--- a/devtools/client/framework/test/browser.ini
+++ b/devtools/client/framework/test/browser.ini
@@ -101,16 +101,17 @@ skip-if = e10s # Bug 1069044 - destroyIn
 [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_telemetry_close.js]
+[browser_toolbox_telemetry_enter.js]
 [browser_toolbox_textbox_context_menu.js]
 [browser_toolbox_theme.js]
 [browser_toolbox_theme_registration.js]
 [browser_toolbox_toggle.js]
 [browser_toolbox_tool_ready.js]
 [browser_toolbox_tool_remote_reopen.js]
 [browser_toolbox_toolbar_overflow.js]
 [browser_toolbox_toolbar_reorder_by_dnd.js]

new file mode 100644
--- /dev/null
+++ b/devtools/client/framework/test/browser_toolbox_telemetry_enter.js
@@ -0,0 +1,148 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const URL = "data:text/html;charset=utf8,browser_toolbox_telemetry_enter.js";
+const OPTOUT = Ci.nsITelemetry.DATASET_RELEASE_CHANNEL_OPTOUT;
+const DATA = [
+  {
+    timestamp: null,
+    category: "devtools.main",
+    method: "enter",
+    object: "inspector",
+    value: null,
+    extra: {
+      host: "bottom",
+      width: "1300",
+      start_state: "initial_panel",
+      panel_name: "inspector",
+      cold: "true"
+    }
+  }, {
+    timestamp: null,
+    category: "devtools.main",
+    method: "enter",
+    object: "jsdebugger",
+    value: null,
+    extra: {
+      host: "bottom",
+      width: "1300",
+      start_state: "toolbox_show",
+      panel_name: "jsdebugger",
+      cold: "true"
+    }
+  }, {
+    timestamp: null,
+    category: "devtools.main",
+    method: "enter",
+    object: "styleeditor",
+    value: null,
+    extra: {
+      host: "bottom",
+      width: "1300",
+      start_state: "toolbox_show",
+      panel_name: "styleeditor",
+      cold: "true"
+    }
+  }, {
+    timestamp: null,
+    category: "devtools.main",
+    method: "enter",
+    object: "netmonitor",
+    value: null,
+    extra: {
+      host: "bottom",
+      width: "1300",
+      start_state: "toolbox_show",
+      panel_name: "netmonitor",
+      cold: "true"
+    }
+  }, {
+    timestamp: null,
+    category: "devtools.main",
+    method: "enter",
+    object: "storage",
+    value: null,
+    extra: {
+      host: "bottom",
+      width: "1300",
+      start_state: "toolbox_show",
+      panel_name: "storage",
+      cold: "true"
+    }
+  }, {
+    timestamp: null,
+    category: "devtools.main",
+    method: "enter",
+    object: "netmonitor",
+    value: null,
+    extra: {
+      host: "bottom",
+      width: "1300",
+      start_state: "toolbox_show",
+      panel_name: "netmonitor",
+      cold: "false"
+    }
+  }
+];
+
+add_task(async function() {
+  // Let's reset the counts.
+  Services.telemetry.clearEvents();
+
+  // Ensure no events have been logged
+  const snapshot = Services.telemetry.snapshotEvents(OPTOUT, true);
+  ok(!snapshot.parent, "No events have been logged for the main process");
+
+  const tab = await addTab(URL);
+  const target = TargetFactory.forTab(tab);
+
+  // Set up some cached messages for the web console.
+  await ContentTask.spawn(tab.linkedBrowser, {}, () => {
+    content.console.log("test 1");
+    content.console.log("test 2");
+    content.console.log("test 3");
+    content.console.log("test 4");
+    content.console.log("test 5");
+  });
+
+  // Open the toolbox
+  await gDevTools.showToolbox(target, "inspector");
+
+  // Switch between a few tools
+  await gDevTools.showToolbox(target, "jsdebugger");
+  await gDevTools.showToolbox(target, "styleeditor");
+  await gDevTools.showToolbox(target, "netmonitor");
+  await gDevTools.showToolbox(target, "storage");
+  await gDevTools.showToolbox(target, "netmonitor");
+
+  await checkResults();
+});
+
+async function checkResults() {
+  const snapshot = Services.telemetry.snapshotEvents(OPTOUT, true);
+  const events = snapshot.parent.filter(event => event[1] === "devtools.main" &&
+                                                 event[2] === "enter" &&
+                                                 event[4] === null
+  );
+
+  for (let i in DATA) {
+    const [ timestamp, category, method, object, value, extra ] = events[i];
+    const expected = DATA[i];
+
+    // ignore timestamp
+    ok(timestamp > 0, "timestamp is greater than 0");
+    is(category, expected.category, "category is correct");
+    is(method, expected.method, "method is correct");
+    is(object, expected.object, "object is correct");
+    is(value, expected.value, "value is correct");
+
+    // extras
+    is(extra.host, expected.extra.host, "host is correct");
+    ok(extra.width > 0, "width is greater than 0");
+    is(extra.start_state, expected.extra.start_state, "start_state is correct");
+    is(extra.panel_name, expected.extra.panel_name, "panel_name is correct");
+    is(extra.cold, expected.extra.cold, "cold is correct");
+  }
+}