diff --git a/fetch/fetch-later/basic.tentative.https.window.js b/fetch/fetch-later/basic.tentative.https.window.js
index a8ca011a7c99287..55bdbc97127a9c0 100644
--- a/fetch/fetch-later/basic.tentative.https.window.js
+++ b/fetch/fetch-later/basic.tentative.https.window.js
@@ -7,7 +7,29 @@ test(() => {
   assert_throws_js(TypeError, () => fetchLater());
 }, `fetchLater() cannot be called without request.`);
 
+test(() => {
+  assert_throws_js(TypeError, () => fetchLater('http://www.google.com'));
+  assert_throws_js(TypeError, () => fetchLater('file://tmp'));
+  assert_throws_js(TypeError, () => fetchLater('ssh://example.com'));
+  assert_throws_js(TypeError, () => fetchLater('wss://example.com'));
+  assert_throws_js(TypeError, () => fetchLater('about:blank'));
+  assert_throws_js(TypeError, () => fetchLater(`javascript:alert('');`));
+}, `fetchLater() throws TypeError on non-HTTPS URL.`);
+
 test(() => {
   const result = fetchLater('/');
-  assert_false(result.sent);
+  assert_false(result.activated);
 }, `fetchLater()'s return tells the deferred request is not yet sent.`);
+
+test(() => {
+  const result = fetchLater('/');
+  assert_throws_js(TypeError, () => result.activated = true);
+}, `fetchLater() throws TypeError when mutating its returned state.`);
+
+test(() => {
+  const controller = new AbortController();
+  // Immediately aborts the controller.
+  controller.abort();
+  assert_throws_dom(
+      'AbortError', () => fetchLater('/', {signal: controller.signal}));
+}, `fetchLater() throws AbortError when its initial abort signal is aborted.`);
diff --git a/fetch/fetch-later/send-on-discard.tentative.https.window.js b/fetch/fetch-later/send-on-discard.tentative.https.window.js
new file mode 100644
index 000000000000000..4fde4e4ceb5da12
--- /dev/null
+++ b/fetch/fetch-later/send-on-discard.tentative.https.window.js
@@ -0,0 +1,46 @@
+// META: script=/resources/testharness.js
+// META: script=/resources/testharnessreport.js
+// META: script=/common/utils.js
+// META: script=/pending-beacon/resources/pending_beacon-helper.js
+
+'use strict';
+
+parallelPromiseTest(async t => {
+  const uuid = token();
+  const url = generateSetBeaconURL(uuid);
+  const numPerMethod = 20;
+  const total = numPerMethod * 2;
+
+  // Loads an iframe that creates `numPerMethod` GET & POST fetchLater requests.
+  const iframe = await loadScriptAsIframe(`
+    const url = "${url}";
+    for (let i = 0; i < ${numPerMethod}; i++) {
+      fetchLater(url);
+      fetchLater(url, {method: 'POST'});
+    }
+  `);
+  // Delete the iframe to trigger deferred request sending.
+  document.body.removeChild(iframe);
+
+  // The iframe should have sent all requests.
+  await expectBeacon(uuid, {count: total});
+}, 'A discarded document sends all its fetchLater requests.');
+
+parallelPromiseTest(async t => {
+  const uuid = token();
+  const url = generateSetBeaconURL(uuid);
+
+  // Loads an iframe that creates 2 fetchLater requests. One of them is aborted.
+  const iframe = await loadScriptAsIframe(`
+    const url = "${url}";
+    const controller = new AbortController();
+    fetchLater(url, {signal: controller.signal});
+    fetchLater(url, {method: 'POST'});
+    controller.abort();
+  `);
+  // Delete the iframe to trigger deferred request sending.
+  document.body.removeChild(iframe);
+
+  // The iframe should not send the aborted request.
+  await expectBeacon(uuid, {count: 1});
+}, 'A discarded document does not send an already aborted fetchLater request.');
diff --git a/fetch/fetch-later/sendondiscard.tentative.https.window.js b/fetch/fetch-later/sendondiscard.tentative.https.window.js
deleted file mode 100644
index 0613d18dffbfc98..000000000000000
--- a/fetch/fetch-later/sendondiscard.tentative.https.window.js
+++ /dev/null
@@ -1,28 +0,0 @@
-// META: script=/resources/testharness.js
-// META: script=/resources/testharnessreport.js
-// META: script=/common/utils.js
-// META: script=/pending-beacon/resources/pending_beacon-helper.js
-
-'use strict';
-
-parallelPromiseTest(async t => {
-  const uuid = token();
-  const url = generateSetBeaconURL(uuid);
-  const numPerMethod = 20;
-  const total = numPerMethod * 2;
-
-  // Loads an iframe that creates `numPerMethod` GET & POST fetchLater requests.
-  const iframe = await loadScriptAsIframe(`
-    const url = "${url}";
-    for (let i = 0; i < ${numPerMethod}; i++) {
-      let get = fetchLater(url);
-      let post = fetchLater(url, {method: 'POST'});
-    }
-  `);
-
-  // Delete the iframe to trigger deferred request sending.
-  document.body.removeChild(iframe);
-
-  // The iframe should have sent all requests.
-  await expectBeacon(uuid, {count: total});
-}, 'A discarded document sends all its fetchLater requests with default config.');