diff -r 000000000000 -r 6474c204b198 browser/devtools/webconsole/test/browser_webconsole_bug_585237_line_limit.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/webconsole/test/browser_webconsole_bug_585237_line_limit.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,106 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ *
+ * Contributor(s):
+ *  Patrick Walton <pcwalton@mozilla.com>
+ *  Mihai Șucan <mihai.sucan@gmail.com>
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+// Tests that the Web Console limits the number of lines displayed according to
+// the user's preferences.
+
+const TEST_URI = "data:text/html;charset=utf8,test for bug 585237";
+let hud, testDriver;
+
+function test() {
+  addTab(TEST_URI);
+  browser.addEventListener("load", function onLoad() {
+    browser.removeEventListener("load", onLoad, true);
+    openConsole(null, function(aHud) {
+      hud = aHud;
+      testDriver = testGen();
+      testNext();
+    });
+  }, true);
+}
+
+function testNext() {
+  testDriver.next();
+}
+
+function testGen() {
+  let console = content.console;
+  outputNode = hud.outputNode;
+
+  hud.jsterm.clearOutput();
+
+  let prefBranch = Services.prefs.getBranch("devtools.hud.loglimit.");
+  prefBranch.setIntPref("console", 20);
+
+  for (let i = 0; i < 30; i++) {
+    console.log("foo #" + i); // must change message to prevent repeats
+  }
+
+  waitForMessages({
+    webconsole: hud,
+    messages: [{
+      text: "foo #29",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_LOG,
+    }],
+  }).then(testNext);
+
+  yield undefined;
+
+  is(countMessageNodes(), 20, "there are 20 message nodes in the output " +
+     "when the log limit is set to 20");
+
+  console.log("bar bug585237");
+
+  waitForMessages({
+    webconsole: hud,
+    messages: [{
+      text: "bar bug585237",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_LOG,
+    }],
+  }).then(testNext);
+
+  yield undefined;
+
+  is(countMessageNodes(), 20, "there are still 20 message nodes in the " +
+     "output when adding one more");
+
+  prefBranch.setIntPref("console", 30);
+  for (let i = 0; i < 20; i++) {
+    console.log("boo #" + i); // must change message to prevent repeats
+  }
+
+  waitForMessages({
+    webconsole: hud,
+    messages: [{
+      text: "boo #19",
+      category: CATEGORY_WEBDEV,
+      severity: SEVERITY_LOG,
+    }],
+  }).then(testNext);
+
+  yield undefined;
+
+  is(countMessageNodes(), 30, "there are 30 message nodes in the output " +
+     "when the log limit is set to 30");
+
+  prefBranch.clearUserPref("console");
+  hud = testDriver = prefBranch = console = outputNode = null;
+  finishTest();
+
+  yield undefined;
+}
+
+function countMessageNodes() {
+  return outputNode.querySelectorAll(".message").length;
+}
+