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Selenium Javatesting~15 mins

Docker Selenium Grid in Selenium Java - Build an Automation Script

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Verify Google Search using Selenium Grid on Docker
Preconditions (3)
Step 1: Start Docker Selenium Grid Hub container
Step 2: Start Docker Selenium Grid Node Chrome container connected to the Hub
Step 3: Write a Selenium test that connects to the Selenium Grid Hub URL
Step 4: Navigate to https://www.google.com
Step 5: Enter 'Selenium Grid Docker' in the search input field
Step 6: Submit the search form
Step 7: Wait for the results page to load
Step 8: Verify that the page title contains 'Selenium Grid Docker'
✅ Expected Result: The test connects to the Selenium Grid running in Docker, performs a Google search, and verifies the page title contains the search term, indicating the test ran successfully on the remote browser.
Automation Requirements - Selenium WebDriver with Java
Assertions Needed:
Verify page title contains the search term 'Selenium Grid Docker'
Best Practices:
Use RemoteWebDriver to connect to Selenium Grid Hub URL
Use explicit waits to wait for page elements or title
Use proper locator strategies (By.name for search input)
Close the WebDriver session after test completion
Automated Solution
Selenium Java
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.remote.RemoteWebDriver;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

import java.net.URL;
import java.time.Duration;

public class GoogleSearchGridTest {
    public static void main(String[] args) throws Exception {
        // URL of the Selenium Grid Hub running in Docker
        URL gridUrl = new URL("http://localhost:4444/wd/hub");

        // Desired capabilities for Chrome browser
        DesiredCapabilities capabilities = new DesiredCapabilities();
        capabilities.setBrowserName("chrome");

        // Create RemoteWebDriver instance to connect to Grid
        WebDriver driver = new RemoteWebDriver(gridUrl, capabilities);

        try {
            // Navigate to Google
            driver.get("https://www.google.com");

            // Wait for the search box to be visible
            WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
            WebElement searchBox = wait.until(ExpectedConditions.visibilityOfElementLocated(By.name("q")));

            // Enter search text
            String searchTerm = "Selenium Grid Docker";
            searchBox.sendKeys(searchTerm);

            // Submit the search form
            searchBox.submit();

            // Wait for the title to contain the search term
            wait.until(ExpectedConditions.titleContains(searchTerm));

            // Assertion: verify title contains search term
            if (driver.getTitle().contains(searchTerm)) {
                System.out.println("Test Passed: Title contains search term.");
            } else {
                System.out.println("Test Failed: Title does not contain search term.");
            }
        } finally {
            // Close the browser session
            driver.quit();
        }
    }
}

This Java program uses Selenium WebDriver to connect to a Selenium Grid Hub running in Docker at http://localhost:4444/wd/hub. It sets the desired browser to Chrome.

The test navigates to Google, waits explicitly for the search input box to appear, enters the search term "Selenium Grid Docker", and submits the form.

It then waits until the page title contains the search term, which confirms the search results loaded correctly.

Finally, it asserts the page title contains the search term and prints the test result. The WebDriver session is closed in a finally block to ensure cleanup.

This approach uses explicit waits and proper locator strategies, following best practices for Selenium Grid tests.

Common Mistakes - 4 Pitfalls
Using local WebDriver instead of RemoteWebDriver to connect to Selenium Grid
Hardcoding Thread.sleep() instead of using explicit waits
{'mistake': 'Using brittle locators like absolute XPath for the Google search box', 'why_bad': 'Absolute XPath can break easily if page structure changes, making tests fragile.', 'correct_approach': 'Use stable locators like By.name("q") for the Google search input.'}
Not closing the WebDriver session after test completion
Bonus Challenge

Now add data-driven testing with 3 different search terms: 'Selenium Grid Docker', 'Docker containers', 'RemoteWebDriver Java'

Show Hint

Practice

(1/5)
1. What is the main purpose of using Docker Selenium Grid in automated testing?
easy
A. To debug Java code in Selenium tests
B. To write test scripts faster
C. To replace Selenium WebDriver completely
D. To run tests on multiple browsers and machines simultaneously

Solution

  1. Step 1: Understand Docker Selenium Grid's role

    Docker Selenium Grid allows running tests on different browsers and machines at the same time, improving test coverage and speed.
  2. Step 2: Compare options with this purpose

    Only To run tests on multiple browsers and machines simultaneously matches this main purpose. Options B, C, and D describe unrelated or incorrect uses.
  3. Final Answer:

    To run tests on multiple browsers and machines simultaneously -> Option D
  4. Quick Check:

    Purpose = run tests on many browsers [OK]
Hint: Docker Selenium Grid = run tests on many browsers [OK]
Common Mistakes:
  • Thinking it speeds up writing tests
  • Confusing it with Selenium WebDriver itself
  • Assuming it is for debugging code
2. Which Docker command correctly starts a Selenium Grid Hub container?
easy
A. docker start selenium/node-chrome
B. docker build -t selenium/hub .
C. docker run -d -p 4444:4444 selenium/hub
D. docker stop selenium/hub

Solution

  1. Step 1: Identify the command to run a container

    The command to start a container in detached mode and map port 4444 is 'docker run -d -p 4444:4444 selenium/hub'.
  2. Step 2: Check other options

    docker start selenium/node-chrome starts an existing container, C builds an image, and D stops a container. Only B starts the hub container correctly.
  3. Final Answer:

    docker run -d -p 4444:4444 selenium/hub -> Option C
  4. Quick Check:

    Start hub = docker run -d -p 4444:4444 selenium/hub [OK]
Hint: Use 'docker run -d -p 4444:4444 selenium/hub' to start hub [OK]
Common Mistakes:
  • Using 'docker start' instead of 'docker run' to create container
  • Confusing build and run commands
  • Stopping instead of starting the container
3. Given this Java code snippet connecting to a Docker Selenium Grid hub:
RemoteWebDriver driver = new RemoteWebDriver(
  new URL("http://localhost:4444/wd/hub"),
  new ChromeOptions()
);
driver.get("https://example.com");
System.out.println(driver.getTitle());

What will be printed if the page title is "Example Domain"?
medium
A. Example Domain
B. http://localhost:4444/wd/hub
C. null
D. NoSuchSessionException

Solution

  1. Step 1: Understand RemoteWebDriver usage

    The code creates a RemoteWebDriver connected to the Selenium Grid hub URL and opens the page https://example.com.
  2. Step 2: Check what driver.getTitle() returns

    driver.getTitle() returns the page title, which is "Example Domain" for that URL.
  3. Final Answer:

    Example Domain -> Option A
  4. Quick Check:

    driver.getTitle() = page title [OK]
Hint: driver.getTitle() prints page title loaded [OK]
Common Mistakes:
  • Confusing URL with page title
  • Expecting null if no errors
  • Assuming exceptions without errors
4. You run this command to start a Chrome node:
docker run -d --link selenium-hub:hub selenium/node-chrome

But your tests fail to connect to the node. What is the likely problem?
medium
A. The Docker daemon is stopped
B. The node container is not linked properly to the hub
C. The Chrome browser is not installed inside the node container
D. The hub container is not running

Solution

  1. Step 1: Analyze the linking option

    The '--link' option is deprecated and may not correctly link the node to the hub, causing connection failure.
  2. Step 2: Check other possible causes

    Docker daemon (A) or hub not running (B) issues would cause broader failures. Chrome is preinstalled in official node images (C) so unlikely cause.
  3. Final Answer:

    The node container is not linked properly to the hub -> Option B
  4. Quick Check:

    Deprecated --link causes node-hub connection fail [OK]
Hint: Avoid deprecated --link; use network for node-hub [OK]
Common Mistakes:
  • Assuming Chrome is missing inside node container
  • Ignoring hub container status
  • Not checking Docker daemon status
5. You want to run tests on Chrome and Firefox browsers simultaneously using Docker Selenium Grid. Which setup is correct?
hard
A. Start hub container, then start both selenium/node-chrome and selenium/node-firefox containers connected to the hub network
B. Start only selenium/node-chrome container; Firefox tests will run on Chrome node
C. Start hub container and run tests locally without nodes
D. Start selenium/node-firefox container first, then hub container

Solution

  1. Step 1: Understand multi-browser setup

    To run tests on multiple browsers, you must start the hub and connect nodes for each browser to the hub's network.
  2. Step 2: Evaluate options

    Start hub container, then start both selenium/node-chrome and selenium/node-firefox containers connected to the hub network correctly starts hub and both browser nodes connected properly. Start only selenium/node-chrome container; Firefox tests will run on Chrome node misses Firefox node, A misses nodes, and D starts nodes before hub which is incorrect.
  3. Final Answer:

    Start hub container, then start both selenium/node-chrome and selenium/node-firefox containers connected to the hub network -> Option A
  4. Quick Check:

    Hub + all browser nodes connected = multi-browser tests [OK]
Hint: Start hub first, then all browser nodes on same network [OK]
Common Mistakes:
  • Starting nodes before hub
  • Running tests without nodes
  • Assuming one node can run all browsers
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10 questions~5 mineasy hard