Add a way to test GraphQL in integration test

What does this MR do and why?

Add a way to test GraphQL in integration test

This should catch that the GraphQL client we're using will freeze the response so we cannot mutate the response.

See #343 (closed)

This should catch #338 (closed) as well.

This should complement !314 (merged) and I think we can remove the artificial freeze on those string literals.