i want use "yarn " in my npm project
when run shell " yarn " in the shell,
it throw "ERROR: There are no scenarios; must have at least one. "

what problem?

yarn --version
0.27
node -v
v6.9.5
uname -a
Linux wfx-pc 4.4.0-3-deepin-amd64 #1 SMP Deepin 4.4.30-2 (2016-12-01) x86_64 GNU/Linux