add CardCloseButton tests

__tests__/components/CardCloseButton.test.jsx

@@ -0,0 +1,23 @@
+import React from 'react';
+import { mountWithContexts } from '../enzymeHelpers';
+import CardCloseButton from '../../src/components/CardCloseButton';
+
+describe('<CardCloseButton>', () => {
+  test('should render close button', () => {
+    const wrapper = mountWithContexts(<CardCloseButton />);
+    const button = wrapper.find('Button');
+    expect(button).toHaveLength(1);
+    expect(button.prop('variant')).toBe('plain');
+    expect(button.prop('className')).toBe('pf-c-card__close');
+    expect(wrapper.find('Link')).toHaveLength(0);
+  });
+
+  test('should render close link when `linkTo` prop provided', () => {
+    const wrapper = mountWithContexts(<CardCloseButton linkTo="/foo" />);
+    expect(wrapper.find('Button')).toHaveLength(0);
+    const link = wrapper.find('Link');
+    expect(link).toHaveLength(1);
+    expect(link.prop('to')).toEqual('/foo');
+    expect(link.prop('className')).toEqual('pf-c-button pf-c-card__close');
+  });
+});