> Markdown version of [Headless Testing](https://vaadin.com/docs/v8/testbench/environment/testbench-headless). Section index: [llms.txt](https://vaadin.com/docs/v8/testbench/llms.txt)

# <a id="testbench.headless"></a>Headless Testing

TestBench (3.1 and later) supports fully-featured headless testing with PhantomJS ( <https://phantomjs.org>), a headless browser based on WebKit. It has fast native support for various web standards: JavaScript, DOM handling, CSS selector, JSON, Canvas, and SVG.

Headless testing using PhantomJS allows for around 15% faster test execution without having to start a graphical web browser, even when performing screenshot-based testing! This also makes it possible to run full-scale functional tests on the front-end directly on a build server, without the need to install any web browsers.

It is usually best to use a graphical browser to develop the test cases, as it is possible to see interactively what happens while the tests are being executed. Once the tests are working correctly in a graphical browser, you can migrate them to run on the PhantomJS headless browser.

## <a id="testbench.headless.running"></a>Basic Setup for Running Headless Tests

The only set up required is to install the PhantomJS binary. Follow the instructions for your operating system at [PhantomJS download page](https://phantomjs.org/download.html), and place the binary in the system path.

The PhantomJSDriver dependency is already included in Vaadin TestBench.

### <a id="testbench.headless.running.createwebdriver"></a>Creating a Headless WebDriver Instance

Creating an instance of the PhantomJSDriver is just as easy as creating an instance of FirefoxDriver.

```
setDriver(TestBench.createDriver(
    new PhantomJSDriver()));
```

Some tests may fail because of the small default window size in PhantomJS. Such tests are, for example, tests containing elements that pop up and might go off-screen when the window is small. To make them work better, specify a size for the window:

```
getDriver().manage().window().setSize(
        new Dimension(1024, 768));
```

Nothing else is needed to run tests headlessly.

## <a id="testbench.headless.grid"></a>Running Headless Tests in a Distributed Environment

Running PhantomJS in a distributed grid is equally easy. First, install PhantomJS in the nodes by following the instructions in [Basic Setup for Running Headless Tests](#testbench.headless.running). Then, start PhantomJS using the following command:

```
phantomjs --webdriver=8080 \
          --webdriver-selenium-grid-hub=http://127.0.0.1:4444
```

The above will start PhantomJS in the WebDriver mode and register it with a grid hub running at 127.0.0.1:4444. After this, running tests in the grid is as easy as passing DesiredCapabilities.phantomjs() to the RemoteWebDriver constructor.

```
setDriver(new RemoteWebDriver(
        DesiredCapabilities.phantomjs()));
```