Is merge performed automatically on Pull Request Action?

Whenever a Pull Request is initiated to merge into master, I want to run a workflow. I want to build/test my code on the merged branches; i.e., after it is locally merged into master. 

When I tested with travis-ci, this was done automatically. I’m wondering if I have to do the merge myself or if there is some magic action that will do it for me.

Please advise.

The answer to this is that actions/checkout@v2 knows what is happening and does the merge for you so you don’t have to do it. That’s quite nice.