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Getting Started With Visual Regression Testing Using Selenium On SmartUI

Using the LambdaTest platform, perform regression testing in just one click and find Visual UI Regression bugs easily with the help of Smart Testing. This documentation will act as your step-by-step guide in performing successful Visual Regression tests.

  • Basic understanding of Selenium and WebDriver is required.
  • Go to LambdaTest SmartUI and login along with your credentials.
  • Access your Hub for your selenium remote connection instance at
  • Copy LT_USERNAME and LT_ACCESS_KEY credentials from Access Key button on the top right of the dashboard.

The following steps will guide you in running your first Visual Regression test on LambdaTest platform -

Step 1: Create a SmartUI Project

The first step is to create a project with the application in which we will combine all your builds run on the project. To create a SmartUI Project, follow these steps:

  1. Go to Projects page
  2. Click on the new project button
  3. Select the platform as Web for executing your Selenium tests.
  4. Add name of the project, approvers for the changes found, tags for any filter or easy navigation.
  5. Click on the Submit.

Step 2: Configure your test with Selenium Desired Capabilities

Once you have created a SmartUI Project, you can generate screenshots by running automation scripts. Follow the below steps to successfully generate screenshots -

  1. Please clone the following sample Github repo (
git clone
  1. Set up the LambdaTest credentials by following the instructions mentioned in the file.
  2. Edit the required capabilities for your test suite.
Please replace your capabilities in your Remote Webdriver DesiredCapabilities configuration
let capabilities = {
platform: "Windows 10", // Configure your OS for Selenium test
browserName: "chrome", // Configure your Browser for Selenium test
version: "latest", // Configure your Browser Version for Selenium test
visual: true, // Configure your Capture screenshot for Selenium test
name: "test session", // name of the test for Selenium
build: "Automation Build", // name of the build for Selenium
"smartUI.project": "<Your Project Name>", // Replace the name of project with the new project name
"": "<Your Build Name>", // Replace the name of Build with the new Build name
"smartUI.baseline": false, // Enable if you want to update to a new baseline build

// Connecting to the Lambdatest Selenium Cloud Grid with Smart UI
let gridUrl =
"https://" +
"<Your Username>" +
":" +
"<Your Access Key>" +

// Here is your Remote WebDrive Connection
let driver = await new webdriver.Builder()
  • Installing dependency and for executing the test.
npm i && node <file_name>

Here you can explore multiple features and execute more such builds.

Step 3: Configure your Screenshot Capturing Options

For taking viewport screenshot

This part of the code needs to be attached below the required segment of selenium script of which we would like to take the screenshot to test on.

let config = {
screenshotName: '<Name of your screenshot>'
await driver.executeScript("smartui.takeScreenshot", config);

For capturing full page screenshot

You can capture the full page screenshot for all different websites which have a scrolling functionality on their application user interface for your Selenium functional testing.

Add the following Webhook to your test cases where we need to capture the screenshot of your application.

driver.executeScript("smartui.takeFullPageScreenshot=<Your Screenshot Name>")

The following feature is applicable for Selenium >= 4.0.0 with Chrome versions only. Please ensure that the Lambdatest Capabilities are updated in your project for executing full page screenshot(s).

SmartScroll (For browsers other than Chrome) BETA

For browsers other than chrome (Mozilla, Safari etc.) and for websites Full Page Screenshot fails, you can use smartscroll to take a full page screenshot of your web page by adding this hook in your test script.

await driver.executeScript("smartui.takeFullPageScreenshot,{\"screenshotName\":\"<screenshot-name>\", \"smartScroll\":true }");

For capturing the screenshot of a specific element

You can capture screenshots of targeted elements by leveraging various locator mechanisms such as XPath, CSS ID, class, and selectors. This precision-driven approach ensures accurate and specific visual regression testing for your web application.

Add the following Webhook to your test cases where you need to capture the screenshot of a particular element on your UI.

let config = {
screenshotName: '<Screenshot Name>',
elementType: 'xpath'/'css_selector'/'id'/'class', //Choose one from the following options - xpath, css_selector, id or class
element: '<Required Element>' //Add your required element here
await driver.executeScript("smartui.takeScreenshot", config);

Step 4: View SmartUI Results

You have successfully integrated SmartUI with your Selenium tests. Visit your SmartUI project to view builds and compare snapshots between different test runs.

You can see the Smart UI dashboard to view the results. This will help you identify the mis-matches from the existing Baseline build and do the required visual testing.

Fetching Screenshot Status and Results using WebHook

You can fetch the status of the screenshot captured and the results of the screenshot captured using the following webhook.


For fetching results specific to a screenshot, you can use the following webhook by adding the Screenshot Name to the WebHook.

driver.executeScript("smartui.fetchScreenshotStatus=<Your Screenshot Name>")
The following webhook will return the status of the screenshot captured. The status can be one of the following:
screenshotsData: [
screenshotName: '<Your Screenshot Name>',
screenshotURL: '<Link to the screenshot captured>',
screenshotStatus: 'Changes found', // Status of the screenshot
misMatchPercentage: 10.04, // Percentage of mismatch in the screenshot
threshold: 100, // Threshold set for the screenshot
browserName: 'chrome', // Browser used for capturing the screenshot
resolution: '1920x1080' // Resolution of the screenshot

../Other Screenshots
buildId: '<Your Build ID>',
buildName: '<Your Build Name>',
projectName: '<Name of the Project>'

The following are the description of the parameters:

screenshotNameName of the screenshot for which the result is to be fetched.
screenshotURLURL of the screenshot captured.
screenshotStatusStatus of the screenshot captured.
misMatchPercentagePercentage of mismatch in the screenshot captured.
thresholdThreshold set for the screenshot captured.
browserNameBrowser used for capturing the screenshot.
resolutionResolution of the screenshot captured.
buildIdID of the build in which the screenshot was captured.
buildNameName of the build in which the screenshot was captured.
projectNameName of the project in which the screenshot was captured.
Please Note

The webhook will return the result of the screenshot captured only if the screenshot is processed and the result is available.

This may take a few seconds to process the screenshot. Please ensure that you have added a delay before fetching the result of the screenshot.

Advanced Options for Screenshot Comparison

Build Configuration - If you have multiple screenshots running the same test suite and want to run the comparison for the same test suite, want to add a build as a baseline from your test suite or need to access more SmartUI Build Config Options, click here.

Advanced Test Settings - We offer multiple options for comparing the Baseline and the Test Output screenshots captured during your automation testing suites. To know more about our advanced P2P comparison options, click here.

Handling Dynamic Data - In case if you have any dynamic elements that are not in the same position across test runs, you can ignore or select a specific area to be removed from the comparison. For accessing such HTML DOM Config and Options, click here.