testing.js

import _ from "underscore"
import game from "./sequentialActions.js"

function testInterpreter (program, inputs, accOutputs) {
  switch (program.action) {
    case "read":
      const input = inputs[0]
      const rest = inputs.slice(1)
      return testInterpreter(program.next(input), rest, accOutputs)

    case "print":
      return testInterpreter(
        program.next(),
        inputs,
        accOutputs.concat(program.string)
      )

    case "pure":
      return accOutputs
  }
}

const outputs = testInterpreter(game, ["3", "90", "32", "42"], [])
const expectedOutputs = [
  "Enter a guess",
  "Higher",
  "Enter a guess",
  "Lower",
  "Enter a guess",
  "Higher",
  "Enter a guess",
  "Congratulations! You found it."
]

if (_.isEqual(outputs, expectedOutputs)) {
  console.log("All is well")
} else {
  console.log("Test failure", outputs, expectedOutputs)
}