Number Guessing Game

import * as readline from "node:readline";
import { stdin, stdout } from "node:process";
import { randomInt } from "node:crypto";

// ask prints a prompt and waits for one line of input, pulling it from the
// readline interface's own async iterator rather than question()/promises —
// the one readline API that does not drop a line when several prompts are
// answered back-to-back, typed by hand or piped in from a file. It resolves
// to null once there is nothing left to read (stdin closed), so a loop can
// stop cleanly instead of spinning on an empty answer forever.
function makeAsk(rl: readline.Interface) {
  const it = rl[Symbol.asyncIterator]();
  return async (prompt: string): Promise<string | null> => {
    stdout.write(prompt);
    const { value, done } = await it.next();
    return done ? null : value;
  };
}

// playGame is a testable version of the game: hand it the secret number and
// a list of guesses, and it returns how many tries it took (or null if the
// secret was never guessed).
export function playGame(secret: number, guesses: number[]): number | null {
  let taken = 0;
  for (const guess of guesses) {
    taken += 1;
    if (guess === secret) {
      return taken;
    }
  }
  return null;
}

async function main(): Promise<void> {
  const rl = readline.createInterface({ input: stdin, terminal: false });
  const ask = makeAsk(rl);

  // The computer secretly picks a whole number from 1 to 100.
  const secretNumber = randomInt(1, 101);
  let guessesTaken = 0;

  console.log("I am thinking of a number between 1 and 100.");

  while (true) {
    const line = await ask("Your guess: ");
    if (line === null) {
      console.log("\nNo more input — goodbye.");
      break;
    }
    const guess = Number(line.trim());
    guessesTaken += 1;

    if (guess < secretNumber) {
      console.log("Too low. Try a bigger number.");
    } else if (guess > secretNumber) {
      console.log("Too high. Try a smaller number.");
    } else {
      console.log(`Correct! You got it in ${guessesTaken} guesses.`);
      break;
    }
  }

  rl.close();
}

if (require.main === module) {
  main();
}

import { test } from "node:test";
import assert from "node:assert/strict";
import { randomInt } from "node:crypto";
import { playGame } from "./number-guessing-game";

test("correct on the first try takes 1 guess", () => {
  assert.equal(playGame(42, [42]), 1);
});

test("correct on the third guess returns 3", () => {
  assert.equal(playGame(50, [10, 90, 50]), 3);
});

test("never guessing it returns null, not a crash", () => {
  assert.equal(playGame(7, [1, 2, 3]), null);
});

test("the secret number is always between 1 and 100", () => {
  for (let i = 0; i < 1000; i++) {
    const n = randomInt(1, 101);
    assert.ok(n >= 1 && n <= 100);
  }
});

I am thinking of a number between 1 and 100.
Your guess: 50
Too low. Try a bigger number.
Your guess: 75
Too high. Try a smaller number.
Your guess: 63
Correct! You got it in 3 guesses.

// Jenkinsfile — runs the type-checker and tests automatically every time the code changes.
pipeline {
    agent any                                  // run on any available machine

    stages {
        stage('Get the code') {
            steps { checkout scm }             // download the latest code
        }
        stage('Set up Node') {
            steps {
                sh 'node --version'                              // confirm Node is installed
                sh 'npm install -D typescript @types/node'       // zero runtime deps — just the compiler and its Node types
            }
        }
        stage('Type-check and test') {
            steps {
                sh 'npx tsc --noEmit'                 // catch type errors before anything runs
                sh 'npx tsc'                           // compile to plain JavaScript
                sh 'node --test guessing_game.test.js'            // Node's built-in test runner, no extra install needed
            }
        }
    }

    post {
        success { echo 'All tests passed.' }
        failure { echo 'A test failed — look above.' }
    }
}