Carrierwave extension_white_list not passing after fixture file_upload a fixture image. What is happening?

I put a file into my spec/support/images/picture.jpg. When I saved it into there, I changed the file extension of the file. Is that what is wrong?

This is my error, and I think it's because it's not getting passed the extension_white_list method in the uploader:

pry(#<StoryMainImageUploader>)> exit

  2) Api::Recipes::RecipeToolsController GET index when given recipe params should have a description attribute for each recipe tool
     Failure/Error: rt.story = create(:story, :with_products) if rt.story.blank?

     ActiveRecord::RecordInvalid:
       Validation failed: Main image is invalid. Allowed file types are jpg, jpeg, gif, and png

This is my story.rb file:

  mount_uploader :main_image, StoryMainImageUploader

This is my factory:

factory :story do
    title       'Pizza For Dummies'
    description 'Are you dumb? Do you like pizza? Then this this is the story for you!'
    status      Story::Status::INCOMPLETE
    main_image { Rack::Test::UploadedFile.new(File.join(Rails.root, 'spec', 'support', 'images', 'blueaproncarrierimage.jpg')) }
     ....


  end
end

This is my uploader:

# encoding: utf-8
require 'carrierwave/processing/mime_types'

class StoryMainImageUploader < CarrierWave::Uploader::Base
  include CarrierWaveDirect::Uploader
  include CarrierWave::RMagick
  include CarrierWave::MimeTypes
  include S3DirectUploader

  process :set_content_type

  def store_dir
    "stories/#{model.id}/main_images"
  end

  def extension_white_list
    binding.pry
    %w(jpg jpeg gif png)
  end

  version :medium do
    process :resize_to_limit => [800, 800]
  end

  version :thumb do
    process :resize_to_limit => [200, 200]
  end
end

This is my s3directuploader:

module S3DirectUploader
  attr_accessor :process_url

  def bucket_url
    "http://ift.tt/1XvEoY9}"
  end

  def bucket
    AppConfigs['fog']['fog_directory']
  end

  def policy
    Base64.encode64(policy_data.to_json).gsub("\n", '')
  end

  def policy_data
    {
      expiration: 10.hours.from_now.utc.iso8601,
      conditions: ...
    }
  end

  def signature
    Base64.encode64(
      OpenSSL::HMAC.digest(
        OpenSSL::Digest.new('sha1'),
        AppConfigs['fog']['fog_credentials']['aws_secret_access_key'], policy
      )
    ).gsub("\n", '')
  end

  def acl
    'public-read'
  end

  def to_hash
    {
      key: key,
      bucket_url: bucket_url,
      policy: policy,
      signature: signature,
      acl: acl,
      aws_access_key_id: aws_access_key_id,
      process_url: process_url
    }
  end
end

Any idea what is going on and what might the problem be?