Added initial tests for wheel service [ci skip]

Author: Joel Mukuthu

test/spec/services/wheel.js

@@ -0,0 +1,46 @@
+'use strict';
+
+describe('Service: wheel', function () {
+  var element;
+
+  beforeEach(module('snapscroll'));
+
+  beforeEach(function () {
+    var html = [
+          '<div style="height: 100px; overflow: auto">',
+            '<div style="height: 1000px"></div>',
+          '</div>'
+        ].join('');
+    element = angular.element(html);
+    angular.element(document).find('body').append(element);
+  });
+
+  afterEach(function () {
+    angular.element(document).find('body').empty();
+  });
+
+  it('provides a \'bind\' function and an \'unbind\' function', inject(function (wheel) {
+    expect(angular.isFunction(wheel.bind)).toBe(true);
+    expect(angular.isFunction(wheel.unbind)).toBe(true);
+  }));
+
+  describe('.bind', function () {
+    var wheel;
+
+    beforeEach(inject(function (_wheel_) {
+      wheel = _wheel_;
+    }));
+
+    it('throws an error if up() and down() callbacks are not provided', function () {
+      expect(function () {
+          wheel.bind(element, {});
+      }).toThrowError('No callbacks provided');
+    });
+
+    it('prevents the default wheel event in one direction if a callback for the same direction is provided', function () {
+    });
+
+    it('does not prevents the default wheel event in one direction if a callback for that direction is not provided', function () {
+    });
+  });
+});