Webdriver Containers

Test Containers can be used to automatically instantiate and manage containers that include web browsers, such as those from SeleniumHQ's docker-selenium project.

Benefits

  • Fully compatible with Selenium 2/Webdriver tests, by providing a RemoteWebDriver instance
  • No need to have specific web browsers, or even a desktop environment, installed on test servers. The only dependency is a working Docker installation and your Java JUnit test suite.
  • Browsers are always launched from a fixed, clean image. This means no configuration drift from user changes or automatic browser upgrades.
  • Compatibility between browser version and the Selenium API is assured: a compatible version of the browser docker images will be automatically selected to match the version of selenium-api-*.jar on the classpath
  • Additionally the use of a clean browser prevents leakage of cookies, cached data or other state between tests.
  • VNC screen recording: Test Containers can automatically record video of test runs (optionally capturing just failing tests)

Creation of browser containers is fast, so it's actually quite feasible to have a totally fresh browser instance for every test.

Example

The following field in your JUnit UI test class will prepare a container running Chrome:

@Rule
public BrowserWebDriverContainer chrome =
    new BrowserWebDriverContainer()
            .withDesiredCapabilities(DesiredCapabilities.chrome());

Now, instead of instantiating an instance of WebDriver directly, use the following to obtain an instance inside your test methods:

RemoteWebDriver driver = chrome.getWebDriver();

You can then use this driver instance like a regular WebDriver.

Note that, if you want to test a web application running on the host machine (the machine the JUnit tests are running on - which is quite likely), you'll need to replace any references to localhost with an IP address that the Docker container can reach. Use the getHostIpAddress() method, e.g.:

driver.get("http://" + chrome.getHostIpAddress() + ":8080/");

Options

Other browsers

At the moment, Chrome and Firefox are supported. To switch, simply change the first parameter to the rule constructor:

new BrowserWebDriverContainer()
                .withDesiredCapabilities(DesiredCapabilities.chrome());

or

new BrowserWebDriverContainer()
                .withDesiredCapabilities(DesiredCapabilities.firefox());

Recording videos

By default, no videos will be recorded. However, you can instruct Test Containers to capture videos for all tests or just for failing tests.

To do this, simply add extra parameters to the rule constructor:

new BrowserWebDriverContainer()
                .withDesiredCapabilities(DesiredCapabilities.chrome())
                .withRecordingMode(VncRecordingMode.RECORD_ALL, new File("./target/"))

or if you only want videos for test failures:

new BrowserWebDriverContainer()
                .withDesiredCapabilities(DesiredCapabilities.chrome())
                .withRecordingMode(VncRecordingMode.RECORD_FAILING, new File("./target/"))

Note that the seconds parameter to withRecordingMode should be a directory where recordings can be saved.

More examples

A few different examples are shown in ChromeWebDriverContainerTest.java.

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