@Test
  public final void existingUserWithWrongPasswordCantLogIn() {

    User user = TestData.newValidUser().withPassword("wrong").build();

    LoginPage page = openLoginPage().loginExpectingError(user);

    assertThat(page.errorMessage()).isVisible();
    assertThat(page.errorMessage()).hasVisibleText("Wrong Credentials!");
  }
  @Test
  public final void nonExistingUserCantLogIn() {

    User user = TestData.newValidUser().withUsername("unknown").build();

    LoginPage page = openLoginPage().loginExpectingError(user);

    assertThat(page.errorMessage()).isVisible();
    assertThat(page.errorMessage()).hasVisibleText("Wrong Credentials!");
  }
 @Test
 public final void existingUserWithCorrectPasswordCanLogIn() {
   User user = TestData.newValidUser().build();
   WelcomePage page = openLoginPage().login(user);
   assertThat(page.headline()).hasVisibleText("Hello World!");
 }