How to add functionGlobalContext to node-red-node-test-helper?

I am trying to write tests for my flow. My flow uses a function node, which uses a global.get() call to load a module which was specified in the settings.functionGlobalContext.

At the moment my test fails because with the node-red-node-test-helper, global.get() returns undefined. Is there a way to specify the functionGlobalContext for the node-red-node-test-helper?