1 files changed, 157 insertions, 0 deletions
diff --git a/browser/base/content/test/tabs/browser_lazy_tab_browser_events.js b/browser/base/content/test/tabs/browser_lazy_tab_browser_events.js
new file mode 100644
index 0000000000..665bdb7f69
--- /dev/null
+++ b/browser/base/content/test/tabs/browser_lazy_tab_browser_events.js
@@ -0,0 +1,157 @@
+"use strict";
+
+// Helper that watches events that may be triggered when tab browsers are
+// swapped during the test.
+//
+// The primary purpose of this helper is to access tab browser properties
+// during tab events, to verify that there are no undesired side effects, as a
+// regression test for https://bugzilla.mozilla.org/show_bug.cgi?id=1695346
+class TabEventTracker {
+  constructor(tab) {
+    this.tab = tab;
+
+    tab.addEventListener("TabAttrModified", this);
+    tab.addEventListener("TabShow", this);
+    tab.addEventListener("TabHide", this);
+  }
+
+  handleEvent(event) {
+    let description = `${this._expectations.description} at ${event.type}`;
+    if (event.type === "TabAttrModified") {
+      description += `, changed=${event.detail.changed}`;
+    }
+
+    const browser = this.tab.linkedBrowser;
+    is(
+      browser.currentURI.spec,
+      this._expectations.tabUrl,
+      `${description} - expected currentURI`
+    );
+    ok(browser._cachedCurrentURI, `${description} - currentURI was cached`);
+
+    if (event.type === "TabAttrModified") {
+      if (event.detail.changed.includes("muted")) {
+        if (browser.audioMuted) {
+          this._counts.muted++;
+        } else {
+          this._counts.unmuted++;
+        }
+      }
+    } else if (event.type === "TabShow") {
+      this._counts.shown++;
+    } else if (event.type === "TabHide") {
+      this._counts.hidden++;
+    } else {
+      ok(false, `Unexpected event: ${event.type}`);
+    }
+  }
+
+  setExpectations(expectations) {
+    this._expectations = expectations;
+
+    this._counts = {
+      muted: 0,
+      unmuted: 0,
+      shown: 0,
+      hidden: 0,
+    };
+  }
+
+  checkExpectations() {
+    const { description, counters, tabUrl } = this._expectations;
+    Assert.deepEqual(
+      this._counts,
+      counters,
+      `${description} - events observed while swapping tab`
+    );
+    let browser = this.tab.linkedBrowser;
+    is(browser.currentURI.spec, tabUrl, `${description} - tab's currentURI`);
+
+    // Tabs without titles default to URLs without scheme, according to the
+    // logic of tabbrowser.js's setTabTitle/_setTabLabel.
+    // TODO bug 1695512: lazy tabs deviate from that expectation, so the title
+    // is the full URL instead of the URL with the scheme stripped.
+    let tabTitle = tabUrl;
+    is(browser.contentTitle, tabTitle, `${description} - tab's contentTitle`);
+  }
+}
+
+add_task(async function test_hidden_muted_lazy_tabs_and_swapping() {
+  const params = { createLazyBrowser: true };
+  // eslint-disable-next-line @microsoft/sdl/no-insecure-url
+  const URL_HIDDEN = "http://example.com/hide";
+  // eslint-disable-next-line @microsoft/sdl/no-insecure-url
+  const URL_MUTED = "http://example.com/mute";
+  // eslint-disable-next-line @microsoft/sdl/no-insecure-url
+  const URL_NORMAL = "http://example.com/back";
+
+  const lazyTab = BrowserTestUtils.addTab(gBrowser, "", params);
+  const mutedTab = BrowserTestUtils.addTab(gBrowser, URL_MUTED, params);
+  const hiddenTab = BrowserTestUtils.addTab(gBrowser, URL_HIDDEN, params);
+  const normalTab = BrowserTestUtils.addTab(gBrowser, URL_NORMAL, params);
+
+  mutedTab.toggleMuteAudio();
+  gBrowser.hideTab(hiddenTab);
+
+  is(lazyTab.linkedPanel, "", "lazyTab is lazy");
+  is(hiddenTab.linkedPanel, "", "hiddenTab is lazy");
+  is(mutedTab.linkedPanel, "", "mutedTab is lazy");
+  is(normalTab.linkedPanel, "", "normalTab is lazy");
+
+  ok(mutedTab.linkedBrowser.audioMuted, "mutedTab is muted");
+  ok(hiddenTab.hidden, "hiddenTab is hidden");
+  ok(!lazyTab.linkedBrowser.audioMuted, "lazyTab was not muted");
+  ok(!lazyTab.hidden, "lazyTab was not hidden");
+
+  const tabEventTracker = new TabEventTracker(lazyTab);
+
+  tabEventTracker.setExpectations({
+    description: "mutedTab replaced lazyTab (initial)",
+    counters: {
+      muted: 1,
+      unmuted: 0,
+      shown: 0,
+      hidden: 0,
+    },
+    tabUrl: URL_MUTED,
+  });
+  gBrowser.swapBrowsersAndCloseOther(lazyTab, mutedTab);
+  tabEventTracker.checkExpectations();
+  is(lazyTab.linkedPanel, "", "muted lazyTab is still lazy");
+  ok(lazyTab.linkedBrowser.audioMuted, "muted lazyTab is now muted");
+  ok(!lazyTab.hidden, "muted lazyTab is not hidden");
+
+  tabEventTracker.setExpectations({
+    description: "hiddenTab replaced lazyTab/mutedTab",
+    counters: {
+      muted: 0,
+      unmuted: 1,
+      shown: 0,
+      hidden: 1,
+    },
+    tabUrl: URL_HIDDEN,
+  });
+  gBrowser.swapBrowsersAndCloseOther(lazyTab, hiddenTab);
+  tabEventTracker.checkExpectations();
+  is(lazyTab.linkedPanel, "", "hidden lazyTab is still lazy");
+  ok(!lazyTab.linkedBrowser.audioMuted, "hidden lazyTab is not muted any more");
+  ok(lazyTab.hidden, "hidden lazyTab has been hidden");
+
+  tabEventTracker.setExpectations({
+    description: "normalTab replaced lazyTab/hiddenTab",
+    counters: {
+      muted: 0,
+      unmuted: 0,
+      shown: 1,
+      hidden: 0,
+    },
+    tabUrl: URL_NORMAL,
+  });
+  gBrowser.swapBrowsersAndCloseOther(lazyTab, normalTab);
+  tabEventTracker.checkExpectations();
+  is(lazyTab.linkedPanel, "", "normal lazyTab is still lazy");
+  ok(!lazyTab.linkedBrowser.audioMuted, "normal lazyTab is not muted any more");
+  ok(!lazyTab.hidden, "normal lazyTab is not hidden any more");
+
+  BrowserTestUtils.removeTab(lazyTab);
+});