1 files changed, 129 insertions, 0 deletions
diff --git a/browser/components/extensions/test/browser/browser_ext_tabs_discard_reversed.js b/browser/components/extensions/test/browser/browser_ext_tabs_discard_reversed.js
new file mode 100644
index 0000000000..5fad30a6fb
--- /dev/null
+++ b/browser/components/extensions/test/browser/browser_ext_tabs_discard_reversed.js
@@ -0,0 +1,129 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function tabs_discarded_load_and_discard() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      permissions: ["tabs", "webNavigation"],
+    },
+    async background() {
+      browser.test.sendMessage("ready");
+      const SHIP = await new Promise(resolve =>
+        browser.test.onMessage.addListener((msg, data) => {
+          resolve(data);
+        })
+      );
+
+      const PAGE_URL_BEFORE = "http://example.com/initiallyDiscarded";
+      const PAGE_URL =
+        "http://example.com/browser/browser/components/extensions/test/browser/file_dummy.html";
+      // Tabs without titles default to URLs without scheme, according to the
+      // logic of tabbrowser.js's setTabTitle/_setTabLabel.
+      // TODO bug 1695512: discarded tabs should also follow this logic instead
+      // of using the unmodified original URL.
+      const PAGE_TITLE_BEFORE = PAGE_URL_BEFORE;
+      const PAGE_TITLE_INITIAL = PAGE_URL.replace("http://", "");
+      const PAGE_TITLE = "Dummy test page";
+
+      function assertDeepEqual(expected, actual, message) {
+        browser.test.assertDeepEq(expected, actual, message);
+      }
+
+      let tab = await browser.tabs.create({
+        url: PAGE_URL_BEFORE,
+        discarded: true,
+      });
+      const TAB_ID = tab.id;
+      browser.test.assertTrue(tab.discarded, "Tab initially discarded");
+      browser.test.assertEq(PAGE_URL_BEFORE, tab.url, "Initial URL");
+      browser.test.assertEq(PAGE_TITLE_BEFORE, tab.title, "Initial title");
+
+      const observedChanges = {
+        discarded: [],
+        title: [],
+        url: [],
+      };
+      function tabsOnUpdatedAfterLoad(tabId, changeInfo, tab) {
+        browser.test.assertEq(TAB_ID, tabId, "tabId for tabs.onUpdated");
+        for (let [prop, value] of Object.entries(changeInfo)) {
+          observedChanges[prop].push(value);
+        }
+      }
+      browser.tabs.onUpdated.addListener(tabsOnUpdatedAfterLoad, {
+        properties: ["discarded", "url", "title"],
+      });
+
+      // Load new URL to transition from discarded:true to discarded:false.
+      await new Promise(resolve => {
+        browser.webNavigation.onCompleted.addListener(details => {
+          browser.test.assertEq(TAB_ID, details.tabId, "onCompleted for tab");
+          browser.test.assertEq(PAGE_URL, details.url, "URL ater load");
+          resolve();
+        });
+        browser.tabs.update(TAB_ID, { url: PAGE_URL });
+      });
+      assertDeepEqual(
+        [false],
+        observedChanges.discarded,
+        "changes to tab.discarded after update"
+      );
+      // TODO bug 1669356: the tabs.onUpdated events should only see the
+      // requested URL and its title. However, the current implementation
+      // reports several events (including url/title "changes") as part of
+      // "restoring" the lazy browser prior to loading the requested URL.
+
+      let expectedUrlChanges = [PAGE_URL_BEFORE, PAGE_URL];
+      if (SHIP && observedChanges.url.length === 1) {
+        // Except when SHIP is enabled, which turns this into a race,
+        // so sometimes only the final URL is seen (see bug 1696815#c22).
+        expectedUrlChanges = [PAGE_URL];
+      }
+
+      assertDeepEqual(
+        expectedUrlChanges,
+        observedChanges.url,
+        "changes to tab.url after update"
+      );
+      assertDeepEqual(
+        [PAGE_TITLE_INITIAL, PAGE_TITLE],
+        observedChanges.title,
+        "changes to tab.title after update"
+      );
+
+      tab = await browser.tabs.get(TAB_ID);
+      browser.test.assertFalse(tab.discarded, "tab.discarded after load");
+      browser.test.assertEq(PAGE_URL, tab.url, "tab.url after load");
+      browser.test.assertEq(PAGE_TITLE, tab.title, "tab.title after load");
+
+      // Reset counters.
+      observedChanges.discarded.length = 0;
+      observedChanges.title.length = 0;
+      observedChanges.url.length = 0;
+
+      // Transition from discarded:false to discarded:true
+      await browser.tabs.discard(TAB_ID);
+      assertDeepEqual(
+        [true],
+        observedChanges.discarded,
+        "changes to tab.discarded after discard"
+      );
+      assertDeepEqual([], observedChanges.url, "tab.url not changed");
+      assertDeepEqual([], observedChanges.title, "tab.title not changed");
+
+      tab = await browser.tabs.get(TAB_ID);
+      browser.test.assertTrue(tab.discarded, "tab.discarded after discard");
+      browser.test.assertEq(PAGE_URL, tab.url, "tab.url after discard");
+      browser.test.assertEq(PAGE_TITLE, tab.title, "tab.title after discard");
+
+      await browser.tabs.remove(TAB_ID);
+      browser.test.sendMessage("done");
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitMessage("ready");
+  extension.sendMessage("SHIP", Services.appinfo.sessionHistoryInParent);
+  await extension.awaitMessage("done");
+  await extension.unload();
+});