Fingerprint methods of an object

Rectangle.test.js

import React from 'react'
import { shallow } from 'enzyme'

import { RectangleBase as Rectangle } from '.'

const defaultProps = {
  width: 10,
  height: 10,
  x: 1,
  y: 1
}

const fingerprint = (trackFns = []) => {
  const log = []

  const spy = fn => (...args) => {
    log.push({ fn, args })
  }

  return {
    mocks: trackFns.reduce(
      (tracker, key) => ({ ...tracker, [key]: spy(key) }),
      {}
    ),
    log
  }
}

describe('Rectangle', () => {
  describe('radius', () => {
    describe('when it has no radius', () => {
      it('calls fillRect on ctx with proper values', () => {
        const ctx = fingerprint([
          'beginPath',
          'moveTo',
          'lineTo',
          'stroke',
          'closePath'
        ])
        shallow(<Rectangle {...defaultProps} ctx={ctx.mocks} />)
        expect(ctx.log).toMatchSnapshot()
      })
    })
  })
})