Take Screenshot on Failure (Selenium Web Driver + JUnit + ExtJS)

First a little background: this is the first of a series of lessons I learned using Selenium Web Driver to test ExtJS web application.

It's usually desirable to always take a screenshot when test failed. The concept of JUnit rules makes this an easy task. First, implement a rule as shown below:

	public class TakeScreenshotOnFailRule extends TestWatcher {
	protected String _folder;
	protected WebDriver _driver;
	public TestRule(WebDriver driver, String folder) {
	_folder = folder;
	_driver = driver;
	}
	@Override
	protected void failed(Throwable e, Description description) {
	super.failed(e, description);
	String name = description.getDisplayName();
	name = _folder + "\\" + name + ".png";
	File screenshot = ((TakesScreenshot)_driver).getScreenshotAs(OutputType.FILE);
	try {
	FileUtils.copyFile(screenshot, new File(name));
	} catch (Exception ex) {
	throw new RuntimeException(ex);
	}
	}
	}

view raw TakeScreenshotOnFailRule.java hosted with ❤ by GitHub

Then in your test classes, you just need to declare this rule, then all test methods in it will automatically take screenshot on failure.

	@Rule
	public TakeScreenshotOnFailRule rule = new TakeScreenshotOnFailRule(driver, folderName);

view raw gistfile1.java hosted with ❤ by GitHub

The examples here are just for illustration purpose. In real world application, you might make some improvement like:

• Make sure the file name is legal for the OS (for example, the following characters are not allowed in Windows file name: \/:?*<>|\
• Pictures might be further organized into folders by test cases?
• The rule might be declared in a base class so that all test cases have the same behavior without extra boiler plate code