How to call executeOperation when queries/mutations are defined in schema files and not strings

I am needing to start designing out some tests for our schemas. I looked into the apollo page on integration testing and it is what I am looking for, however, their example only shows executing a query that is defined as a string. This of course makes things difficult when we define our schemas in their own graphql schema files.
Is there a methodology for testing file defined schemas with apollo server?