diff -r 000000000000 -r 6474c204b198 browser/devtools/netmonitor/test/browser_net_image-tooltip.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/netmonitor/test/browser_net_image-tooltip.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,77 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests if image responses show a popup in the requests menu when hovered.
+ */
+
+function test() {
+  initNetMonitor(CONTENT_TYPE_WITHOUT_CACHE_URL).then(([aTab, aDebuggee, aMonitor]) => {
+    info("Starting test... ");
+
+    let { $, EVENTS, ACTIVITY_TYPE, NetMonitorView, NetMonitorController } = aMonitor.panelWin;
+    let { RequestsMenu } = NetMonitorView;
+
+    promise.all([
+      waitForNetworkEvents(aMonitor, 6),
+      waitFor(aMonitor.panelWin, EVENTS.RESPONSE_IMAGE_THUMBNAIL_DISPLAYED)
+    ]).then(() => {
+      info("Checking the image thumbnail after a few requests were made...");
+      let requestItem = RequestsMenu.items[5];
+      let requestTooltip = requestItem.attachment.tooltip;
+      ok(requestTooltip, "There should be a tooltip instance for the image request.");
+
+      let anchor = $(".requests-menu-file", requestItem.target);
+      return showTooltipOn(requestTooltip, anchor);
+    }).then(aTooltip => {
+      ok(true,
+        "An tooltip was successfully opened for the image request.");
+      is(aTooltip.content.querySelector("image").src, TEST_IMAGE_DATA_URI,
+        "The tooltip's image content is displayed correctly.");
+
+      info("Reloading the debuggee and performing all requests again...");
+      reloadAndPerformRequests();
+
+      return promise.all([
+        waitForNetworkEvents(aMonitor, 7), // 6 + 1
+        waitFor(aMonitor.panelWin, EVENTS.RESPONSE_IMAGE_THUMBNAIL_DISPLAYED)
+      ]);
+    }).then(() => {
+      info("Checking the image thumbnail after a reload.");
+      let requestItem = RequestsMenu.items[6];
+      let requestTooltip = requestItem.attachment.tooltip;
+      ok(requestTooltip, "There should be a tooltip instance for the image request.");
+
+      let anchor = $(".requests-menu-file", requestItem.target);
+      return showTooltipOn(requestTooltip, anchor);
+    }).then(aTooltip => {
+      ok(true,
+        "An tooltip was successfully opened for the image request.");
+      is(aTooltip.content.querySelector("image").src, TEST_IMAGE_DATA_URI,
+        "The tooltip's image content is displayed correctly.");
+
+      teardown(aMonitor).then(finish);
+    });
+
+    function reloadAndPerformRequests() {
+      NetMonitorController.triggerActivity(ACTIVITY_TYPE.RELOAD.WITH_CACHE_ENABLED).then(() => {
+        aDebuggee.performRequests();
+      });
+    }
+
+    /**
+     * @return a promise that resolves when the tooltip is shown
+     */
+    function showTooltipOn(tooltip, element) {
+      return Task.spawn(function*() {
+        let isTarget = yield tooltip.isValidHoverTarget(element);
+        let onShown = tooltip.once("shown");
+        tooltip.show();
+        yield onShown;
+        return tooltip;
+      });
+    }
+
+    aDebuggee.performRequests();
+  });
+}