How do I `expect` something which raises exception in RSpec?

You can chain positive assertions with and. If you want to mix in a negated one in the chain, RSpec 3.1 introduced define_negated_matcher.

You could do something like:

RSpec::Matchers.define_negated_matcher :not_change, :change

expect { eat(what: nil) }
  .to raise_error
  .and not_change(cat, :status)

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