1 files changed, 89 insertions, 0 deletions
diff --git a/browser/base/content/test/tabs/browser_preloadedBrowser_zoom.js b/browser/base/content/test/tabs/browser_preloadedBrowser_zoom.js
new file mode 100644
index 0000000000..698cf82022
--- /dev/null
+++ b/browser/base/content/test/tabs/browser_preloadedBrowser_zoom.js
@@ -0,0 +1,89 @@
+"use strict";
+
+const ZOOM_CHANGE_TOPIC = "browser-fullZoom:location-change";
+
+/**
+ * Helper to check the zoom level of the preloaded browser
+ */
+async function checkPreloadedZoom(level, message) {
+  // Clear up any previous preloaded to test a fresh version
+  NewTabPagePreloading.removePreloadedBrowser(window);
+  NewTabPagePreloading.maybeCreatePreloadedBrowser(window);
+
+  // Wait for zoom handling of preloaded
+  const browser = gBrowser.preloadedBrowser;
+  await new Promise(resolve =>
+    Services.obs.addObserver(function obs(subject) {
+      if (subject === browser) {
+        Services.obs.removeObserver(obs, ZOOM_CHANGE_TOPIC);
+        resolve();
+      }
+    }, ZOOM_CHANGE_TOPIC)
+  );
+
+  is(browser.fullZoom.toFixed(2), level, message);
+
+  // Clean up for other tests
+  NewTabPagePreloading.removePreloadedBrowser(window);
+}
+
+add_task(async function test_default_zoom() {
+  await checkPreloadedZoom("1.00", "default preloaded zoom is 1");
+});
+
+/**
+ * Helper to open about:newtab and zoom then check matching preloaded zoom
+ */
+async function zoomNewTab(changeZoom, message) {
+  const tab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "about:newtab"
+  );
+  changeZoom();
+  const level = tab.linkedBrowser.fullZoom.toFixed(2);
+  BrowserTestUtils.removeTab(tab);
+
+  // Wait for the the update of the full-zoom content pref value, that happens
+  // asynchronously after changing the zoom level.
+  let cps2 = Cc["@mozilla.org/content-pref/service;1"].getService(
+    Ci.nsIContentPrefService2
+  );
+
+  await BrowserTestUtils.waitForCondition(() => {
+    return new Promise(resolve => {
+      cps2.getByDomainAndName(
+        "about:newtab",
+        "browser.content.full-zoom",
+        null,
+        {
+          handleResult(pref) {
+            resolve(level == pref.value);
+          },
+          handleCompletion() {
+            console.log("handleCompletion");
+          },
+        }
+      );
+    });
+  });
+
+  await checkPreloadedZoom(level, `${message}: ${level}`);
+}
+
+add_task(async function test_preloaded_zoom_out() {
+  await zoomNewTab(() => FullZoom.reduce(), "zoomed out applied to preloaded");
+});
+
+add_task(async function test_preloaded_zoom_in() {
+  await zoomNewTab(() => {
+    FullZoom.enlarge();
+    FullZoom.enlarge();
+  }, "zoomed in applied to preloaded");
+});
+
+add_task(async function test_preloaded_zoom_default() {
+  await zoomNewTab(
+    () => FullZoom.reduce(),
+    "zoomed back to default applied to preloaded"
+  );
+});