-redirect-iframe.html": [
     [
      {}
@@ -127676,6 +127686,12 @@
      {}
     ]
    ],
+   "service-workers/service-worker/update-bytecheck.https.html": [
+    [
+     "/service-workers/service-worker/update-bytecheck.https.html",
+     {}
+    ]
+   ],
    "service-workers/service-worker/update-recovery.https.html": [
     [
      "/service-workers/service-worker/update-recovery.https.html",
@@ -213561,6 +213577,14 @@
    "0ddb4f1cf84729ed673295719ec58a3e5d600a12",
    "support"
   ],
+  "service-workers/service-worker/resources/bytecheck-worker-imported-script.py": [
+   "772d029d4efbe22f62f3473d4afe9e501a792571",
+   "support"
+  ],
+  "service-workers/service-worker/resources/bytecheck-worker.py": [
+   "2693790af1dcd812bc3741db7fa355e23eef0e01",
+   "support"
+  ],
   "service-workers/service-worker/resources/claim-with-redirect-iframe.html": [
    "fdc472f4e9a591f0b471174b2aa1783107731f49",
    "support"
@@ -214353,6 +214377,10 @@
    "7c8c6c3edca83d54f1838eccf3afb0b1223c7a44",
    "testharness"
   ],
+  "service-workers/service-worker/update-bytecheck.https.html": [
+   "6562348b198124822297c6b622c3e63870427672",
+   "testharness"
+  ],
   "service-workers/service-worker/update-recovery.https.html": [
    "aac5705d6844e4a33200418504adb57053a45be2",
    "testharness"
diff --git a/testing/web-platform/tests/service-workers/service-worker/resources/bytecheck-worker-imported-script.py b/testing/web-platform/tests/service-workers/service-worker/resources/bytecheck-worker-imported-script.py
new file mode 100644
index 000000000000..e96022026c52
--- /dev/null
+++ b/testing/web-platform/tests/service-workers/service-worker/resources/bytecheck-worker-imported-script.py
@@ -0,0 +1,19 @@
+import time
+
+def main(request, response):
+    headers = [('Content-Type', 'application/javascript'),
+               ('Cache-Control', 'max-age=0')]
+
+    imported_content_type = ''
+    if 'imported' in request.GET:
+        imported_content_type = request.GET['imported']
+
+    imported_content = 'default'
+    if imported_content_type == 'time':
+        imported_content = time.time()
+
+    body = '''
+    // %s
+    ''' % (imported_content)
+
+    return headers, body
diff --git a/testing/web-platform/tests/service-workers/service-worker/resources/bytecheck-worker.py b/testing/web-platform/tests/service-workers/service-worker/resources/bytecheck-worker.py
new file mode 100644
index 000000000000..0b12de9f3084
--- /dev/null
+++ b/testing/web-platform/tests/service-workers/service-worker/resources/bytecheck-worker.py
@@ -0,0 +1,32 @@
+import time
+
+def main(request, response):
+    headers = [('Content-Type', 'application/javascript'),
+               ('Cache-Control', 'max-age=0')]
+
+    main_content_type = ''
+    if 'main' in request.GET:
+        main_content_type = request.GET['main']
+
+    main_content = 'default'
+    if main_content_type == 'time':
+        main_content = time.time()
+
+    imported_request_path = ''
+    if 'path' in request.GET:
+        imported_request_path = request.GET['path']
+
+    imported_request_type = ''
+    if 'imported' in request.GET:
+        imported_request_type = request.GET['imported']
+
+    imported_request = ''
+    if imported_request_type == 'time':
+        imported_request = '?imported=time';
+
+    body = '''
+    // %s
+    importScripts('%sbytecheck-worker-imported-script.py%s');
+    ''' % (main_content, imported_request_path, imported_request)
+
+    return headers, body
diff --git a/testing/web-platform/tests/service-workers/service-worker/update-bytecheck.https.html b/testing/web-platform/tests/service-workers/service-worker/update-bytecheck.https.html
new file mode 100644
index 000000000000..6e4c6ec403a9
--- /dev/null
+++ b/testing/web-platform/tests/service-workers/service-worker/update-bytecheck.https.html
@@ -0,0 +1,72 @@
+<!doctype html>
+<meta charset=utf-8>
+<title></title>
+<script src="/resources/testharness.js"></script>
+<script src="resources/testharness-helpers.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/test-helpers.sub.js"></script>
+<script>
+
+/*
+ * @param bolean cors
+ *   Determine wether the imported script should be a cross origin script.
+ * @param string main
+ *   Decide the content of the main script, where 'default' is for constant
+ *   content while 'time' is for time-variant content.
+ * @param string imported
+ *   Decide the content of the imported script, where 'default' is for constant
+ *   content while 'time' is for time-variant content.
+ */
+const settings = [{cors: false, main: 'default', imported: 'default'},
+                  {cors: false, main: 'default', imported: 'time'   },
+                  {cors: false, main: 'time',    imported: 'default'},
+                  {cors: false, main: 'time',    imported: 'time'   },
+                  {cors: true,  main: 'default', imported: 'default'},
+                  {cors: true,  main: 'default', imported: 'time'   },
+                  {cors: true,  main: 'time',    imported: 'default'},
+                  {cors: true,  main: 'time',    imported: 'time'   }];
+
+settings.reduce((p, s) => {
+  return p.then(promise_test(function(t) {
+    var path = !s.cors ? ''
+                       : 'https://www1.web-platform.test:8443/' +
+                         'service-workers/service-worker/resources/';
+    var script = 'resources/bytecheck-worker.py' +
+                 '?main=' + s.main +
+                 '&imported=' + s.imported +
+                 '&path=' + path;
+    var scope = 'resources/blank.html';
+
+    var swr, sw;
+    return Promise.resolve()
+      // Register a service worker.
+      .then(_ => service_worker_unregister_and_register(t, script, scope))
+      .then(r => swr = r)
+      .then(_ => wait_for_update(t, swr))
+      .then(w => sw = w)
+      .then(_ => wait_for_state(t, sw, 'activated'))
+      .then(_ => assert_array_equals([swr.active,
+                                      swr.waiting,
+                                      swr.installing],
+                                     [sw, null, null]))
+
+      // Update the service worker registration.
+      .then(_ => swr.update())
+      .then(_ => {
+         // If there should be a new service worker.
+         if (s.main === 'time' || s.imported === 'time') {
+           return wait_for_update(t, swr);
+         }
+         // Otherwise, make sure there is no newly created service worker.
+         assert_array_equals([swr.active,
+                              swr.waiting,
+                              swr.installing],
+                             [sw, null, null]);
+      })
+
+      // Unregister the service worker.
+      .then(_ => service_worker_unregister_and_done(t, scope));
+  }, `Test(cors: ${s.cors}, main: ${s.main}, imported: ${s.imported})`));
+}, Promise.resolve());
+
+</script>