1 files changed, 101 insertions, 0 deletions
diff --git a/devtools/client/responsive/test/browser/browser_viewport_zoom_toggle.js b/devtools/client/responsive/test/browser/browser_viewport_zoom_toggle.js
new file mode 100644
index 0000000000..400bfa99a9
--- /dev/null
+++ b/devtools/client/responsive/test/browser/browser_viewport_zoom_toggle.js
@@ -0,0 +1,101 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Verify full zoom levels inherit RDM full zoom after exiting RDM.
+
+const TEST_URL = "https://example.com/";
+
+function getZoomForBrowser(browser) {
+  return ZoomManager.getZoomForBrowser(browser);
+}
+
+function setZoomForBrowser(browser, zoom) {
+  ZoomManager.setZoomForBrowser(browser, zoom);
+}
+
+addRDMTask(
+  null,
+  async function ({ message }) {
+    const INITIAL_ZOOM_LEVEL = 1;
+    const PRE_RDM_ZOOM_LEVEL = 1.5;
+    const MID_RDM_ZOOM_LEVEL = 2;
+
+    const tab = await addTab(TEST_URL);
+    const browser = tab.linkedBrowser;
+
+    await navigateTo(TEST_URL);
+
+    // Get the initial zoom level.
+    const initialOuterZoom = getZoomForBrowser(browser);
+    is(
+      initialOuterZoom,
+      INITIAL_ZOOM_LEVEL,
+      "Initial outer zoom should be " + INITIAL_ZOOM_LEVEL + "."
+    );
+
+    // Change the zoom level before we open RDM.
+    setZoomForBrowser(browser, PRE_RDM_ZOOM_LEVEL);
+
+    const preRDMOuterZoom = getZoomForBrowser(browser);
+    is(
+      preRDMOuterZoom,
+      PRE_RDM_ZOOM_LEVEL,
+      "Pre-RDM outer zoom should be " + PRE_RDM_ZOOM_LEVEL + "."
+    );
+
+    // Start RDM on the tab. This will fundamentally change the way that browser behaves.
+    // It will now pass all of its messages through to the RDM docshell, meaning that when
+    // we request zoom level from it now, we are getting the RDM zoom level.
+    const { ui } = await openRDM(tab);
+    await waitForDeviceAndViewportState(ui);
+
+    const uiDocShell = ui.toolWindow.docShell;
+
+    // Bug 1541692: openRDM behaves differently in the test harness than it does
+    // interactively. Interactively, many features of the container docShell -- including
+    // zoom -- are copied over to the RDM browser. In the test harness, this seems to first
+    // reset the docShell before toggling RDM, which makes checking the initial zoom of the
+    // RDM pane not useful.
+
+    const preZoomUIZoom = uiDocShell.browsingContext.fullZoom;
+    is(
+      preZoomUIZoom,
+      INITIAL_ZOOM_LEVEL,
+      "Pre-zoom UI zoom should be " + INITIAL_ZOOM_LEVEL + "."
+    );
+
+    // Set the zoom level. This should tunnel to the inner browser and leave the UI alone.
+    setZoomForBrowser(browser, MID_RDM_ZOOM_LEVEL);
+
+    // The UI zoom should be unchanged by this.
+    const postZoomUIZoom = uiDocShell.browsingContext.fullZoom;
+    is(
+      postZoomUIZoom,
+      preZoomUIZoom,
+      "UI zoom should be unchanged by RDM zoom."
+    );
+
+    // The RDM zoom should be changed.
+    const finalRDMZoom = getZoomForBrowser(browser);
+    is(
+      finalRDMZoom,
+      MID_RDM_ZOOM_LEVEL,
+      "RDM zoom should be " + MID_RDM_ZOOM_LEVEL + "."
+    );
+
+    // Leave RDM. This should cause the outer pane to take on the full zoom of the RDM pane.
+    await closeRDM(tab);
+
+    const finalOuterZoom = getZoomForBrowser(browser);
+    is(
+      finalOuterZoom,
+      finalRDMZoom,
+      "Final outer zoom should match last RDM zoom."
+    );
+
+    await removeTab(tab);
+  },
+  { onlyPrefAndTask: true }
+);