Bug 1107456 - Part 2: Test that RDM's viewport's outer size values remain unaffected at different zoom levels. r=bradwerth

Depends on D32778

Differential Revision: https://phabricator.services.mozilla.com/D33239

--HG--
extra : moz-landing-system : lando

devtools/client/responsive.html/test/browser/browser.ini

@@ -50,6 +50,7 @@ tags = devtools webextensions
 skip-if = true # Bug 1413765
 [browser_network_throttling.js]
 [browser_orientationchange_event.js]
+[browser_outer_size.js]
 [browser_page_state.js]
 [browser_page_style.js]
 [browser_permission_doorhanger.js]

devtools/client/responsive.html/test/browser/browser_outer_size.js

@@ -0,0 +1,42 @@
+/* Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the window's outerWidth and outerHeight values are not affected by page zoom.
+
+const TEST_URL = "data:text/html;charset=utf-8,";
+const OUTER_WIDTH = 375;
+const OUTER_HEIGHT = 450;
+const ZOOM_LEVELS = [0.3, 0.5, 0.9, 1, 1.5, 2, 2.4];
+
+add_task(async function() {
+  const tab = await addTab(TEST_URL);
+  const browser = tab.linkedBrowser;
+
+  const { ui, manager } = await openRDM(tab);
+  await setViewportSize(ui, manager, OUTER_WIDTH, OUTER_HEIGHT);
+
+  info("Ensure outer size values are unchanged at different zoom levels.");
+  for (let i = 0; i < ZOOM_LEVELS.length; i++) {
+    await checkWindowOuterSize(ui, browser, ZOOM_LEVELS[i]);
+  }
+});
+
+async function checkWindowOuterSize(ui, browser, zoom) {
+  info(`Setting zoom level to ${zoom}`);
+  ZoomManager.setZoomForBrowser(browser, zoom);
+
+  return ContentTask.spawn(ui.getViewportBrowser(),
+    { width: OUTER_WIDTH, height: OUTER_HEIGHT },
+    async function({ width, height }) {
+      // Approximate the outer size value returned on the window content with the expected
+      // value. We should expect, at the very most, a 1px difference between the two due
+      // to floating point rounding errors that occur when scaling from inner size CSS
+      // integer values to outer size CSS integer values. See Part 1 of Bug 1107456.
+      ok(Math.abs(content.outerWidth - width) <= 1,
+        `window.outerWidth should be ${width} and we got ${content.outerWidth}.`);
+      ok(Math.abs(content.outerHeight - height) <= 1,
+        `window.outerHeight should be ${height} and we got ${content.outerHeight}.`);
+    });
+}