Testing in Parallel

The Espresso driver supports running multiple sessions in parallel. This can be implemented in two ways:

• Multiple Appium server processes with a single session each
• Single Appium server process with multiple sessions (uses less resources and ensures better control over running sessions)

Note that a single device under test should only be used in one session at a time.

Tip

If testing in parallel is not required, consider enabling the --session-override Appium server flag, which ensures deletion of all existing sessions when a new one is started.

Important Capabilities

In order to avoid issues when running parallel sessions, several capabilities should be explicitly specified in each session, and must have a unique value among all parallel sessions:

• appium:udid
• appium:systemPort
• appium:chromedriverPort - if using hybrid/webview mode

Troubleshooting

If running tests on Jenkins, watch out for ProcessTreeKiller when running multiple parallel test jobs on the same machine. If you are spawning simulators in one test job, Jenkins might kill all your simulators when the first test ends - causing errors in the remaining test jobs!

In order to avoid this, set the BUILD_ID=dontKillMe environment variable.