1 files changed, 42 insertions, 0 deletions
diff --git a/devtools/client/responsive/test/browser/browser_tab_remoteness_change_fission_switch_target.js b/devtools/client/responsive/test/browser/browser_tab_remoteness_change_fission_switch_target.js
new file mode 100644
index 0000000000..0fad9aed2d
--- /dev/null
+++ b/devtools/client/responsive/test/browser/browser_tab_remoteness_change_fission_switch_target.js
@@ -0,0 +1,42 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test for target switching.
+
+const PAGE_ON_CHILD = "http://example.com/";
+const PAGE_ON_MAIN = "about:robots";
+
+const TEST_DPPX = 2;
+
+add_task(async function () {
+  // Set a pref for DPPX in order to assert whether the RDM is working correctly or not.
+  await pushPref("devtools.responsive.viewport.pixelRatio", TEST_DPPX);
+
+  info("Open a page which runs on the child process");
+  const tab = await addTab(PAGE_ON_CHILD);
+  await assertDocshell(tab, false, 0);
+
+  info("Open RDM");
+  await openRDM(tab);
+  await assertDocshell(tab, true, TEST_DPPX);
+
+  info("Load a page which runs on the main process");
+  await navigateTo(PAGE_ON_MAIN);
+  await assertDocshell(tab, true, TEST_DPPX);
+
+  info("Close RDM");
+  await closeRDM(tab);
+  await assertDocshell(tab, false, 0);
+
+  await removeTab(tab);
+});
+
+async function assertDocshell(tab, expectedRDMMode, expectedDPPX) {
+  await asyncWaitUntil(async () => {
+    const { overrideDPPX, inRDMPane } = tab.linkedBrowser.browsingContext;
+    return inRDMPane === expectedRDMMode && overrideDPPX === expectedDPPX;
+  });
+  ok(true, "The state of the docshell is correct");
+}