some progress on affix plugin

js/tests/unit/bootstrap-affix.js

@@ -0,0 +1,25 @@
+$(function () {
+
+    module("bootstrap-affix")
+
+      test("should be defined on jquery object", function () {
+        ok($(document.body).affix, 'affix method is defined')
+      })
+
+      test("should return element", function () {
+        ok($(document.body).affix()[0] == document.body, 'document.body returned')
+      })
+
+      test("should exit early if element is not visible", function () {
+        var $affix = $('<div style="display: none"></div>').affix()
+        $affix.data('affix').checkPosition()
+        ok(!$affix.hasClass('affix'), 'affix class was not added')
+      })
+
+      test("should add affix class if scrolled to correct position", function () {
+        var $affix = $('<div></div>').appendTo('body').affix()
+        $('body').trigger('scroll')
+        ok($affix.hasClass('affix'), 'element has class affix')
+      })
+
+})