Ruby on rails testing - table X has no column named Y

I am trying to write some basic Rails test code using the default rails testing framework. My application is for a simple forum, where users can post threads, comment etc.

I am trying to test the forum (i.e. a thread) controller, here it is:

forums_controller_test.rb

require 'test_helper'

class ForumsControllerTest < ActionController::TestCase
 test "index should be success" do
  get :index
  assert_response :success
 end
end

I am using fixtures and am following this tutorial: https://www.youtube.com/watch?v=0wIta0fITzc

Here are all my fixture files:

comments.yml

comm_one:
  body: MyText
  forum_id: 1

comm_two:
  body: MyText
  forum_id: 2

forums.yml

for_one:
  title: MyString
  body: MyText
  user_id: 1

for_two:
  title: MyString
  body: MyText
  user_id: 2

users.yml

user_one: 
  user_id: '1'

user_two: 
  user_id: '2'

The issue i am having is that when i run rake in the terminal, I get this error:

Error: ForumsControllerTest#test_index_should_be_success: ActiveRecord::Fixture::FixtureError: table "users" has no column named "user_id".

Not sure if you need to see my migrate files, but if you need any other information, let me know.

I would be grateful for any advice.

Thanks