Rails custom model validator fails rspec tests - ruby-on-rails

Question

I have a custom validator to verify the content of 2 fields in my database. When I use it through my UI, it works fine, however my rspec tests are failing and I can't understand why.
Here is the rspec test:
require 'rails_helper'
RSpec.describe Device, type: :model do
before(:each) { #user = User.create(email: 'test#test.com', password: 'password', password_confirmation: 'password') }
before(:each) { #device = Device.create(user_id: #user.id) }
subject { #device }
it { should allow_value('192.168.1.1').for(:ips_scan) }
it { should allow_value('192.168.1.1').for(:ips_exclude) }
it { should_not allow_value('192.168.1.1, a.b.c.d').for(:ips_scan) }
it { should_not allow_value('a.b.c.d').for(:ips_exclude) }
end
The Device model is:
class Device < ApplicationRecord
belongs_to :user
validates :ips_scan, :ips_exclude, ip: true, on: :update
end
And my ip_validator concern is:
class IpValidator < ActiveModel::Validator
def validate(record)
if record.ips_scan
ips = record.ips_scan.split(',')
ips.each do |ip|
/([0-9]{1,3}\.){3}[0-9]{1,3}(\/([1-2][0-9]|[0-9]|3[0-2]))?(-([0-9]{1,3}))?/ =~ ip
record.errors.add(:ips_scan, 'is not valid') unless $LAST_MATCH_INFO
end
end
if record.ips_exclude
ips = record.ips_exclude.split(',')
ips.each do |ip|
/([0-9]{1,3}\.){3}[0-9]{1,3}(\/([1-2][0-9]|[0-9]|3[0-2]))?(-([0-9]{1,3}))?/ =~ ip
record.errors.add(:ips_exclude, 'is not valid') unless $LAST_MATCH_INFO
end
end
end
end
Ironically, the validator is correctly passing the should_not allow_value tests, however the should allow_value tests are failing:
Failures:
1) Device should allow :ips_scan to be ‹"192.168.1.1"›
Failure/Error: it { should allow_value('192.168.1.1').for(:ips_scan) }
After setting :ips_scan to ‹"192.168.1.1"›, the matcher expected the
Device to be valid, but it was invalid instead, producing these
validation errors:
* ips_scan: ["is not valid"]
# ./spec/models/device_spec.rb:22:in `block (2 levels) in <top (required)>'
2) Device should allow :ips_exclude to be ‹"192.168.1.1"›
Failure/Error: it { should allow_value('192.168.1.1').for(:ips_exclude) }
After setting :ips_exclude to ‹"192.168.1.1"›, the matcher expected the
Device to be valid, but it was invalid instead, producing these
validation errors:
* ips_exclude: ["is not valid"]
# ./spec/models/device_spec.rb:23:in `block (2 levels) in <top (required)>'
At this point, I'm at a loss as to what is wrong now. Any help is much appreciated! Thx!

Answer 1

I found the solution. I don't know why, but the RSPEC doesn't know the $LAST_MATCH_INFO. If you replace it with $~, what it is actually is, it should work. At least, it works for me.
$LAST_MATCH_INFO is part of the library English which should be enabled in Rspec probably. But for me, the problem is resolved.