diff -r 000000000000 -r 6474c204b198 browser/devtools/webconsole/test/browser_webconsole_assert.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/webconsole/test/browser_webconsole_assert.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,50 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that console.assert() works as expected (i.e. outputs only on falsy
+// asserts). See bug 760193.
+
+const TEST_URI = "http://example.com/browser/browser/devtools/webconsole/test/test-console-assert.html";
+
+function test() {
+  addTab(TEST_URI);
+  browser.addEventListener("load", function onLoad() {
+    browser.removeEventListener("load", onLoad, true);
+    openConsole(null, consoleOpened);
+  }, true);
+}
+
+function consoleOpened(hud) {
+  waitForMessages({
+    webconsole: hud,
+    messages: [{
+      text: "start",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_LOG,
+    },
+    {
+      text: "false assert",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_ERROR,
+    },
+    {
+      text: "falsy assert",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_ERROR,
+    },
+    {
+      text: "end",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_LOG,
+    }],
+  }).then(() => {
+    let nodes = hud.outputNode.querySelectorAll(".message");
+    is(nodes.length, 4, "only four messages are displayed, no output from the true assert");
+    finishTest();
+  });
+
+  let button = content.document.querySelector("button");
+  ok(button, "we have the button");
+  EventUtils.sendMouseEvent({ type: "click" }, button, content);
+}