Tune the tests for positioning

These tests did not cover the classes that should have been
automatically applied to the dropdown based on the space around it. Now
they both test that the dropdown should be facing down, because there is
enough space below it to display the dropdown.

tests/dropdown/positioning-tests.js

@@ -58,7 +58,7 @@ test('appends to the dropdown parent', function (assert) {
     );
 });
 
-test('dropdown is positioned with static margins', function (assert) {
+test('dropdown is positioned down with static margins', function (assert) {
     var $ = require('jquery');
     var $select = $('<select></select>');
     var $parent = $('<div></div>');
@@ -100,6 +100,11 @@ test('dropdown is positioned with static margins', function (assert) {
     dropdown.position($dropdown, $container);
     dropdown._showDropdown();
 
+    assert.ok(
+        dropdown.$dropdown.hasClass('select2-dropdown--below'),
+        'The dropdown should be forced down'
+    );
+
     assert.equal(
         $dropdown.css('top').substring(0, 2),
         $container.outerHeight() + 5,
@@ -113,7 +118,7 @@ test('dropdown is positioned with static margins', function (assert) {
     );
 });
 
-test('dropdown is positioned with absolute offsets', function (assert) {
+test('dropdown is positioned down with absolute offsets', function (assert) {
     var $ = require('jquery');
     var $select = $('<select></select>');
     var $parent = $('<div></div>');
@@ -153,6 +158,11 @@ test('dropdown is positioned with absolute offsets', function (assert) {
     dropdown.position($dropdown, $container);
     dropdown._showDropdown();
 
+    assert.ok(
+        dropdown.$dropdown.hasClass('select2-dropdown--below'),
+        'The dropdown should be forced down'
+    );
+
     assert.equal(
         $dropdown.css('top').substring(0, 2),
         $container.outerHeight(),