Failing user validation with nested attributes and polymorphic association - ruby-on-rails

Question

This simple validation test is failing:
require 'test_helper'
class UserTest < ActiveSupport::TestCase
def setup
#user = User.new(name: "Example User",
email: "user#example.com",
character_attributes: {callsign: "example"},
password: "foobar",
password_confirmation: "foobar"
)
end
test "should be valid" do
assert #user.valid?, "#{#user.errors.messages}"
end
end
...with this message: character.sociable_id"=>["can't be blank"]
I don't understand why the user creation in UserTest is failing to make a valid User.
Each User has_one :character and each Character belongs_to a User.
The User model:
User.rb:
class User < ActiveRecord::Base
attr_accessor :remember_token, :activation_token, :reset_token
has_one :character, as: :sociable, dependent: :destroy
accepts_nested_attributes_for :character
has_secure_password
before_validation do
self.create_character unless character
end
before_save do
self.email.downcase!
end
before_create :create_activation_digest
validates :name, presence: true,
length: { maximum: 50 }
VALID_EMAIL_REGEX = /\A[\w+\-.]+#[a-z\d\-]+(?:\.[a-z\d\-]+)*\.[a-z]+\z/i
validates :email, presence: true,
format: { with: VALID_EMAIL_REGEX },
uniqueness: { case_sensitive: false }
validates :password, length: { minimum: 6 }, allow_blank: true
validates :character, presence: true
.
.
end
The Character model:
Character.rb:
class Character < ActiveRecord::Base
belongs_to :sociable, polymorphic: true
has_many :posts, dependent: :destroy
before_save do
self.callsign.downcase!
end
validates :sociable_id, presence: true
VALID_CALLSIGN_REGEX = /\A[a-z\d\-.\_]+\z/i
validates :callsign, presence: true,
length: { maximum: 20 },
format: { with: VALID_CALLSIGN_REGEX },
uniqueness: { case_sensitive: false }
end

Answer 1

It should be:-
test "should be valid" do
assert #user.valid? , "#{#user.errors.messages}"
end