If all you have is a hammer, everything looks like a <Nail />

decribe.js

import React, { PropTypes } from 'react'

const Describe = ({ title, children }) => (
  <div>
    <h1>{title}</h1>
    <ul>{children}</ul>
  </div>
)

Describe.propTypes = {
  title: PropTypes.string,
  children: PropTypes.oneOfType([
    PropTypes.arrayOf(PropTypes.element),
    PropTypes.element,
  ]),
}

export default Describe

it.js

import React, { Component, PropTypes } from 'react'

class It extends Component {

  constructor(props) {
    super(props)

    this.assert = this.assert.bind(this)
  }

  assert(condition) {
    return (
      <div style={{ color: condition ? 'green' : 'red' }}>
        {this.props.title} {condition ? '😻' : '😿'}
      </div>
    )
  }

  render() {
    return (
      <li>
        {this.props.children(this.assert)}
      </li>
    )
  }

}

It.propTypes = {
  title: PropTypes.string,
  children: PropTypes.func,
}

export default It

test.js

import React from 'react'
import Describe from './describe'
import It from './it'

const add = (a, b) => a + b

const Test = () => (
  <Describe title="add()">
    <It title="adds two numbers">
      {assert => assert(add(2, 3) === 5)}
    </It>
    <It title="doesn't add the third number">
      {assert => assert(add(2, 3, 5) === add(2, 3))}
    </It>
  </Describe>
)

export default Test