The question mark isn't being used to end a question, he's using it to ask for confirmation of a statement. He's writing in a way that mimics how people talk to each when they meet face-to-face.

For example:

    Jack: I wonder what Jill's favourite flavour of ice cream is.
    Sam:  Chocolate?
    Jack: Yes, that's the one.

"Data integrity testing was being performed?" I expect.