Sawtaytoes
10/15/2018 - 7:23 AM

`getRandomIndexFromItemCount` as a Generic Base Function

We're using the previous getRandomColorSetIndex to compose over getRandomIndexFromItemCount which now acts as a unit-testable base function. This way, we can change the functionality of getRandomColorSetIndex without changing the API.

flashRandomLight.js
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const pluckRandomNumberFromRange = require('./pluckRandomNumberFromRange')

const getRandomColorSetIndex = () => (
  pluckRandomNumberFromRange(
    colorSets.length,
  )
)

const flashRandomLight = (
  observable,
) => (
  observable
  .do(console.log.bind(console, 'isHalloween:'))
  .filter(Boolean)
  .map(getRandomColorSetIndex)
  .map(getColorSetAtIndex)
  .map(doScaryLightFlash)
  .switchMap(getDataFromPromise)
)

module.exports = flashRandomLight
getRandomIndexFromItemCount.js
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const pluckRandomNumberFromRange = (
  upperBound,
  dependencies = {
    randomizer: Math.random,
  },
) => (
  Math
  .floor(
    dependencies
    .randomizer() * upperBound
  )
)

module.exports = pluckRandomNumberFromRange