Add a couple of tests for anchor buttons

1. It should trigger with a space key
2. It shouldn’t trigger with a tab key

spec/manifest.js

@@ -4,6 +4,7 @@ var manifest = {
     '../../node_modules/jquery/dist/jquery.js',
     '../../javascripts/govuk/modules.js',
     '../../javascripts/govuk/modules/auto-track-event.js',
+    '../../javascripts/govuk/anchor-buttons.js',
     '../../javascripts/govuk/multivariate-test.js',
     '../../javascripts/govuk/primary-links.js',
     '../../javascripts/govuk/stick-at-top-when-scrolling.js',
@@ -19,6 +20,7 @@ var manifest = {
   test : [
     '../unit/modules.spec.js',
     '../unit/Modules/auto-track-event.spec.js',
+    '../unit/anchor-button.spec.js',
     '../unit/multivariate-test.spec.js',
     '../unit/primary-links.spec.js',
     '../unit/stick-at-top-when-scrolling.spec.js',

spec/unit/anchor-button.spec.js

@@ -0,0 +1,34 @@
+describe("anchor-buttons", function () {
+  var $body;
+  var $anchorButton;
+  var keyupEvent;
+
+  beforeEach(function () {
+    $anchorButton = $('<a role="button">Button</a>');
+    $anchorButton.on('click',function(){
+      $anchorButton.addClass('clicked');
+    });
+    $(document.body).append($anchorButton);
+    keyupEvent = $.Event('keyup');
+    keyupEvent.target = $anchorButton.get(0);
+    GOVUK.anchorButtons.init();
+  });
+
+  afterEach(function () {
+    $anchorButton.remove();
+    $(document).off('keyup');
+  });
+
+  it('should trigger event on space', function(){
+    keyupEvent.which = 32; // Space character
+    $(document).trigger(keyupEvent);
+    expect($anchorButton.hasClass('clicked')).toBe(true);
+  });
+
+  it('should not trigger event on tab', function(){
+    keyupEvent.which = 9; // Tab character
+    $(document).trigger(keyupEvent);
+    expect($anchorButton.hasClass('clicked')).toBe(false);
+  });
+
+});