This directory can be used to override the default configuration from
test-config.sh. Just create one or more files
ending in .sh, set variables in those files and then those variables
will override the defaults.
The files are sourced in a bash shell and thus can use arbitrary shell
constructs like if/else/fi.
To set defaults that can still be overridden by environment variables, use this idiom:
: ${TEST_DEVICEMODE:=direct}