electron on Linux systems isn't really headless (i.e. needs X server)

[ryx]

Unlike phantomjs, nightmare currently requires an X environment to work on Linux host systems. This is a problem of the electron shell and the underlying Chromium browser, so we currently can't do much about it.

Obviously this makes the use of nightmare on most CI systems unnecessarily difficult. Using XFVB is a workaround for that, but makes the entire setup process a lot more complex and error-prone.

An example for running testcafe with nightmare through XVFB:

DEBUG=nightmare xvfb-run --server-args="-screen 0 1024x768x24" testcafe nightmare 'path/to/test.js'

See the following issues for more information:
segment-boneyard/nightmare#224
electron/electron#228

At least there's hope: Chromium on Linux supports a fully headless mode since early January 2017, which should land in electron sooner or later.