diff -r 000000000000 -r 6474c204b198 browser/devtools/netmonitor/test/browser_net_pane-collapse.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/netmonitor/test/browser_net_pane-collapse.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,66 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests if the network monitor panes collapse properly.
+ */
+
+function test() {
+  initNetMonitor(SIMPLE_URL).then(([aTab, aDebuggee, aMonitor]) => {
+    info("Starting test... ");
+
+    let { document, Prefs, NetMonitorView } = aMonitor.panelWin;
+    let detailsPane = document.getElementById("details-pane");
+    let detailsPaneToggleButton = document.getElementById("details-pane-toggle");
+
+    ok(detailsPane.hasAttribute("pane-collapsed") &&
+       detailsPaneToggleButton.hasAttribute("pane-collapsed"),
+      "The details pane should initially be hidden.");
+
+    NetMonitorView.toggleDetailsPane({ visible: true, animated: false });
+
+    let width = ~~(detailsPane.getAttribute("width"));
+    is(width, Prefs.networkDetailsWidth,
+      "The details pane has an incorrect width.");
+    is(detailsPane.style.marginLeft, "0px",
+      "The details pane has an incorrect left margin.");
+    is(detailsPane.style.marginRight, "0px",
+      "The details pane has an incorrect right margin.");
+    ok(!detailsPane.hasAttribute("animated"),
+      "The details pane has an incorrect animated attribute.");
+    ok(!detailsPane.hasAttribute("pane-collapsed") &&
+       !detailsPaneToggleButton.hasAttribute("pane-collapsed"),
+      "The details pane should at this point be visible.");
+
+    NetMonitorView.toggleDetailsPane({ visible: false, animated: true });
+
+    let margin = -(width + 1) + "px";
+    is(width, Prefs.networkDetailsWidth,
+      "The details pane has an incorrect width after collapsing.");
+    is(detailsPane.style.marginLeft, margin,
+      "The details pane has an incorrect left margin after collapsing.");
+    is(detailsPane.style.marginRight, margin,
+      "The details pane has an incorrect right margin after collapsing.");
+    ok(detailsPane.hasAttribute("animated"),
+      "The details pane has an incorrect attribute after an animated collapsing.");
+    ok(detailsPane.hasAttribute("pane-collapsed") &&
+       detailsPaneToggleButton.hasAttribute("pane-collapsed"),
+      "The details pane should not be visible after collapsing.");
+
+    NetMonitorView.toggleDetailsPane({ visible: true, animated: false });
+
+    is(width, Prefs.networkDetailsWidth,
+      "The details pane has an incorrect width after uncollapsing.");
+    is(detailsPane.style.marginLeft, "0px",
+      "The details pane has an incorrect left margin after uncollapsing.");
+    is(detailsPane.style.marginRight, "0px",
+      "The details pane has an incorrect right margin after uncollapsing.");
+    ok(!detailsPane.hasAttribute("animated"),
+      "The details pane has an incorrect attribute after an unanimated uncollapsing.");
+    ok(!detailsPane.hasAttribute("pane-collapsed") &&
+       !detailsPaneToggleButton.hasAttribute("pane-collapsed"),
+      "The details pane should be visible again after uncollapsing.");
+
+    teardown(aMonitor).then(finish);
+  });
+}