I was fed up with "expected valid? to return true". Now you get errors

custom_validation_matcher.rb

module CustomValidationMatcher

  class IsValid
    def matches?(target)
      @target = target
      @target.valid?
    end

    def failure_message
      "expected #{ @target.class.name } to be in valid, errors were: #{ @target.errors.full_messages.inspect }"
    end

    def negative_failure_message
      "expected #{ @target.class.name } not to be valid"
    end
  end

  def be_valid
    IsValid.new
  end

end