Refactor stage spec

Stage spec was not working
and never has been. Re worked
the spec and changed a class in
the component.

app/assets/javascripts/pipelines/components/stage.vue

@@ -137,7 +137,7 @@ export default {
     },
 
     isDropdownOpen() {
-      return this.$el.classList.contains('open');
+      return this.$el.classList.contains('show');
     },
 
     pipelineActionRequestComplete() {

spec/frontend/pipelines/stage_spec.js

@@ -81,10 +81,15 @@ describe('Pipelines stage component', () => {
     });
 
     it('should close the dropdown', () => {
-      wrapper.trigger('click');
+      wrapper.setMethods({
+        closeDropdown: jest.fn(),
+        isDropdownOpen: jest.fn().mockReturnValue(false),
+      });
+
+      wrapper.find('button').trigger('click');
 
       return waitForPromises().then(() => {
-        expect(wrapper.classes('open')).toBe(false);
+        expect(wrapper.vm.closeDropdown).toHaveBeenCalled();
       });
     });
   });