Dev.Pro

inventory.js

/*
Task 2: Inventory Management

Context: You are developing a simple inventory management system for a small store.
You need to create a function that takes a list of products with their names, prices, and stock levels, and returns a sorted list of products based on a given sort key (name, price, or stock) and order (ascending or descending).

Example Input:
products = [ 
{""name"": ""Product A"", ""price"": 100, ""stock"": 5}, 
{""name"": ""Product B"", ""price"": 200, ""stock"": 3}, 
{""name"": ""Product C"", ""price"": 50, ""stock"": 10}
] 
sort_key = ""price""
ascending = False

Expected Output: [
{""name"": ""Product B"", ""price"": 200, ""stock"": 3},
{""name"": ""Product A"", ""price"": 100, ""stock"": 5},
{""name"": ""Product C"", ""price"": 50, ""stock"": 10} 
]
*/

const inventory = (products, sort_key, ascending) => {
  if (ascending && sort_key != "name") {
    products.sort((a, b) => {
      return a[sort_key] - b[sort_key];
    });
  } else {
    products.sort((a, b) => {
      return b[sort_key] - a[sort_key];
    });
  }

  if (sort_key == "name") {
    products.sort((a, b) => {
      let fa = a["name"].toLowerCase();
      let fb = b["name"].toLowerCase();

      if (ascending) {
        if (fa < fb) {
          return -1;
        }
      } else {
        if (fa > fb) {
          return -1;
        }
      }
    });
  }

  return products
}

module.exports = inventory;

log_message.js

/*
Task 1: Logger

Context: Your team is working on a project where you need to log various events and errors. You are asked to create a simple logging function that writes messages to a text file with a timestamp. 

Example usage: 
log_message("application.log", "User logged in", "INFO")
log_message("application.log", "Failed login attempt", "WARNING") 

Expected Output in application.log:
[2023-04-24 12:34:56] [INFO] User logged in
[2023-04-24 12:35:10] [WARNING] Failed login attempt

RESOLUTION COMMENTS
Since was asked a simple logging funcion, I choose not to use other console methos, like console.warn() and console.error(), or severity levels specified by RFC5424.
*/

const log_message = (app, message, level) => {
  const fs = require('node:fs');

  const dateTime = new Date();

  const year = dateTime.getFullYear();
  const month = ("0" + (dateTime.getMonth() + 1)).slice(-2);
  const day = ("0" + dateTime.getDate()).slice(-2);

  const hours = dateTime.getHours();
  const minutes = dateTime.getMinutes();
  const seconds = dateTime.getSeconds();

  const logMessage = (`[${year}-${month}-${day} ${hours}:${minutes}:${seconds}] [${level}] ${message}\n`);

  try {
    fs.appendFileSync(app, logMessage);
  } catch (err) {
    console.error(err);
  }

  return logMessage;
}

module.exports = log_message;

log_message.test.js

/*
Task 1.1: Tests
Write tests scenarios for Logger

RESOLUTION COMMENTS
ATTENTION: This file MUST BE in same folder of log_message.js in order to work without any further configuration.
I decided to not use any external package for the tasks, that's why I use Math.random() as filenames and messages.
*/

const { describe, test, beforeEach } = require('node:test');
const assert = require('node:assert');
const fs = require('node:fs');
const { exec } = require("node:child_process");

const log_message = require('./log_message');

const levels = [
    'ERROR',
    'WARN',
    'INFO',
    'DEBUG'
];

let fileName;

describe('logger tests', async () => {
    beforeEach(() => {
        exec('rm *.log');
        fileName = `${Math.random()}.log`;
    });

    test("file should exists", () => {
        log_message(fileName, "User logged in", "INFO");
        const isFile = fs.existsSync(fileName);
        assert.ok(isFile);
    });

    test("log message should have the correct format", () => {
        const level = levels[
            Math.floor(Math.random() * levels.length)
        ];
        const message = Math.random().toString();

        const logMessage = log_message(fileName, message, level);
        const messageElements = logMessage.split(" ");

        const date = messageElements[0];
        const dateRegex = /^\[20\d{2}-(0[1-9]|1[1,2])-(0[1-9]|[12][0-9]|3[01])/;

        const time = messageElements[1];
        const timeRegex = /^(0?[0-9]|1[0-9]|2[0-3]):(0?[1-5]?[0-9]):(0?[1-5]?[0-9])\]$/;

        const lvl = messageElements[2];
        const lvlRegex = /^\[[A-Z]*\]$/;

        const msg = messageElements[3];
        const msgRegex = /[a-zA-Z0-9]/;

        assert.match(date, dateRegex);
        assert.match(time, timeRegex);
        assert.match(lvl, lvlRegex);
        assert.match(msg, msgRegex);
    });

    test('file should contain correct message', () => {
        const level = levels[
            Math.floor(Math.random() * levels.length)
        ];
        const message = Math.random().toString();

        const logMessage = log_message(fileName, message, level);

        const fileMessage = fs.readFileSync(fileName, 'utf8');

        assert.strictEqual(logMessage, fileMessage);
    });
});