module ActiveModel::Validations

person.valid?(:new) # => false
person.valid? # => true
person = Person.new

end
validates_presence_of :name, on: :new
attr_accessor :name

include ActiveModel::Validations
class Person

against (the context is defined on the validations using :on).
Context can optionally be supplied to define which callbacks to test

person.valid? # => true
person.name = 'david'
person.valid? # => false
person.name = ''
person = Person.new

end
validates_presence_of :name
attr_accessor :name

include ActiveModel::Validations
class Person

added otherwise +false+.
Runs all the specified validations and returns +true+ if no errors were

def valid?(context = nil)
  current_context = validation_context
  context_for_validation.context = context
  errors.clear
  run_validations!
ensure
  context_for_validation.context = current_context
end