--- a/devtools/client/framework/test/browser.ini
+++ b/devtools/client/framework/test/browser.ini
@@ -59,16 +59,17 @@ skip-if = true # Bug 1177463 - Temporari
 [browser_toolbox_select_event.js]
 skip-if = e10s # Bug 1069044 - destroyInspector may hang during shutdown
 [browser_toolbox_selected_tool_unavailable.js]
 [browser_toolbox_sidebar.js]
 [browser_toolbox_sidebar_events.js]
 [browser_toolbox_sidebar_existing_tabs.js]
 [browser_toolbox_sidebar_overflow_menu.js]
 [browser_toolbox_split_console.js]
+[browser_toolbox_target.js]
 [browser_toolbox_tabsswitch_shortcuts.js]
 [browser_toolbox_textbox_context_menu.js]
 [browser_toolbox_theme_registration.js]
 [browser_toolbox_toggle.js]
 [browser_toolbox_tool_ready.js]
 [browser_toolbox_tool_remote_reopen.js]
 [browser_toolbox_transport_events.js]
 [browser_toolbox_view_source_01.js]

new file mode 100644
--- /dev/null
+++ b/devtools/client/framework/test/browser_toolbox_target.js
@@ -0,0 +1,60 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test about:devtools-toolbox?target which allows opening a toolbox in an
+// iframe while defining which document to debug by setting a `target`
+// attribute refering to the document to debug.
+
+add_task(function *() {
+  // iframe loads the document to debug
+  let iframe = document.createElement("browser");
+  iframe.setAttribute("type", "content");
+  document.documentElement.appendChild(iframe);
+
+  let onLoad = once(iframe, "load", true);
+  iframe.setAttribute("src", "data:text/html,document to debug");
+  yield onLoad;
+  is(iframe.contentWindow.document.body.innerHTML, "document to debug");
+
+  // toolbox loads the toolbox document
+  let toolboxIframe = document.createElement("iframe");
+  document.documentElement.appendChild(toolboxIframe);
+
+  // Important step to define which target to debug
+  toolboxIframe.target = iframe;
+
+  let onToolboxReady = gDevTools.once("toolbox-ready");
+
+  onLoad = once(toolboxIframe, "load", true);
+  toolboxIframe.setAttribute("src", "about:devtools-toolbox?target");
+  yield onLoad;
+
+  // Also wait for toolbox-ready, as toolbox document load isn't enough, there
+  // is plenty of asynchronous steps during toolbox load
+  info("Waiting for toolbox-ready");
+  let toolbox = yield onToolboxReady;
+
+  let onToolboxDestroyed = gDevTools.once("toolbox-destroyed");
+  let onTabActorDetached = once(toolbox.target.client, "tabDetached");
+
+  info("Removing the iframes");
+  toolboxIframe.remove();
+
+  // And wait for toolbox-destroyed as toolbox unload is also full of
+  // asynchronous operation that outlast unload event
+  info("Waiting for toolbox-destroyed");
+  yield onToolboxDestroyed;
+  info("Toolbox destroyed");
+
+  // Also wait for tabDetached. Toolbox destroys the Target which calls
+  // TabActor.detach(). But Target doesn't wait for detach's end to resolve.
+  // Whereas it is quite important as it is a significant part of toolbox
+  // cleanup. If we do not wait for it and starts removing debugged document,
+  // the actor is still considered as being attached and continues processing
+  // events.
+  yield onTabActorDetached;
+
+  iframe.remove();
+});