How to execute tests in a single project only in multi-module build?

Run sbt commons/test. See detailed explanation in Scopes.

You may also use the combination of two commands from sbt - changing the current project using project and executing test afterwards.

sbt "project commons" test

You can also use

sbt "; project commons; test"

It you are running sbt in interactive mode:

> project commons
> test

You can switch back to core with:

> project core

Never mind, I came across this: How to execute package for one submodule only on Jenkins?

sbt "project core" test