Selenium Waits & Expected Conditions

@Test
void noWaitFails() {
  Bookshelf.submitReview(driver, "Saved a moment later, after the delay.");
  // The review is only "saved" after the server answers (about one second), so this fails.
  assertThrows(org.openqa.selenium.NoSuchElementException.class,
      () -> driver.findElement(Bookshelf.SAVED_REVIEW));
}

def test_no_wait_fails(driver, submit_review):
    submit_review()
    # The review is only "saved" after the server answers (about one second).
    with pytest.raises(NoSuchElementException):
        driver.find_element(*SAVED_REVIEW)

@Test
void timeoutMessage() {
  driver.get(Bookshelf.BASE_URL + "/books/3");
  WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(1));
  TimeoutException e = assertThrows(TimeoutException.class,
      () -> wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("does-not-exist"))));
  System.out.println("TIMEOUT MESSAGE: " + e.getMessage().lines().findFirst().orElse(""));
}

def test_timeout_message(driver, base_url):
    driver.get(f"{base_url}/books/3")
    with pytest.raises(TimeoutException) as info:
        WebDriverWait(driver, 1).until(EC.visibility_of_element_located((By.ID, "does-not-exist")), message="no such box")
    print("TIMEOUT MESSAGE:", str(info.value).splitlines()[0])

TIMEOUT MESSAGE: Expected condition failed: waiting for visibility of element found by By.id: does-not-exist, but... org.openqa.selenium.NoSuchElementException: no such element: Unable to locate element: {"method":"css selector","selector":"#does\-not\-exist"}.
TIMEOUT MESSAGE: Message: no such box

@Test
void customExpectedCondition() {
  Bookshelf.submitReview(driver, "Saved a moment later, after the delay.");
  // An ExpectedCondition is a java.util.function.Function<WebDriver, T>: a lambda is enough.
  ExpectedCondition<Integer> savedReviewCount = d -> {
    var saved = d.findElements(Bookshelf.SAVED_REVIEW);
    return saved.isEmpty() ? null : saved.size();
  };
  Integer count = new WebDriverWait(driver, Duration.ofSeconds(5)).until(savedReviewCount);
  assertEquals(1, count);
  // Any JDK Function works too, without Guava on the type.
  Function<WebDriver, WebElement> asFunction = ExpectedConditions.presenceOfElementLocated(Bookshelf.SAVED_REVIEW);
  assertNotNull(asFunction.apply(driver));
}

public interface ExpectedCondition<T extends @Nullable Object>
    extends java.util.function.Function<WebDriver, T> {}

// Before: compiled with 4.50 and earlier, fails with 4.51
com.google.common.base.Function<WebDriver, WebElement> condition =
    ExpectedConditions.elementToBeClickable(By.id("submit"));

// After: a drop-in replacement, the apply method is identical
java.util.function.Function<WebDriver, WebElement> condition =
    ExpectedConditions.elementToBeClickable(By.id("submit"));

Check.java:7: error: incompatible types: ExpectedCondition<WebElement> cannot be converted to Function<WebDriver,WebElement>
        ExpectedConditions.elementToBeClickable(By.id("submit"));

public static class RecordingListener implements WebDriverListener {
  final List<String> events = new ArrayList<>();

  @Override public void beforeGet(WebDriver driver, String url) { events.add("before get " + url); }
  @Override public void afterGet(WebDriver driver, String url) { events.add("after get"); }
  @Override public void beforeClick(WebElement element) { events.add("before click " + element.getDomAttribute("data-testid")); }
  @Override public void afterSendKeys(WebElement element, CharSequence... keys) { events.add("sent keys to " + element.getDomAttribute("id")); }
  @Override public void onError(Object target, Method method, Object[] args, InvocationTargetException e) {
    events.add("error in " + method.getName() + ": " + e.getTargetException().getClass().getSimpleName());
  }
}

@Test
void eventFiringDecorator() {
  RecordingListener listener = new RecordingListener();
  WebDriver driver = new EventFiringDecorator<WebDriver>(listener).decorate(Bookshelf.newDriver());
  try {
    driver.get(Bookshelf.BASE_URL + "/books");
    driver.findElement(By.cssSelector("[data-testid=search-input]")).sendKeys("quiet");
    driver.findElement(By.cssSelector("[data-testid=search-submit]")).click();
    assertThrows(NoSuchElementException.class, () -> driver.findElement(By.id("missing")));
    listener.events.forEach(e -> System.out.println("EVENT: " + e));
    assertTrue(listener.events.contains("before click search-submit"));
  } finally {
    driver.quit();
  }
}

EVENT: before get http://localhost:3914/books
EVENT: after get
EVENT: sent keys to q
EVENT: before click search-submit
EVENT: error in findElement: NoSuchElementException

class RecordingListener(AbstractEventListener):
    def __init__(self):
        self.events = []

    def before_navigate_to(self, url, driver):
        self.events.append(f"before navigate {url}")

    def after_navigate_to(self, url, driver):
        self.events.append("after navigate")

    def before_click(self, element, driver):
        self.events.append(f"before click {element.get_dom_attribute('data-testid')}")

    def after_change_value_of(self, element, driver):
        self.events.append(f"changed value of {element.get_dom_attribute('id')}")

    def on_exception(self, exception, driver):
        self.events.append(f"error: {type(exception).__name__}")


def test_event_firing_webdriver(driver, base_url):
    listener = RecordingListener()
    wrapped = EventFiringWebDriver(driver, listener)
    wrapped.get(f"{base_url}/books")
    wrapped.find_element(By.CSS_SELECTOR, "[data-testid=search-input]").send_keys("quiet")
    wrapped.find_element(By.CSS_SELECTOR, "[data-testid=search-submit]").click()
    with pytest.raises(NoSuchElementException):
        wrapped.find_element(By.ID, "missing")
    assert "before click search-submit" in listener.events

EVENT: before navigate http://localhost:3914/books
EVENT: after navigate
EVENT: changed value of q
EVENT: before click search-submit
EVENT: error: NoSuchElementException

@Test
void commonErrors() {
  driver.get(Bookshelf.BASE_URL + "/books/3");
  // NoSuchElementException: wrong place or wrong time.
  assertThrows(NoSuchElementException.class, () -> driver.findElement(By.id("nope")));
  // InvalidSelectorException: an XPath expression given to a CSS strategy.
  assertThrows(InvalidSelectorException.class, () -> driver.findElement(By.cssSelector("//h1")));
  // ElementNotInteractableException: the sign-in error message is in the DOM but
  // hidden until a sign-in fails.
  driver.get(Bookshelf.BASE_URL + "/signin");
  WebElement hidden = driver.findElement(By.cssSelector("[data-testid=signin-error]"));
  assertThrows(ElementNotInteractableException.class, () -> hidden.sendKeys("text"));
  // StaleElementReferenceException: the page changed after the element was found.
  WebElement username = driver.findElement(By.id("username"));
  driver.navigate().refresh();
  assertThrows(StaleElementReferenceException.class, username::getText);
  // TimeoutException is raised by the wait, not by the driver.
  assertThrows(TimeoutException.class, () -> new WebDriverWait(driver, Duration.ofMillis(500))
      .until(ExpectedConditions.visibilityOfElementLocated(By.id("nope"))));
}

def test_common_errors(driver, base_url):
    driver.get(f"{base_url}/books/3")
    with pytest.raises(NoSuchElementException):
        driver.find_element(By.ID, "nope")
    with pytest.raises(InvalidSelectorException):
        driver.find_element(By.CSS_SELECTOR, "//h1")
    driver.get(f"{base_url}/signin")
    hidden = driver.find_element(By.CSS_SELECTOR, "[data-testid=signin-error]")
    with pytest.raises(ElementNotInteractableException):
        hidden.send_keys("text")

ChromeDriverService service = new ChromeDriverService.Builder()
    .usingDriverExecutable(new File("/path/to/chromedriver"))
    .build();
WebDriver driver = new ChromeDriver(service, new ChromeOptions());

service = webdriver.ChromeService(executable_path="/path/to/chromedriver")
driver = webdriver.Chrome(service=service)

@Test
void loggingToAFile() throws Exception {
  Path output = Files.createTempFile("selenium", ".log");
  Logger root = Logger.getLogger("");
  Level previous = root.getLevel();
  root.setLevel(Level.FINE);
  for (Handler h : root.getHandlers()) h.setLevel(Level.FINE);
  Handler handler = new FileHandler(output.toString());
  handler.setFormatter(new java.util.logging.SimpleFormatter());
  root.addHandler(handler);
  Logger.getLogger(RemoteWebDriver.class.getName()).setLevel(Level.FINEST);
  try {
    driver.get(Bookshelf.BASE_URL);
    Logger.getLogger("demo").info("this is useful information");
    Logger.getLogger("demo").fine("this is detailed debug information");
  } finally {
    root.removeHandler(handler);
    handler.close();
    root.setLevel(previous);
    for (Handler h : root.getHandlers()) h.setLevel(Level.INFO);
  }
  assertTrue(Files.readString(output).contains("this is detailed debug information"));
}

Oct 25, 2026 9:44:00 PM org.openqa.selenium.remote.RemoteWebDriver log
FINE: Executing: get [d4977c173d8ebcc765e667bd34802b5c, get {url=http://localhost:3914}]
FINE: Executing request: (POST) /session/d4977c173d8ebcc765e667bd34802b5c/url {
Oct 25, 2026 9:44:01 PM org.openqa.selenium.remote.RemoteWebDriver log
INFO: this is useful information
FINE: this is detailed debug information

def test_logging_to_a_file(driver, base_url, tmp_path):
    log_path = tmp_path / "selenium.log"
    logger = logging.getLogger("selenium")
    logger.setLevel(logging.DEBUG)
    handler = logging.FileHandler(log_path)
    handler.setFormatter(logging.Formatter("%(levelname)s %(name)s: %(message)s"))
    logger.addHandler(handler)
    logging.getLogger("selenium.webdriver.remote").setLevel(logging.DEBUG)
    try:
        driver.get(base_url)
        logger.info("this is useful information")
        logger.debug("this is detailed debug information")
    finally:
        logger.removeHandler(handler)
        handler.close()
    lines = log_path.read_text().splitlines()
    assert any("this is detailed debug information" in line for line in lines)

DEBUG selenium.webdriver.remote.remote_connection: POST http://localhost:64299/session/d15d1016eade3072f6f8fe3cc0e523c5/url {'url': 'http://localhost:...
DEBUG selenium.webdriver.remote.remote_connection: Remote response: status=200 | data={"value":null} | headers=HTTPHeaderDict({'Content-Length': '14', ...
DEBUG selenium.webdriver.remote.remote_connection: Finished Request
INFO selenium: this is useful information
DEBUG selenium: this is detailed debug information