'with an argument that responds to #to_hash
Update RSpec version
This pull request fails (merged da4df6e into f21b149).
Update Guard as well
It fails on ruby-head. I guess it's OK, since ruby-head might not be stable.
Unfortunately we rely on old rspec as it works with heckle that we use for mutation testing. Once mutant is ready we will switch to latest rspec and abandon heckle.
I'll finish mutant once I have time. Currently busy with commercial stuff. Expect something tomorrow as we have a free day here in germany.