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Testing web apps in C# using LeanFT

The Applitools Eyes LeanFT C# SDK allows you to easily add visual checkpoints to your C# LeanFT tests. It takes care of getting screenshots of your application from the underlying LeanFT, sending them to the Eyes server for validation and failing the test in case differences are found.

Install the SDK

Install-Package Eyes.LeanFT

Run your first test

Applitools Eyes reports differences by comparing screenshots of your application with baseline images that define the expected appearance of the application at each step of the test. By default, the Eyes SDK detects the environment in which the application is running (namely, the operating system, the type of browser and its viewport size) and compares the screenshots against baseline images that are specific to that environment. The first time you run a test in a given environment, its screenshots will be automatically saved as its baseline. Starting from the second run onward, you always have a baseline to compare against.

The test below is a simple program that visually validates the Hello World web-page at It consists of two visual checkpoints, each validating the entire application window. The first time you run this test a new baseline will be created, and subsequent test runs will be compared to this baseline. If any screenshot mismatch its baseline image in a perceptible way, $eyes.close() will throw a DiffsFoundException which includes a URL that points to a detailed report where you can see the detected differences and take appropriate actions such as reporting bugs, updating the baseline and more.

Before running the test, make sure to set the API key that identifies your account in the environment variable APPLITOOLS_API_KEY or directly assign it to the eyes.api_key property. You can find your API key under the user menu located at the right hand side of the test manager toolbar. If you don't yet have an account create it now to obtain your key.

namespace Applitools
using System;
using System.Drawing;
using HP.LFT.SDK.Web;
using HP.LFT.SDK;

public class HelloWorldTest
public static void Main(string[] args)
// Init the LeanFT SDK
SDK.Init(new SdkConfiguration());

// Open a Chrome browser
IBrowser testBrowser = BrowserFactory.Launch(BrowserType.Chrome);

// Initialize the eyes SDK and set your private API key.
var eyes = new Eyes();
eyes.ApiKey = "YOUR_API_KEY";

// Start the test and set the browser's viewport size to 800x600
eyes.Open(testBrowser, "Hello World!", "My first LeanFT C# test", new Size(800, 600));

// Navigate the browser to the "hello world!" web-site.

// Visual checkpoint #1

// Click the "Click me!" button
IWebElement button = testBrowser.FindChildren<IWebElement>(new WebElementDescription { TagName = "button" })[0];

// Visual checkpoint #2

// End the test
catch (Exception ex)
// Close the browser.

// If the test was aborted before eyes.Close was called, ends the test as aborted.

// Close the LeanFT SDK

Analyze your test results

Congratulations! You've successfully run your first visual UI test with Applitools Eyes! A detailed report is ready for your inspection at the Applitools Eyes test manager. Watch this 5 minute video to get acquainted with the test manager and to learn the basics of baseline maintenance.

Login to Applitools and analyze the results.

Having Trouble?

Don't suffer in silence! Let us help you. Please reach out to us to get your project working.

Taking the next steps with Applitools

Congratulations on completing this quickstart! There's still so much to learn about visual testing with Applitools, but you're off to a great start.

Resources for next steps:

  1. 🤖 Learning how visual testing works
  2. ↔️ Setting match levels for visual checkpoints
  3. 💥 Troubleshooting common issues
  4. 🐞 Reporting bugs
  5. 🗺 Detailed overview of visual testing with Applitools

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