1 files changed, 418 insertions, 0 deletions
diff --git a/testing/web-platform/tests/speculation-rules/prerender/resources/utils.js b/testing/web-platform/tests/speculation-rules/prerender/resources/utils.js
new file mode 100644
index 0000000000..f3a49f1deb
--- /dev/null
+++ b/testing/web-platform/tests/speculation-rules/prerender/resources/utils.js
@@ -0,0 +1,418 @@
+const STORE_URL = '/speculation-rules/prerender/resources/key-value-store.py';
+
+function assertSpeculationRulesIsSupported() {
+  assert_implements(
+      'supports' in HTMLScriptElement,
+      'HTMLScriptElement.supports is not supported');
+  assert_implements(
+      HTMLScriptElement.supports('speculationrules'),
+      '<script type="speculationrules"> is not supported');
+}
+
+// Starts prerendering for `url`.
+function startPrerendering(url) {
+  // Adds <script type="speculationrules"> and specifies a prerender candidate
+  // for the given URL.
+  // TODO(https://crbug.com/1174978): <script type="speculationrules"> may not
+  // start prerendering for some reason (e.g., resource limit). Implement a
+  // WebDriver API to force prerendering.
+  const script = document.createElement('script');
+  script.type = 'speculationrules';
+  script.text = `{"prerender": [{"source": "list", "urls": ["${url}"] }] }`;
+  document.head.appendChild(script);
+}
+
+class PrerenderChannel extends EventTarget {
+  #ids = new Set();
+  #url;
+  #active = true;
+
+  constructor(name, uid = new URLSearchParams(location.search).get('uid')) {
+    super();
+    this.#url = `/speculation-rules/prerender/resources/deprecated-broadcast-channel.py?name=${name}&uid=${uid}`;
+    (async() => {
+      while (this.#active) {
+        // Add the "keepalive" option to avoid fetch() results in unhandled
+        // rejection with fetch abortion due to window.close().
+        const messages = await (await fetch(this.#url, {keepalive: true})).json();
+        for (const {data, id} of messages) {
+          if (!this.#ids.has(id))
+            this.dispatchEvent(new MessageEvent('message', {data}));
+          this.#ids.add(id);
+        }
+      }
+    })();
+  }
+
+  close() {
+    this.#active = false;
+  }
+
+  set onmessage(m) {
+    this.addEventListener('message', m)
+  }
+
+  async postMessage(data) {
+    const id = new Date().valueOf();
+    this.#ids.add(id);
+    // Add the "keepalive" option to prevent messages from being lost due to
+    // window.close().
+    await fetch(this.#url, {method: 'POST', body: JSON.stringify({data, id}), keepalive: true});
+  }
+}
+
+// Reads the value specified by `key` from the key-value store on the server.
+async function readValueFromServer(key) {
+  const serverUrl = `${STORE_URL}?key=${key}`;
+  const response = await fetch(serverUrl);
+  if (!response.ok)
+    throw new Error('An error happened in the server');
+  const value = await response.text();
+
+  // The value is not stored in the server.
+  if (value === "")
+    return { status: false };
+
+  return { status: true, value: value };
+}
+
+// Convenience wrapper around the above getter that will wait until a value is
+// available on the server.
+async function nextValueFromServer(key) {
+  let retry = 0;
+  while (true) {
+    // Fetches the test result from the server.
+    let success = true;
+    const { status, value } = await readValueFromServer(key).catch(e => {
+      if (retry++ >= 5) {
+        throw new Error('readValueFromServer failed');
+      }
+      success = false;
+    });
+    if (!success || !status) {
+      // The test result has not been stored yet. Retry after a while.
+      await new Promise(resolve => setTimeout(resolve, 100));
+      continue;
+    }
+
+    return value;
+  }
+}
+
+// Writes `value` for `key` in the key-value store on the server.
+async function writeValueToServer(key, value) {
+  const serverUrl = `${STORE_URL}?key=${key}&value=${value}`;
+  await fetch(serverUrl);
+}
+
+// Loads the initiator page, and navigates to the prerendered page after it
+// receives the 'readyToActivate' message.
+function loadInitiatorPage() {
+  // Used to communicate with the prerendering page.
+  const prerenderChannel = new PrerenderChannel('prerender-channel');
+  window.addEventListener('unload', () => {
+    prerenderChannel.close();
+  });
+
+  // We need to wait for the 'readyToActivate' message before navigation
+  // since the prerendering implementation in Chromium can only activate if the
+  // response for the prerendering navigation has already been received and the
+  // prerendering document was created.
+  const readyToActivate = new Promise((resolve, reject) => {
+    prerenderChannel.addEventListener('message', e => {
+      if (e.data != 'readyToActivate')
+        reject(`The initiator page receives an unsupported message: ${e.data}`);
+      resolve(e.data);
+    });
+  });
+
+  const url = new URL(document.URL);
+  url.searchParams.append('prerendering', '');
+  // Prerender a page that notifies the initiator page of the page's ready to be
+  // activated via the 'readyToActivate'.
+  startPrerendering(url.toString());
+
+  // Navigate to the prerendered page after being informed.
+  readyToActivate.then(() => {
+    window.location = url.toString();
+  }).catch(e => {
+    const testChannel = new PrerenderChannel('test-channel');
+    testChannel.postMessage(
+        `Failed to navigate the prerendered page: ${e.toString()}`);
+    testChannel.close();
+    window.close();
+  });
+}
+
+// Returns messages received from the given PrerenderChannel
+// so that callers do not need to add their own event listeners.
+// nextMessage() returns a promise which resolves with the next message.
+//
+// Usage:
+//   const channel = new PrerenderChannel('channel-name');
+//   const messageQueue = new BroadcastMessageQueue(channel);
+//   const message1 = await messageQueue.nextMessage();
+//   const message2 = await messageQueue.nextMessage();
+//   message1 and message2 are the messages received.
+class BroadcastMessageQueue {
+  constructor(c) {
+    this.messages = [];
+    this.resolveFunctions = [];
+    this.channel = c;
+    this.channel.addEventListener('message', e => {
+      if (this.resolveFunctions.length > 0) {
+        const fn = this.resolveFunctions.shift();
+        fn(e.data);
+      } else {
+        this.messages.push(e.data);
+      }
+    });
+  }
+
+  // Returns a promise that resolves with the next message from this queue.
+  nextMessage() {
+    return new Promise(resolve => {
+      if (this.messages.length > 0)
+        resolve(this.messages.shift())
+      else
+        this.resolveFunctions.push(resolve);
+    });
+  }
+}
+
+// Returns <iframe> element upon load.
+function createFrame(url) {
+  return new Promise(resolve => {
+      const frame = document.createElement('iframe');
+      frame.src = url;
+      frame.onload = () => resolve(frame);
+      document.body.appendChild(frame);
+    });
+}
+
+// `opt` provides additional query params for the prerendered URL.
+// `init_opt` provides additional query params for the page that triggers
+// the prerender.
+// `rule_extras` provides additional parameters for the speculation rule used
+// to trigger prerendering.
+async function create_prerendered_page(t, opt = {}, init_opt = {}, rule_extras = {}) {
+  const baseUrl = '/speculation-rules/prerender/resources/exec.py';
+  const init_uuid = token();
+  const prerender_uuid = token();
+  const discard_uuid = token();
+  const init_remote = new RemoteContext(init_uuid);
+  const prerender_remote = new RemoteContext(prerender_uuid);
+  const discard_remote = new RemoteContext(discard_uuid);
+
+  const init_params = new URLSearchParams(baseUrl.search);
+  init_params.set('uuid', init_uuid);
+  for (const p in init_opt)
+    init_params.set(p, init_opt[p]);
+  window.open(`${baseUrl}?${init_params.toString()}&init`, '_blank', 'noopener');
+
+  const params = new URLSearchParams(baseUrl.search);
+  params.set('uuid', prerender_uuid);
+  params.set('discard_uuid', discard_uuid);
+  for (const p in opt)
+    params.set(p, opt[p]);
+  const url = `${baseUrl}?${params.toString()}`;
+
+  await init_remote.execute_script((url, rule_extras) => {
+      const a = document.createElement('a');
+      a.href = url;
+      a.innerText = 'Activate';
+      document.body.appendChild(a);
+      const rules = document.createElement('script');
+      rules.type = "speculationrules";
+      rules.text = JSON.stringify({prerender: [{source: 'list', urls: [url], ...rule_extras}]});
+      document.head.appendChild(rules);
+  }, [url, rule_extras]);
+
+  await Promise.any([
+    prerender_remote.execute_script(() => {
+        window.import_script_to_prerendered_page = src => {
+            const script = document.createElement('script');
+            script.src = src;
+            document.head.appendChild(script);
+            return new Promise(resolve => script.addEventListener('load', resolve));
+        }
+    }), new Promise(r => t.step_timeout(r, 3000))
+    ]);
+
+  t.add_cleanup(() => {
+    init_remote.execute_script(() => window.close());
+    discard_remote.execute_script(() => window.close());
+    prerender_remote.execute_script(() => window.close());
+  });
+
+  async function tryToActivate() {
+    const prerendering = prerender_remote.execute_script(() => new Promise(resolve => {
+        if (!document.prerendering)
+            resolve('activated');
+        else document.addEventListener('prerenderingchange', () => resolve('activated'));
+    }));
+
+    const discarded = discard_remote.execute_script(() => Promise.resolve('discarded'));
+
+    init_remote.execute_script(url => {
+        location.href = url;
+    }, [url]);
+    return Promise.any([prerendering, discarded]);
+  }
+
+  async function activate() {
+    const prerendering = await tryToActivate();
+    if (prerendering !== 'activated')
+      throw new Error('Should not be prerendering at this point')
+  }
+
+  return {
+    exec: (fn, args) => prerender_remote.execute_script(fn, args),
+    activate,
+    tryToActivate
+  };
+}
+
+
+function test_prerender_restricted(fn, expected, label) {
+  promise_test(async t => {
+    const {exec} = await create_prerendered_page(t);
+    let result = null;
+    try {
+      await exec(fn);
+      result = "OK";
+    } catch (e) {
+      result = e.name;
+    }
+
+    assert_equals(result, expected);
+  }, label);
+}
+
+function test_prerender_defer(fn, label) {
+  promise_test(async t => {
+    const {exec, activate} = await create_prerendered_page(t);
+    let activated = false;
+    const deferred = exec(fn);
+
+    const post = new Promise(resolve =>
+      deferred.then(result => {
+        assert_true(activated, "Deferred operation should occur only after activation");
+        resolve(result);
+      }));
+
+    await activate();
+    activated = true;
+    await post;
+  }, label);
+}
+
+/**
+ * Starts prerendering a page from the given referrer `RemoteContextWrapper`,
+ * using `<script type="speculationrules">`.
+ *
+ * See
+ * /html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
+ * for more details on the `RemoteContextWrapper` framework, and supported fields for extraConfig.
+ *
+ * The returned `RemoteContextWrapper` for the prerendered remote
+ * context will have an extra `url` property, which is used by
+ * @see activatePrerenderRC. (Most `RemoteContextWrapper` uses should not care
+ * about the URL, but prerendering is unique in that you need to navigate to
+ * a prerendered page after creating it.)
+ *
+ * @param {RemoteContextWrapper} referrerRemoteContext
+ * @param {RemoteContextConfig|object} extraConfig
+ * @returns {Promise<RemoteContextWrapper>}
+ */
+async function addPrerenderRC(referrerRemoteContext, extraConfig) {
+  let savedURL;
+  const prerenderedRC = await referrerRemoteContext.helper.createContext({
+    executorCreator(url) {
+      // Save the URL which the remote context helper framework assembled for
+      // us, so that we can attach it to the returned `RemoteContextWrapper`.
+      savedURL = url;
+
+      return referrerRemoteContext.executeScript(url => {
+        const script = document.createElement("script");
+        script.type = "speculationrules";
+        script.textContent = JSON.stringify({
+          prerender: [
+            {
+              source: "list",
+              urls: [url]
+            }
+          ]
+        });
+        document.head.append(script);
+      }, [url]);
+    }, extraConfig
+  });
+
+  prerenderedRC.url = savedURL;
+  return prerenderedRC;
+}
+
+/**
+ * Activates a prerendered RemoteContextWrapper `prerenderedRC` by navigating
+ * the referrer RemoteContextWrapper `referrerRC` to it. If the navigation does
+ * not result in a prerender activation, the returned
+ * promise will be rejected with a testharness.js AssertionError.
+ *
+ * See
+ * /html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
+ * for more on the RemoteContext helper framework.
+ *
+ * @param {RemoteContextWrapper} referrerRC - The referrer
+ *     `RemoteContextWrapper` in which the prerendering was triggered,
+ *     probably via `addPrerenderRC()`.
+ * @param {RemoteContextWrapper} prerenderedRC - The `RemoteContextWrapper`
+ *     pointing to the prerendered content. This is monitored to ensure the
+ *     navigation results in a prerendering activation.
+ * @param {(string) => Promise<undefined>} [navigateFn] - An optional function
+ *     to customize the navigation. It will be passed the URL of the prerendered
+ *     content, and will run as a script in `referrerRC` (see
+ *     `RemoteContextWrapper.prototype.executeScript`). If not given, navigation
+ *     will be done via the `location.href` setter (see
+ *     `RemoteContextWrapper.prototype.navigateTo`).
+ * @returns {Promise<undefined>}
+ */
+async function activatePrerenderRC(referrerRC, prerenderedRC, navigateFn) {
+  // Store a promise that will fulfill when the prerenderingchange event fires.
+  await prerenderedRC.executeScript(() => {
+    window.activatedPromise = new Promise(resolve => {
+      document.addEventListener("prerenderingchange", () => resolve("activated"));
+    });
+  });
+
+  if (navigateFn === undefined) {
+    referrerRC.navigateTo(prerenderedRC.url);
+  } else {
+    referrerRC.navigate(navigateFn, [prerenderedRC.url]);
+  }
+
+  // Wait until that event fires. If the activation fails and a normal
+  // navigation happens instead, then prerenderedRC will start pointing to that
+  // other page, where window.activatedPromise is undefined. In that case this
+  // assert will fail since undefined !== "activated".
+  assert_equals(
+    await prerenderedRC.executeScript(() => window.activatedPromise),
+    "activated",
+    "The prerendered page must be activated; instead a normal navigation happened."
+  );
+}
+
+async function getActivationStart(prerenderedRC) {
+  return await prerenderedRC.executeScript(() => {
+    const entry = performance.getEntriesByType("navigation")[0];
+    return entry.activationStart;
+  });;
+}
+
+// Used by the opened window, to tell the main test runner to terminate a
+// failed test.
+function failTest(reason, uid) {
+  const bc = new PrerenderChannel('test-channel', uid);
+  bc.postMessage({result: 'FAILED', reason});
+  bc.close();
+}