message: clean up Avatar tests, add getImageURL() check
diff: import React from 'react'
  -import Avatar, {IMAGE_BASE_URL} from '../Avatar'
  +import Avatar, {IMAGE_BASE_URL, getImageURL} from '../Avatar'
  import renderer from 'react-test-renderer'
  const render = component => renderer.create(component).toJSON()
  describe('Avatar', () => {
  - const urlFor = (username, size) => `${IMAGE_BASE_URL}primer?v=3&s=${size}`
  + const urlFor = (username, size) => `${IMAGE_BASE_URL}${username}?v=3&s=${size}`
  it('renders small by default', () => {
  expect(render(<Avatar username='primer'/>))
  .toEqual(render(<img className='avatar avatar-small' src={`${IMAGE_BASE_URL}primer?v=3&s=40`} width={20} height={20} alt='primer' />))
  @@ -22,4 +22,9 @@ describe('Avatar', () => {
  expect(render(<Avatar username='primer' isChild />))
  .toEqual(render(<img className='avatar avatar-small avatar-child' src={urlFor('primer', 40)} width={20} height={20} alt='primer' />))
  })
  +
  + it('exports getImageURL() and supports src prop', () => {
  + expect(render(<Avatar username='primer' src={getImageURL('primer', {v: 4, size: 100})} />))
  + .toEqual(render(<img className='avatar avatar-small' src={`${IMAGE_BASE_URL}primer?v=4&size=100`} width={20} height={20} alt='primer' />))
  + })
  })
  