diff -r 000000000000 -r 6474c204b198 browser/devtools/sourceeditor/test/browser_editor_movelines.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/sourceeditor/test/browser_editor_movelines.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,62 @@
+/* vim: set ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function test() {
+  waitForExplicitFinish();
+  setup((ed, win) => {
+    var simpleProg = "function foo() {\n  let i = 1;\n  let j = 2;\n  return bar;\n}";
+    ed.setText(simpleProg);
+
+    // Move first line up
+    ed.setCursor({ line: 0, ch: 0 });
+    ed.moveLineUp();
+    is(ed.getText(0), "function foo() {", "getText(num)");
+    ch(ed.getCursor(), { line: 0, ch: 0 }, "getCursor");
+
+    // Move last line down
+    ed.setCursor({ line: 4, ch: 0 });
+    ed.moveLineDown();
+    is(ed.getText(4), "}", "getText(num)");
+    ch(ed.getCursor(), { line: 4, ch: 0 }, "getCursor");
+
+    // Move line 2 up
+    ed.setCursor({ line: 1, ch: 5});
+    ed.moveLineUp();
+    is(ed.getText(0), "  let i = 1;", "getText(num)");
+    is(ed.getText(1), "function foo() {", "getText(num)");
+    ch(ed.getCursor(), { line: 0, ch: 5 }, "getCursor");
+
+    // Undo previous move by moving line 1 down
+    ed.moveLineDown();
+    is(ed.getText(0), "function foo() {", "getText(num)");
+    is(ed.getText(1), "  let i = 1;", "getText(num)");
+    ch(ed.getCursor(), { line: 1, ch: 5 }, "getCursor");
+
+    // Move line 2 and 3 up
+    ed.setSelection({ line: 1, ch: 0 }, { line: 2, ch: 0 });
+    ed.moveLineUp();
+    is(ed.getText(0), "  let i = 1;", "getText(num)");
+    is(ed.getText(1), "  let j = 2;", "getText(num)");
+    is(ed.getText(2), "function foo() {", "getText(num)");
+    ch(ed.getCursor("start"), { line: 0, ch: 0 }, "getCursor(string)");
+    ch(ed.getCursor("end"), { line: 1, ch: 0 }, "getCursor(string)");
+
+    // Move line 1 to 3 down twice
+    ed.dropSelection();
+    ed.setSelection({ line: 0, ch: 7 }, { line: 2, ch: 5 });
+    ed.moveLineDown();
+    ed.moveLineDown();
+    is(ed.getText(0), "  return bar;", "getText(num)");
+    is(ed.getText(1), "}", "getText(num)");
+    is(ed.getText(2), "  let i = 1;", "getText(num)");
+    is(ed.getText(3), "  let j = 2;", "getText(num)");
+    is(ed.getText(4), "function foo() {", "getText(num)");
+    ch(ed.getCursor("start"), { line: 2, ch: 7 }, "getCursor(string)");
+    ch(ed.getCursor("end"), { line: 4, ch: 5 }, "getCursor(string)");
+
+    teardown(ed, win);
+  });
+}