Rails bug?

rails_bug.rb

# Was super struggling to get my array to validate (nil is bad, empty array is fine, nonempty array should contain strings)
# Finally went and read the code, and it looked totally buggy (b/c `nil` is `blank?`:
# https://github.com/rails/rails/blob/25b126707152de3a1ec9762ee564f3c7623373b3/activemodel/lib/active_model/validator.rb#L151
# Made this test to demonstrate.

require 'active_model'

def test(*values, **validation)
  [false, true].product([false, true]).map.with_index 1 do |(allow_nil, allow_blank), index|
    klass = Struct.new(:values, keyword_init: true) { include ActiveModel::Validations }
    klass.validates :values, allow_nil: allow_nil, allow_blank: allow_blank, **validation
    "%d | allow_blank: %-5p | allow_nil: %-5p | values: #{values.map { "#{_1.inspect}=%-5p" }.join(' ')}" % [
      index, allow_nil, allow_blank, *values.map { klass.new(values: _1).valid? },
    ]
  end
end

# 1: blank is not allowed, but `[]` is valid
# 2: blank is not allowed, but `[]` is valid
# 3: `nil` is not allowed, but is valid
test [], nil, length: { minimum: 0 }
# => ["1 | allow_blank: false | allow_nil: false | values: []=true  nil=false",
#     "2 | allow_blank: false | allow_nil: true  | values: []=true  nil=true ",
#     "3 | allow_blank: true  | allow_nil: false | values: []=true  nil=true ",
#     "4 | allow_blank: true  | allow_nil: true  | values: []=true  nil=true "]

# 2: blank is not allowed, but `''` is valid
# 3: blank is allowed, but is invalid
# 3: `nil` is not allowed, but is valid
test '', nil, format: /x/
# => ["1 | allow_blank: false | allow_nil: false | values: \"\"=false nil=false",
#     "2 | allow_blank: false | allow_nil: true  | values: \"\"=true  nil=true ",
#     "3 | allow_blank: true  | allow_nil: false | values: \"\"=false nil=true ",
#     "4 | allow_blank: true  | allow_nil: true  | values: \"\"=true  nil=true "]

# Some others I tried that were incorrect in the same way as the `format` example
test [], nil, presence: true
test [], nil, acceptance: true