JavaScript ???? ??? ???? ???? ???? ????? ??? ??? ?????. ????? ?? ???? ??? ??? ???? ??? ??? ??? ? ?? ?? ??? ??????? ???? ??? ????? ??? ??????. ? ???? ?? ??? ??? ??? 5?? ?? JavaScript ??? ??? ???????.

?? ???? ??? ??? ??? ??? ?????. ???? ?? ??, ??? ? ?? ??? ????? ????? ???? ????? ???? ??? ?????. ?? ?? ???? ???? ???? ?? ?? ?? JavaScript ??? ?????? Jest? ?? ?????. ??? Jest? ??? ??? ?? ???? ????.

function add(a, b) {
  return a + b;
}

test('add function correctly adds two numbers', () => {
  expect(add(2, 3)).toBe(5);
  expect(add(-1, 1)).toBe(0);
  expect(add(0, 0)).toBe(0);
});

? ???? ??? ??? ?? ??? ??? ????? ???? ?? ?? ?? ??? ????? ????. ??? ?? ???? ?? ?? ??? ??? ???? ?? ?? ??? ?????? ? ??? ???.

?? ??? ?? ?? ???? ??????? ??? ??? ??? ?? ????? ?????. ? ??? ?? ??? ???? ?? ???? ???? ?? ?? ?? ???? ???? ?????. ?? ??, ??? ?? ??? ?????? ??? ??? ??? ????? ???? ? ????. ??? Jest? ?? ??????? ??? ?? ???? ????.

const UserAuth = require('./userAuth');
const mockDatabase = require('./mockDatabase');

jest.mock('./database', () => mockDatabase);

describe('User Authentication', () => {
  test('successfully authenticates a valid user', async () => {
    const userAuth = new UserAuth();
    const result = await userAuth.authenticate('validuser', 'correctpassword');
    expect(result).toBe(true);
  });

  test('fails to authenticate an invalid user', async () => {
    const userAuth = new UserAuth();
    const result = await userAuth.authenticate('invaliduser', 'wrongpassword');
    expect(result).toBe(false);
  });
});

? ?? ?????? UserAuth ??? ??????? ???? ?????? ???? ????? ???? ????. ?? ??????? ???? ??? ??? ???? ??? ?? ?? ?? ??? ??? ? ????.

?? ? ??(E2E) ???? ??????? ?? ??? ?? ??? ??????? ???? ?? ??? ????. ? ??? ???? ?? ??? ?? ??? ?? ???? ? ?? ??? ???? ? ??? ???. ?? ??? ???? ??? E2E ??? ?????? Cypress? ?? ?????. ??? ??? ??? ?? Cypress ???? ????.

describe('Login Form', () => {
  it('successfully logs in a user', () => {
    cy.visit('/login');
    cy.get('input[name="username"]').type('testuser');
    cy.get('input[name="password"]').type('testpassword');
    cy.get('button[type="submit"]').click();
    cy.url().should('include', '/dashboard');
    cy.contains('Welcome, Test User').should('be.visible');
  });
});

? E2E ???? ??? ???? ????, ?? ??? ????, ??? ????, ???? ????? ????? ????? ??????? ???? ????? ??????. ??? ???? ??? ???? ??????? ???? ????? ???? ? ?? ?????.

??? ???? ??? ?? ??? ???? ?? ???? ??? ???? ?? ?? ?? ???? ?????. ? ?? ??? API, ?????? ?? ?? ??? ???? ??? ? ?? ?????. ??? Jest? ???? API ??? ???? ????.

function add(a, b) {
  return a + b;
}

test('add function correctly adds two numbers', () => {
  expect(add(2, 3)).toBe(5);
  expect(add(-1, 1)).toBe(0);
  expect(add(0, 0)).toBe(0);
});

? ???? ?? API ??? ???? ?? ?? ??? ??? ??? ???? ?? axios ?????? ?????. ?? ?? ?? API? ????? ??? ???? ?? fetchUserData ??? ??? ???? ? ????.

?? ?? ??? ????? ?????? ??? ????? ???? ? ??? ?? ???????. 100% ??? ?? ?? ??? ????? ??? ?? ???? ??? ? ?? ??? ???? ??? ?????. ?? ???? ???? ???? ?? Jest? ? ???? ?? ???? ??? Istanbul? ?????. ????? ????? Jest? ???? ??? ??? ????.

const UserAuth = require('./userAuth');
const mockDatabase = require('./mockDatabase');

jest.mock('./database', () => mockDatabase);

describe('User Authentication', () => {
  test('successfully authenticates a valid user', async () => {
    const userAuth = new UserAuth();
    const result = await userAuth.authenticate('validuser', 'correctpassword');
    expect(result).toBe(true);
  });

  test('fails to authenticate an invalid user', async () => {
    const userAuth = new UserAuth();
    const result = await userAuth.authenticate('invaliduser', 'wrongpassword');
    expect(result).toBe(false);
  });
});

? ??? Jest?? ?? ?? ??? ????, ??? ? lcov ???? ???? ????, ??? ?? ??? ?? ?? ?? ?? ??? 80%? ????? ?????.

??? ??? ??? ?????? JavaScript ??????? ??? ???? ?? ???????. ??? ???? ???? ?????? ?? ???? ?? ?????. ?????? ???? ?? ???? ???? ???. ??? ?? ??? ????? ???? ?????? ??? ?? ??? ????? ??? ? ????.

?? ?? ????? ???? ?? ? ??? ??? ?? ??(TDD)???. TDD? ???? ?? ??? ???? ?? ???? ?????. ? ?? ??? ?? ??? ???? ??, ?? ??? ????, ?? ??? ?? ???? ??? ???? ? ??? ???. ??? TDD? ???? ??? ??? ??? ???? ??? ?? ????.

describe('Login Form', () => {
  it('successfully logs in a user', () => {
    cy.visit('/login');
    cy.get('input[name="username"]').type('testuser');
    cy.get('input[name="password"]').type('testpassword');
    cy.get('button[type="submit"]').click();
    cy.url().should('include', '/dashboard');
    cy.contains('Welcome, Test User').should('be.visible');
  });
});

? TDD ???? ?? 0?? ???? ?? ???? ??? ???? ? ??? ??? ?? ???? ?????. ?? ?? ??? ???? ???? ?? Calculator ???? ?????. ? ?? ??? ???? ??? ??? ?? ??? ???? ???? ???? ??? ??? ?? ? ????.

JavaScript ???? ? ?? ??? ??? ??? ??? ???? ????. API ???? ?????? ??? ?? JavaScript? ?? ??? ???????. Jest? ??? ??? ????? ????? ?? ?? ??? ?????. ??? ??? ??? ????? ????.

const axios = require('axios');
jest.mock('axios');

const fetchUserData = async (userId) => {
  const response = await axios.get(`https://api.example.com/users/${userId}`);
  return response.data;
};

test('fetchUserData retrieves user information', async () => {
  const mockUser = { id: 1, name: 'John Doe', email: 'john@example.com' };
  axios.get.mockResolvedValue({ data: mockUser });

  const userData = await fetchUserData(1);
  expect(userData).toEqual(mockUser);
  expect(axios.get).toHaveBeenCalledWith('https://api.example.com/users/1');
});

? ?????? async ??? wait ???? ???? ??? fetchData ??? ?????. Jest? ???? ???? ?? Promise? ??? ??? ???? ?????.

??????? ????? ?? ?? ??? ??? ?? ????? ???? ?? ??? ????? ?? ??? ????. React ??????? ?? ???? ?? ???? ??? ??? ???? ?? ??? ?????? ???? React ??? ?????? ?????. ??? ??? ??? ????? ????? ????.

function add(a, b) {
  return a + b;
}

test('add function correctly adds two numbers', () => {
  expect(add(2, 3)).toBe(5);
  expect(add(-1, 1)).toBe(0);
  expect(add(0, 0)).toBe(0);
});

? ?????? ??? ?? ??? ?????, ??? ???? ??? ?? ??? ???????, ??? ??? ???? ????? ?????.

?? ???? JavaScript ??????? ???? ????? ?? ? ?? ??? ?????. ????? ? ?? ???? ?? ?? ??? ??? ?? ???? ???? ?? ?? ??? ?? ???? ??? ?? ??? ??? ?? ? ????. ??? Benchmark.js ?????? ???? ??? ?? ?? ????? ??? ???? ????.

const UserAuth = require('./userAuth');
const mockDatabase = require('./mockDatabase');

jest.mock('./database', () => mockDatabase);

describe('User Authentication', () => {
  test('successfully authenticates a valid user', async () => {
    const userAuth = new UserAuth();
    const result = await userAuth.authenticate('validuser', 'correctpassword');
    expect(result).toBe(true);
  });

  test('fails to authenticate an invalid user', async () => {
    const userAuth = new UserAuth();
    const result = await userAuth.authenticate('invaliduser', 'wrongpassword');
    expect(result).toBe(false);
  });
});

? ?? ???? ?? ??? ? ?? ????? ?? ??? ???? ??????? ?? ????? ???? ??? ??? ??? ? ??? ???.

?? ??? ??????? ???? ?? ??? ???? ??? ???? ??? ??? ????? ????? ?? ??? ????. ?? ?? ???? ???? ?? ??? ??? ???? ???, ???? ??? ??? ?? ??? ???? ? ??? ???. Fast-check? JavaScript? ?? ?? ???? ?? ???? ????????. ?? ??? ????.

describe('Login Form', () => {
  it('successfully logs in a user', () => {
    cy.visit('/login');
    cy.get('input[name="username"]').type('testuser');
    cy.get('input[name="password"]').type('testpassword');
    cy.get('button[type="submit"]').click();
    cy.url().should('include', '/dashboard');
    cy.contains('Welcome, Test User').should('be.visible');
  });
});

? ????? fast-check? ??? ??? ???? abs ??? ?? ??? ?? ???? ????? ?????.

??? ???? ???? ?? ?? ????? ?? ??? ? ??? ???? ?? ?????. ?? ????? ???? ? ?? ??? ?? ??? ???? ?? ???? ????? beforeEach ? afterEach ??? ???? ??? ??? ?? ? ???? ????. ? ?? ??? ???? ???? ???? ??? ????. ?? ??? ????.

const axios = require('axios');
jest.mock('axios');

const fetchUserData = async (userId) => {
  const response = await axios.get(`https://api.example.com/users/${userId}`);
  return response.data;
};

test('fetchUserData retrieves user information', async () => {
  const mockUser = { id: 1, name: 'John Doe', email: 'john@example.com' };
  axios.get.mockResolvedValue({ data: mockUser });

  const userData = await fetchUserData(1);
  expect(userData).toEqual(mockUser);
  expect(axios.get).toHaveBeenCalledWith('https://api.example.com/users/1');
});

? ???? ?? ??? ???? ??????? ???? ?? ???? ? ?? ?? ? ?? ?? ????? ? ????.

????? ??? JavaScript ??? ??? ?????? ??? ??? ???? ?? ???????. ?? ??? ???? ?? ????? ??? ?? ??? ??????? ????? ????? ? ??? ??? ??????? ??? ? ??? ??? ???. ??, ?? ?? ?? ?? ? ?? ?? ???? ?? ?? ??? ?????? ???? ??? ????? ???? ?? ??? ? ????. ???? ???? ?????? ?? ???? ???? ?????? ?? ??????. ??? ??? ???? ???? ??? ?? ??? ??? ?????? ?? ????? ?? ??? ???? ???? JavaScript ??????? ??? ? ????.

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