publishable_assignment_validation.rb

class PublishableAssignmentValidation
  attr_reader :assignment
  
  def initialize(assignment)
    @assignment = assignment
  end
  
  def valid?
    validate
    assignment.errors.none?
  end

  def validate
    AssignmentNotPublishedValidator.new.validate(assignment)
    HasAtLeastOneTaskValidator.new.validate(assignment)
    HasAtLeastOneAssigneeValidator.new.validate(assignment)
    GradedTasksHaveRubricValidator.new.validate(assignment)
    RubricItemsHaveRequiredAttributesValidator.new.validate(assignment)
  end
end
  
class HasAtLeastOneTaskValidator
  def validate(record)
    record.errors.add(:assignment, "must have at least 1 task") if record.tasks.empty?
  end
end