class Shoulda::Matchers::ActiveModel::NonNullableBooleanError

def self.create(attribute)
  super(attribute: attribute)
end

def message
  <<-EOT.strip
 specified that your model's #{attribute} should ensure inclusion of nil.
 #{attribute} is a boolean column which does not allow null values.
his test will fail and there is no way to make it pass.
  EOT
end