trikitrok

// From  Ayush Jindal's exercises for code smells https://github.com/ayjindal/CodeSmells

class Customer {
  private readonly name: string;
  private readonly currentAddress: Address;

  constructor(name: string, address: Address) {
    this.name = name;
    this.currentAddress = address;
  }

trikitrok

// From Code Smells – Part II, Ana Nogal https://www.ananogal.com/blog/code-smells-part-two/

enum EmployeeType {
  Worker,
  Supervisor,
  Manager
}

class Employee {
  private readonly salary: number;

trikitrok

// Adapted from Code Smell: Null Check, Joe Eames https://medium.com/thinkster-io/code-smell-null-check-a0c4851fafbf

const DEFAULT_DISCOUNT: number = 1.0;

class DiscountCalculator {
  private customerRepository: CustomerRepository;

  constructor(customerRepository: CustomerRepository) {
    this.customerRepository = customerRepository;
  }

trikitrok

// From Fixing Object oriented abusers, Manh Phan https://ducmanhphan.github.io/2020-01-24-Fixing-object-oriented-abusers/

class CheckoutHandlder {
  // ...
  convertToCurrency(price: number, currencyTo: string): number {
    if (currencyTo === "EUR") {
      return price * 0.9;
    } else if (currencyTo === "CAD") {
      return price * 1.35;
    } else {

trikitrok

WORKING EFFECTIVELY WITH LEGACY CODE

To me, legacy code is simply code without tests. I’ve gotten some grief for this definition. What do tests have to do with whether code is bad? To me, the answer is straightforward, and it is a point that I elaborate throughout the book: Code without tests is bad code. It doesn’t matter how well written it is; it doesn’t matter how pretty or object-oriented or well-encapsulated it is. With tests, we can change the behavior of our code quickly and verifiably. Without them, we really don’t know if our code is getting better or worse.

Chapter 1 Changing Software

Four Reasons to Change Software: For simplicity’s sake, let’s look at four primary reasons to change software.

trikitrok

export class Rover {
  // some code

  execute(command) {
    if (command === 'l' || command === 'r') {
      if (this.direction === "N") {
        if (command === 'r') {
          this.direction = "E";
        } else {
          this.direction = "W";

trikitrok

import {UnusualSpendingDetector} from "../src/UnusualSpendingDetector";
import {stub} from "./PaymentsRepositoryHelper";

describe('UnusualSpendingDetector', () => {
  const currentMonth = '2020-02';
  const previousMonth = '2020-01';
  const userId = '1234';
  let paymentsRepository;
  let detector;
  let knowingThat;

trikitrok

import {when} from "jest-when";

export function stub(paymentsRepository) {
  const monthPaymentsBuilder = {
    inMonth: inMonth
  };

  return knowingThat;

  function knowingThat() {

trikitrok

import {UnusualSpendingDetector} from "../src/UnusualSpendingDetector";
import {when} from 'jest-when'

describe('UnusualSpendingDetector', () => {
  const currentMonth = '2020-02';
  const previousMonth = '2020-01';
  const userId = '1234';
  let paymentsRepository;
  let detector;

trikitrok

import {UnusualSpendingDetector} from "../src/UnusualSpendingDetector";

describe('UnusualSpendingDetector', () => {
  const currentMonth = '2020-02';
  const previousMonth = '2020-01';
  const userId = '1234';
  let paymentsRepository;
  let detector;

  beforeEach(() => {