fix: support .attrs method (#8)

Closes #7

Author: gregberge

packages/styled-components/src/styled.js

@@ -5,6 +5,10 @@ import { Box } from './Box'
 
 function getCreateStyle(baseCreateStyle) {
   const createStyle = (...args) => baseCreateStyle([css(...args)])
+  createStyle.attrs = attrs => {
+    const nextCreateStyle = baseCreateStyle.attrs(attrs)
+    return getCreateStyle(nextCreateStyle)
+  }
   createStyle.withConfig = config => {
     const nextCreateStyle = baseCreateStyle.withConfig(config)
     return getCreateStyle(nextCreateStyle)

packages/styled-components/src/styled.test.js

@@ -65,6 +65,14 @@ describe('#styled', () => {
     expect(container.firstChild).toHaveStyleRule('margin-top', '2px')
     expect(container.firstChild).toHaveStyleRule('padding', '4px')
   })
+  it('works with "attrs"', () => {
+    const Dummy = styled.div.attrs({ 'aria-label': 'label' })`
+      margin: 2;
+    `
+    const { container } = render(<Dummy />)
+    expect(container.firstChild.getAttribute('aria-label')).toBe('label')
+    expect(container.firstChild).toHaveStyleRule('margin', '8px')
+  })
 })
 
 describe('#styled.xxx', () => {