xvfb-manager

Java Xvfb manager. A library for managing an Xvfb process and a JUnit rule for using that library in unit or integration tests.

Quickstart - Core Library

Maven

<dependency>
    <groupId>com.github.mike10004</groupId>
    <artifactId>xvfb-manager</artifactId>
    <version>0.14</version>
</dependency>

Code

XvfbManager manager = new XvfbManager();
try (final XvfbController controller = manager.start()) {
    controller.waitUntilReady();
    // start a graphical program on a different thread
    Future<Process> processFuture = Executors.newSingleThreadExecutor().submit(new Callable<Process>(){
        @Override
        public Process call() throws Exception {
            ProcessBuilder pb = new ProcessBuilder();
            pb.environment().put("DISPLAY", controller.getDisplay());
            return pb.command("xclock").start();
        }
    });
    Screenshot screenshot = controller.getScreenshooter().capture();
    // do something with screenshot
    processFuture.cancel(true);
}

Quickstart - JUnit Rule

Maven

<dependency>
    <groupId>com.github.mike10004</groupId>
    <artifactId>xvfb-testing</artifactId>
    <version>0.4</version>
</dependency>

Code

@Rule
public XvfbRule xvfb = new XvfbRule();

@Test
public void testSomething() throws Exception {
    XvfbController controller = xvfb.getController();
    // use controller as in the core library example above
}

Modules

The purpose of each module is as follows:

• xvfb-manager: core library
• xvfb-testing: JUnit Rule
• xvfb-unittest-tools: library only used by above projects for testing
• xvfb-manager-example: executable program demonstrating Selenium usage

Using with Selenium

To use an XvfbManager instance with Selenium, start the virtual framebuffer and then configure the webdriver process's environment with the appropriate display. (There used to be an xvfb-selenium artifact that had a convenience method for this, but I didn't like keeping up with the Selenium API changes.)

Chrome

ChromeDriverService service = new ChromeDriverService.Builder()
        .usingAnyFreePort()
        .withEnvironment(ImmutableMap.of("DISPLAY", display))
        .build();
return new ChromeDriver(service);

Firefox

GeckoDriverService service = new GeckoDriverService.Builder()
        .usingAnyFreePort()
        .withEnvironment(ImmutableMap.of("DISPLAY", display))
        .build();
FirefoxDriver driver = new FirefoxDriver(service);

Notes

Automatic Display Selection

Versions of Xvfb prior to 1.13 did not support the -displayfd option that allows automatic selection of an open display number. If your version of Xvfb is lower than 1.13, then you must specify a display number. If using the core library, you would do that like this:

 XvfbManager manager = new XvfbManager();
 XvfbController controller = manager.start(99); 

If using the JUnit rule, then the display number is specified like this:

 public XvfbRule xvfb = XvfbRule.builder().onDisplay(99).build();

The display number 99 corresponds to the DISPLAY environment variable value :99.

Unit tests with Selenium

The unit tests that involve Selenium make use of WebDriverManager to manage webdrivers for Chrome and Firefox. This library queries the GitHub API and occasionally gets a 403 response due to rate-limiting of anonymous requests. To make your requests non-anonymous and prevent the rate-limiting from breaking the build:

1. Create a pair token/secret in your GitHub account
2. Set system properties wdm.gitHubTokenName and wdm.gitHubTokenSecret for the build

Supported Operating Systems

Currently only Linux is supported, and the library has only been tested on Ubuntu. In theory, it should work on Fedora-like platforms. Support for MacOS has not been investigated. Support for Windows probably wouldn't make sense.

Runtime and Unit Test Requirements

Some programs are required to be installed at runtime, and many tests will be skipped if certain programs are not available in the build environment. These prerequisites are listed in the table below by distribution.

Ubuntu 16.04	Fedora 24	Scope
xvfb	xorg-x11-server-Xvfb	runtime
netpbm	netpbm-progs	runtime
x11-utils	xorg-x11-utils	runtime
x11-apps	xorg-x11-apps	test
xdotool	xdotool	test
imagemagick	ImageMagick	test
firefox	firefox	test
google-chrome or chromium	google-chrome or chromium	test

FAQ

Does it work on MacOS?

Not really, but you might be able to shoehorn it. You can install [XQuartz] (see Homebrew instructions), but that version of Xvfb requires being run as root (for the creation of secure directories in /tmp), and you should be justifiably skeptical of anyone suggesting you run your unit tests as root. You might be able to get around this be manually creating /tmp/.X11-unix as root and setting its permissions to 1777 before you run your tests.

Acknowledgements

The photo used in the unit tests is by George Chernilevsky - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=34785750.