Reversing a string

reverseString.js

const Iso = (to, from) => ({ to, from })
const string = Iso(cs => cs.join(""), str => [...str])

const reverse = xs => xs.reverse()
const pipe = (...fns) => x => fns.reduce((acc, fn) => fn(acc), x)

// Reverses a string
const reverseString = pipe(
  string.from,
  reverse,
  string.to
)

// Tests

const assert = require("assert")

const runTests = f => cases => {
  cases.forEach(([input, output]) =>
    assert(f(input) === output, `Expected: ${output}, Actual: ${f(input)}`)
  )
  console.log("All tests passed!")
}

const cases = [
  ["hello world", "dlrow olleh"],
  ["asdf", "fdsa"],
  ["CS rocks!", "!skcor SC"]
]

runTests(reverseString)(cases)