add unit test and improve code coverage

tests/Carousel.spec.js

@@ -1,9 +1,54 @@
 import expect from 'expect.js';
 import React from 'react';
 import ReactDOM from 'react-dom';
-import TestUtils, { Simulate } from 'react-addons-test-utils';
+import Enzyme, { mount } from 'enzyme';
+import Adapter from 'enzyme-adapter-react-15'
+import TestUtils, { Simulate } from 'react-dom/test-utils';
 import Carousel from '../src';
 
+Enzyme.configure({ adapter: new Adapter() })
+
 describe('Carousel', () => {
+    it('className prop works', () => {
+        const node = mount(<Carousel className="test-classname"/>)
+        expect(node.props().className).to.equal('test-classname')
+    })
+
+    it('prefixCls prop works', () => {
+        const node = mount(<Carousel prefixCls="test-prefix"/>)
+        expect(node.find('.test-prefix')).to.have.length(1)
+    })
+
+    it('centerDots prop works', () => {
+        const node1 = mount(<Carousel prefixCls="test-prefix" />)
+        expect(node1.find('.test-prefix-dots-centered')).to.have.length(1)
+
+        const node2 = mount(<Carousel prefixCls="test-prefix" centerDots={false}>
+        </Carousel>)
+        expect(node2.find('.test-prefix-dots-centered')).to.have.length(0)
+    })
+
+    it('largeArrowsAndDots prop works', () => {
+        const node1 = mount(<Carousel prefixCls="test-prefix"/>)
+        expect(node1.find('.test-prefix-large-mode')).to.have.length(0)
+
+        const node2 = mount(<Carousel prefixCls="test-prefix" largeArrowsAndDots/>)
+        expect(node2.find('.test-prefix-large-mode')).to.have.length(1)
+    })
+
+    it('arrows === always works', () => {
+        const node1 = mount(<Carousel prefixCls="test-prefix" arrows="test"/>)
+        expect(node1.find('.test-prefix-always-show-arrows')).to.have.length(0)
+
+        const node2 = mount(<Carousel prefixCls="test-prefix" arrows="always"/>)
+        expect(node1.find('.test-prefix-always-show-arrows')).to.have.length(0)
+    })
+
+    it('coverage improve', () => {
+        // code coverage for children.length > 0
+        mount(<Carousel>
+            <div>a</div>
+        </Carousel>)
+    })
 
 });