1 files changed, 93 insertions, 0 deletions
diff --git a/devtools/client/responsive/test/browser/browser_window_sizing.js b/devtools/client/responsive/test/browser/browser_window_sizing.js
new file mode 100644
index 0000000000..6b8a558813
--- /dev/null
+++ b/devtools/client/responsive/test/browser/browser_window_sizing.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests that correct window sizing values are reported and unaffected by zoom. In
+// particular, we want to ensure that the values for the window's outer and screen
+// sizing values reflect the size of the viewport.
+
+const TEST_URL = "data:text/html;charset=utf-8,";
+const WIDTH = 375;
+const HEIGHT = 450;
+const ZOOM_LEVELS = [0.3, 0.5, 0.9, 1, 1.5, 2, 2.4];
+
+addRDMTask(
+  null,
+  async function () {
+    const tab = await addTab(TEST_URL);
+    const browser = tab.linkedBrowser;
+
+    const { ui, manager } = await openRDM(tab);
+    await waitForDeviceAndViewportState(ui);
+    await setViewportSize(ui, manager, WIDTH, HEIGHT);
+
+    info("Ensure outer size values are unchanged at different zoom levels.");
+    for (let i = 0; i < ZOOM_LEVELS.length; i++) {
+      info(`Setting zoom level to ${ZOOM_LEVELS[i]}`);
+      await promiseRDMZoom(ui, browser, ZOOM_LEVELS[i]);
+
+      await checkWindowOuterSize(ui, ZOOM_LEVELS[i]);
+      await checkWindowScreenSize(ui, ZOOM_LEVELS[i]);
+    }
+  },
+  { onlyPrefAndTask: true }
+);
+
+async function checkWindowOuterSize(ui, zoom_level) {
+  return SpecialPowers.spawn(
+    ui.getViewportBrowser(),
+    [{ width: WIDTH, height: HEIGHT, zoom: zoom_level }],
+    async function ({ width, height, zoom }) {
+      // Approximate the outer size value returned on the window content with the expected
+      // value. We should expect, at the very most, a 2px 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.
+      // Some of the drift is also due to full zoom scaling effects; see Bug 1577775.
+      Assert.lessOrEqual(
+        Math.abs(content.outerWidth - width),
+        2,
+        `window.outerWidth zoom ${zoom} should be ${width} and we got ${content.outerWidth}.`
+      );
+      Assert.lessOrEqual(
+        Math.abs(content.outerHeight - height),
+        2,
+        `window.outerHeight zoom ${zoom} should be ${height} and we got ${content.outerHeight}.`
+      );
+    }
+  );
+}
+
+async function checkWindowScreenSize(ui, zoom_level) {
+  return SpecialPowers.spawn(
+    ui.getViewportBrowser(),
+    [{ width: WIDTH, height: HEIGHT, zoom: zoom_level }],
+    async function ({ width, height, zoom }) {
+      const { screen } = content;
+
+      Assert.lessOrEqual(
+        Math.abs(screen.availWidth - width),
+        2,
+        `screen.availWidth zoom ${zoom} should be ${width} and we got ${screen.availWidth}.`
+      );
+
+      Assert.lessOrEqual(
+        Math.abs(screen.availHeight - height),
+        2,
+        `screen.availHeight zoom ${zoom} should be ${height} and we got ${screen.availHeight}.`
+      );
+
+      Assert.lessOrEqual(
+        Math.abs(screen.width - width),
+        2,
+        `screen.width zoom " ${zoom} should be ${width} and we got ${screen.width}.`
+      );
+
+      Assert.lessOrEqual(
+        Math.abs(screen.height - height),
+        2,
+        `screen.height zoom " ${zoom} should be ${height} and we got ${screen.height}.`
+      );
+    }
+  );
+}