BaseTest.java

package tests;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.chrome.ChromeOptions;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import pages.LoginPage;
import pages.ProductsPage;

import java.time.Duration;

public class BaseTest {

    WebDriver driver;
    LoginPage loginPage;
    ProductsPage productsPage;

    @BeforeMethod
    public void setup() {
        ChromeOptions options = new ChromeOptions();
        driver = new ChromeDriver(options);
        driver.manage().timeouts().implicitlyWait(Duration.ofSeconds(10));
        loginPage = new LoginPage(driver);
        productsPage = new ProductsPage(driver);
    }

    @AfterMethod(alwaysRun = true)
    public void tearDown() {
        driver.quit();
    }
}

LoginPage.java

package pages;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;

public class LoginPage {

    WebDriver driver;

    By userField = By.id("user-name");
    By passwordField = By.id("password");
    By loginButton = By.id("login-button");
    By errorMessage = By.cssSelector("[data-test=error]");

    public LoginPage(WebDriver driver) {
        this.driver = driver;
    }

    public void open() {
        driver.get("https://www.saucedemo.com/");
    }

    public void login(String user, String password) {
        driver.findElement(userField).sendKeys(user);
        driver.findElement(passwordField).sendKeys(password);
        driver.findElement(loginButton).click();
    }

    public String getErrorMessage() {
        return driver.findElement(errorMessage).getText();
    }
}

LoginTest.java

package tests;

import org.openqa.selenium.By;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.testng.Assert;
import org.testng.annotations.Test;

import static org.testng.Assert.assertEquals;

public class LoginTest extends BaseTest {

    @Test
    public void loginPositiveTest() {
        loginPage.open();
        loginPage.login("user-name", "secret_sauce");
        assertEquals(
                productsPage.getTitle(),
                "Products",
                "Логин не выполнен");
    }

    @Test
    public void checkLoginWithWrongPassword() {
        loginPage.open();
        loginPage.login("user-name", "123456");
        assertEquals(
                loginPage.getErrorMessage(),
                "Epic sadface: Username and password do not match any user in this service",
                "Сообщение об ошибке не появилось");
    }
}

ProductsPage.java

package pages;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;

public class ProductsPage {

    WebDriver driver;

    By title = By.cssSelector("[data-test=title]");

    public ProductsPage(WebDriver driver) {
        this.driver = driver;
    }

    public String getTitle() {
        return driver.findElement(title).getText();
    }
}