validate_uniqueness_of boolean column

[aaronmallen]

Getting the following error when trying to conditionally validate a boolean value:

NoMethodError:
       undefined method `attribute_setter' for nil:NilClass

Given an environment with:

$ ruby -v
ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17]
$ rails -v
Rails 5.1.4

# Gemfile.lock
shoulda-matchers (3.1.2)
rspec-core (3.7.1)

given a class with a boolean column

# foo.rb
#
# == Schema Information
#
# Table name: foo
#
#  id               :integer    not null, primary key
#  some_bool_val    :boolean    not null
class Foo < ApplicationRecord
  validates :some_bool_val, inclusion: { in: [true, false], allow_nil: false, allow_blank: false },
                            uniqueness: { if: :some_bool_val }
end

and a spec

# foo_spec.rb

RSpec.describe Foo, type: :model do
  # this test passes
  context 'with some_bool_val true' do
    subject { create(:foo, some_bool_val: true) }
    it { should validate_uniqueness_of :some_bool_val }
  end

  # this test produces the error
  context 'with some_bool_value false' do
    subject { create(:foo, some_bool_val: false) }
    it { should_not validate_uniqueness_of :some_bool_val }
  end
end

full trace:

Failures:

  1) Foo with some_bool_value false should not validate that :some_bool_value is case-sensitively unique
     Failure/Error: it { should_not validate_uniqueness_of :some_bool_value }

     NoMethodError:
       undefined method `attribute_setter' for nil:NilClass
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_model/allow_value_matcher.rb:405:in `failure_message'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_model/disallow_value_matcher.rb:69:in `failure_message_when_negated'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_model/validation_matcher.rb:133:in `failure_reason_when_negated'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb:346:in `failure_reason_when_negated'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_model/validation_matcher.rb:68:in `block in failure_message_when_negated'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_model/validation_matcher.rb:67:in `tap'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/shoulda-matchers-3.1.2/lib/shoulda/matchers/active_model/validation_matcher.rb:67:in `failure_message_when_negated'
     # ./spec/models/foo_spec.rb:67:in `block (3 levels) in <top (required)>'
     # ./spec/support/database_cleaner.rb:12:in `block (3 levels) in <top (required)>'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/database_cleaner-1.6.2/lib/database_cleaner/generic/base.rb:16:in `cleaning'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/database_cleaner-1.6.2/lib/database_cleaner/base.rb:98:in `cleaning'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/database_cleaner-1.6.2/lib/database_cleaner/configuration.rb:86:in `block (2 levels) in cleaning'
     # $HOME/.rvm/gems/ruby-2.5.0@my-project/gems/database_cleaner-1.6.2/lib/database_cleaner/configuration.rb:87:in `cleaning'
     # ./spec/support/database_cleaner.rb:11:in `block (2 levels) in <top (required)>'

Finished in 3.62 seconds (files took 3.53 seconds to load)
165 examples, 1 failure, 1 pending

Failed examples:

rspec ./spec/models/foo_spec.rb:67 # Foo with some_bool_value false should not validate that :some_bool_value is case-sensitively unique

Randomized with seed 53832

[mcmire]

@aaronmallen Thanks for reminding me about this. A lot of people have reported this -- #904 contains a bunch of references -- so if you don't mind I'm going to close this in favor of that. I have a branch going that fixes this bug and provides more information in case of a failure, so I'll have that done soon.