ST - Selenium - 4 - Synchronization
Synchronization in Selenium
1.
What
is Synchronization in Selenium ?
Synchronization in Selenium refers to the process of
coordinating the execution of a test script with the behavior of the web
application being tested. Since web applications are dynamic in nature and can
take varying amounts of time to load or respond, it is important to ensure that
the test script is synchronized with the web application's behavior to avoid
errors or unexpected behavior.
Synchronization in Selenium typically involves the use of
wait commands to pause the execution of the test script until a certain
condition is met. For example, you might use a wait command to wait until a
specific element appears on the page before interacting with it, or to wait for
a page to finish loading before proceeding to the next step in the test script.
Synchronization is an important aspect of Selenium testing, as it helps to
ensure that the test script is executing in a predictable and reliable manner,
regardless of the behavior of the web application being tested.
There are two main types of synchronization in Selenium:
Implicit synchronization: This is the default
synchronization method in Selenium and involves setting a timeout value that
applies to all WebDriver commands. This means that if a command takes longer
than the timeout value to execute, Selenium will automatically wait for the
command to complete before proceeding to the next command.
Explicit synchronization: This involves using wait
commands to explicitly wait for a specific condition to be met before
proceeding to the next command. This is often necessary when dealing with
dynamic web applications that may take longer to respond or load certain
elements.
2.
Please
explain “wait” keyword in Selenium ?
In Selenium, wait is a command that allows you to pause
the execution of your test script for a specified amount of time, or until a
certain condition is met. This can be useful for ensuring that the test script
is synchronized with the behavior of the web application being tested. Here's
an example of how wait can be used in Selenium to wait for an element to become
visible on the page before interacting with it:
import
org.openqa.selenium.By;
import
org.openqa.selenium.WebDriver;
import
org.openqa.selenium.WebElement;
import
org.openqa.selenium.chrome.ChromeDriver;
import
org.openqa.selenium.support.ui.ExpectedConditions;
import
org.openqa.selenium.support.ui.WebDriverWait;
public class ExampleTest {
public static void main(String[] args) {
// Set the path to the chromedriver
executable
System.setProperty("webdriver.chrome.driver",
"/path/to/chromedriver");
// Create a new ChromeDriver instance
WebDriver driver = new ChromeDriver();
// Navigate to the website
driver.get("https://www.example.com");
// Find the search box element
WebElement searchBox =
driver.findElement(By.name("q"));
// Wait for the search box to become
visible
WebDriverWait wait = new
WebDriverWait(driver, 10);
wait.until(ExpectedConditions.visibilityOf(searchBox));
// Enter a search query and submit the
form
searchBox.sendKeys("Selenium");
searchBox.submit();
// Close the browser
driver.quit();
}
}
In this example, we use the WebDriverWait class to create
a new wait object with a timeout of 10 seconds. We then use the until method of
the wait object to wait until the search box element is visible on the page
before proceeding to the next step in the test script. If the search box
element becomes visible within the specified timeout period, the test script
will proceed to the next step and enter a search query. If the element does not
become visible within the timeout period, the test script will throw a
TimeoutException. This ensures that the test script is synchronized with the
behavior of the web application and avoids errors or unexpected behavior caused
by trying to interact with an element that is not yet visible on the page.
3.
Please
explain "Implicit wait " in Selenium with a real time scenario and
corresponding code
In Selenium, implicit wait is a type of synchronization
method that applies a timeout period to all WebDriver commands. This means that
if a command takes longer than the timeout period to execute, Selenium will
automatically wait for the command to complete before proceeding to the next
command. Here's an example of how
implicit wait can be used in Selenium to wait for an element to become visible
on the page before interacting with it:
import
org.openqa.selenium.By;
import
org.openqa.selenium.WebDriver;
import
org.openqa.selenium.WebElement;
import
org.openqa.selenium.chrome.ChromeDriver;
import java.util.concurrent.TimeUnit;
public class ExampleTest {
public static void main(String[] args) {
// Set the path to the chromedriver
executable
System.setProperty("webdriver.chrome.driver",
"/path/to/chromedriver");
// Create a new ChromeDriver instance
with an implicit wait of 10 seconds
WebDriver driver = new ChromeDriver();
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
// Navigate to the website
driver.get("https://www.example.com");
// Find the search box element
WebElement searchBox =
driver.findElement(By.name("q"));
// Enter a search query and submit the
form
searchBox.sendKeys("Selenium");
searchBox.submit();
// Close the browser
driver.quit();
}
}
In this example, we use the implicitlyWait method of the
WebDriver interface to set an implicit wait period of 10 seconds for all
WebDriver commands. This means that if any command takes longer than 10 seconds
to execute, Selenium will automatically wait for the command to complete before
proceeding to the next command. If the search box element becomes visible
within the implicit wait period, the test script will proceed to the next step
and enter a search query. If the element does not become visible within the
implicit wait period, the test script will throw a NoSuchElementException. This
ensures that the test script is synchronized with the behavior of the web
application, and avoids errors or unexpected behavior caused by trying to
interact with an element that is not yet visible on the page. It's important to
note that implicit wait is not suitable for all synchronization scenarios, as
it can add unnecessary delay to the test script and may not be precise enough
for some timing-sensitive operations. In those cases, explicit waits using the
WebDriverWait class may be more appropriate.
4. Please explain "Explicit wait " in Selenium
explicit wait is a type of synchronization method that
waits for a specific condition to be met before proceeding to the next command.
Unlike implicit wait, explicit wait applies only to a specific element or condition
and allows more fine-grained control over the wait period. Here's an example of
how explicit wait can be used in Selenium to wait for an element to become
visible on the page before interacting with it:
import
org.openqa.selenium.By;
import
org.openqa.selenium.WebDriver;
import
org.openqa.selenium.WebElement;
import
org.openqa.selenium.chrome.ChromeDriver;
import
org.openqa.selenium.support.ui.WebDriverWait;
import
org.openqa.selenium.support.ui.ExpectedConditions;
public class ExampleTest {
public static void main(String[] args) {
// Set the path to the chromedriver
executable
System.setProperty("webdriver.chrome.driver",
"/path/to/chromedriver");
// Create a new ChromeDriver instance
WebDriver driver = new ChromeDriver();
// Navigate to the website
driver.get("https://www.example.com");
// Create a WebDriverWait instance with
a timeout of 10 seconds
WebDriverWait wait = new WebDriverWait(driver,
10);
// Wait for the search box element to
become visible
WebElement searchBox =
wait.until(ExpectedConditions.visibilityOfElementLocated(By.name("q")));
// Enter a search query and submit the
form
searchBox.sendKeys("Selenium");
searchBox.submit();
// Close the browser
driver.quit();
}
}
In this example, we use the WebDriverWait class to create
an explicit wait period for the search box element. The until method of the
WebDriverWait class waits for the specified condition to be met, in this case
the visibility of the search box element located by its name attribute. If the
element becomes visible within the specified timeout period of 10 seconds, the
until method returns the element, and the test script proceeds to the next step
of entering a search query. If the element does not become visible within the
timeout period, the until method throws a TimeoutException.
Using explicit wait allows us to control the wait period
more precisely, and to wait for a specific condition to be met before
proceeding to the next step of the test script. This helps to ensure that the
test script is synchronized with the behavior of the web application and avoids
errors or unexpected behavior caused by trying to interact with an element that
is not yet visible on the page.
5.
Please
explain "Fluent wait " in Selenium?
Fluent wait is another type of synchronization method in
Selenium that allows us to wait for a specific condition to be met before
proceeding to the next command. It is like explicit wait, but instead of
waiting for a single condition to be met, it allows us to wait for multiple
conditions to be met in a fluent and flexible way. Here's an example of how
fluent wait can be used in Selenium to wait for an element to become visible
and clickable on the page before interacting with it:
import org.openqa.selenium.By;
import
org.openqa.selenium.WebDriver;
import
org.openqa.selenium.WebElement;
import
org.openqa.selenium.chrome.ChromeDriver;
import
org.openqa.selenium.support.ui.WebDriverWait;
import
org.openqa.selenium.support.ui.FluentWait;
import org.openqa.selenium.support.ui.ExpectedConditions;
import java.time.Duration;
public class ExampleTest {
public static void main(String[] args) {
// Set the path to the chromedriver
executable
System.setProperty("webdriver.chrome.driver",
"/path/to/chromedriver");
// Create a new ChromeDriver instance
WebDriver driver = new ChromeDriver();
// Navigate to the website
driver.get("https://www.example.com");
// Create a FluentWait instance with a
timeout of 30 seconds
FluentWait<WebDriver> wait = new
FluentWait<>(driver)
.withTimeout(Duration.ofSeconds(30))
.pollingEvery(Duration.ofSeconds(1))
.ignoring(NoSuchElementException.class);
// Wait for the search box element to
become visible and clickable
WebElement searchBox =
wait.until(ExpectedConditions.and(
ExpectedConditions.visibilityOfElementLocated(By.name("q")),
ExpectedConditions.elementToBeClickable(By.name("q"))
));
// Enter a search query and submit the
form
searchBox.sendKeys("Selenium");
searchBox.submit();
// Close the browser
driver.quit();
}
}
In this example, we use the FluentWait class to create a
fluent wait period for the search box element. The withTimeout method specifies
the maximum amount of time to wait for the condition to be met, while the
pollingEvery method specifies the interval at which to check for the condition.
The ignoring method specifies any exceptions to be ignored during the wait
period. We then use the and method of the ExpectedConditions class to combine
two conditions: the visibility of the search box element, and the element being
clickable. This means that the fluent wait will wait for both conditions to be
met before returning the element. Using fluent wait allows us to wait for
multiple conditions to be met in a flexible and fluent way, and to ignore any
exceptions that may occur during the wait period. This helps to ensure that the
test script is synchronized with the behavior of the web application and avoids
errors or unexpected behavior caused by trying to interact with an element that
is not yet visible or clickable on the page.
6.
Where
to use each of the wait and what would be the benefit
Implicit Wait: If a website has a lot of dynamic
content, an implicit wait can be helpful to ensure that Selenium can find all
necessary elements on a page. This can be especially useful for pages that load
slowly or have a lot of AJAX calls. An implicit wait can also help to ensure
that Selenium does not throw an exception if a page takes longer to load than
expected. For example:
// Set a default implicit wait of 10 seconds
driver.manage().timeouts().implicitlyWait(10,
TimeUnit.SECONDS);
// Find an element using implicit wait
WebElement
element = driver.findElement(By.id("exampleElement"));
Explicit Wait: If a specific element needs to be
clicked or interacted with before proceeding to the next step in a test script,
an explicit wait can be helpful to ensure that the element is clickable before
proceeding. An explicit wait can also help to ensure that Selenium does not
throw an exception if an element takes longer to load than expected. For
example:
// Wait for up to 10 seconds for an element to be
clickable
WebElement
element = new WebDriverWait(driver, 10)
.until(ExpectedConditions.elementToBeClickable(By.id("exampleButton")));
// Click the element
element.click();
Fluent Wait: If a test requires waiting for
multiple elements to load before proceeding to the next step, a fluent wait can
be helpful to wait for multiple conditions to be met. A fluent wait can also
help to ensure that Selenium does not throw an exception if elements take
longer to load than expected. For example:
// Wait for up to 30 seconds for an element to be visible
and clickable, with a polling interval of 1 second
FluentWait<WebDriver>
wait = new FluentWait<>(driver)
.withTimeout(Duration.ofSeconds(30))
.pollingEvery(Duration.ofSeconds(1))
.ignoring(NoSuchElementException.class);
// Wait for both visibility and clickability of an
element before proceeding
WebElement
element = wait.until(ExpectedConditions.and(
ExpectedConditions.visibilityOfElementLocated(By.id("exampleElement")),
ExpectedConditions.elementToBeClickable(By.id("exampleElement"))));
In summary, the different types of waits in Selenium
provide flexibility and precision in waiting for elements to load or become clickable
and can help ensure that test scripts run smoothly and without errors. By using
the appropriate type of wait for each scenario, test scripts can be more
reliable and efficient.
7. Can you help me with a table detailing
the difference between different waits in Selenium?
|
Wait Type |
Description |
Usage |
|
Implicit
Wait |
Set
once per session and applied globally to all elements |
Used
to set a default wait time for all elements to be located |
|
Explicit
Wait |
Set
for a specific element or condition, and applied to that element or condition
only |
Used
when you need to wait for a specific element or condition to become available
before proceeding with the script |
|
Fluent
Wait |
Set
for a specific element or condition, and applied to that element or condition
only |
Used
when you need to wait for a specific element or condition to become available
before proceeding with the script, but want more control over the wait time
and polling frequency |
Note that while explicit and fluent waits are both used
for specific elements or conditions, the key difference is that explicit waits
are used to wait for a specific condition to occur, while fluent waits are used
to wait for a condition to occur with more fine-grained control over the
polling frequency and wait time. Additionally, implicit waits are set once per
session and applied globally to all elements, while explicit and fluent waits
are set on a per-element or per-condition basis.
Thread.sleep() is a method in Java that causes the current thread to sleep for a specified period of time. In the context of Selenium, it can be used to pause the execution of a test script for a given time. One example where you might use Thread.sleep() in Selenium is when you need to wait for a page to load before performing further actions. You can use Thread.sleep() to pause the script execution for a few seconds to give the page time to fully load before continuing with the script.
Here's an example of how you can use Thread.sleep() in Selenium:
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
public class ExampleTest {
public static void main(String[] args) throws InterruptedException {
System.setProperty("webdriver.chrome.driver", "path/to/chromedriver.exe");
WebDriver driver = new ChromeDriver();
driver.get("https://www.example.com");
Thread.sleep(5000); // wait for 5 seconds
WebElement element = driver.findElement(By.id("elementId"));
element.click();
driver.quit();
}
}
In this example, the script waits for 5 seconds after navigating to the https://www.example.com page before clicking on the element with the ID elementId. The Thread.sleep(5000) method call causes the script to pause for 5 seconds before continuing with the next line of code. Note that using Thread.sleep() is generally not the best approach for waiting for elements or pages to load in Selenium, as it can cause delays and make the test script brittle. Instead, you should consider using explicit or implicit waits, which are built-in methods in Selenium for waiting for elements to become available.
9.What is thread in Thread.sleep?
In Java, a thread is the smallest unit of execution that can be scheduled by the operating system. A thread is a lightweight process, and multiple threads can run concurrently within a single process. When you call the Thread.sleep() method in Java, it causes the currently executing thread to pause or sleep for a specified amount of time. During this time, the thread is blocked and does not execute any further code. In the context of Selenium, when you call Thread.sleep(), you are causing the current test script execution thread to pause for the specified time before continuing with the next line of code. This can be useful for adding a delay between steps in the test script or for waiting for an element or page to load before continuing with the test. However, as I mentioned earlier, there are better ways to wait for elements or pages to load in Selenium, such as using explicit or implicit waits.
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