Testing associations with rspec: Category does not have a post_id foreign key

Question

I'm trying to test some associations with RSpec but I get these failures:

Category 
   Failure/Error: it {should belong_to :post}
   Expected Category to have a belongs_to association called post (Category does not have  a post_id foreign key.)
 # ./spec/models/category_spec.rb:7:in `block (2 levels) in <top (required)>'

Post 
 Failure/Error: it {should have_one (:category)}
   Expected Post to have a has_one association called category (Category does not have a post_id foreign key.)
 # ./spec/models/post_spec.rb:8:in `block (2 levels) in <top (required)>'

Here's my model:

class Post < ActiveRecord::Base
  has_one :category
  validates_presence_of :author, :category, :post
end

class Category < ActiveRecord::Base
  belongs_to :post
  validates_presence_of :name
end

and my tests:

require 'spec_helper'

describe Post do
  it {should validate_presence_of(:author)}
  it {should validate_presence_of(:post)}
  it {should validate_presence_of(:cathegory)}
  it {should have_one (:category)}  
end

describe Category do
  it {should validate_presence_of :name}
  it {should belong_to :post}
end

and my scheme

 ActiveRecord::Schema.define(:version => 20121118131441) do

   create_table "categories", :force => true do |t|
     t.string   "name"
     t.datetime "created_at", :null => false
     t.datetime "updated_at", :null => false
     t.integer  "post_id"
   end

   create_table "posts", :force => true do |t|
     t.string   "author"
     t.string   "cathegory"
     t.text     "post"
     t.datetime "created_at",  :null => false
     t.datetime "updated_at",  :null => false
     t.integer  "category_id"
   end

end

Does anybody have any idea what's going on?

Answer 1

Without seeing your schema, it looks like your database tables are missing the foreign key columns. Creating a migration that adds the following should fix it:

add_column :categories, :post_id
add_column :posts, :category_id

Update

As I said in my comment below, also make sure you run rake db:test:prepare to ensure your test database has the most recent schema.

Answer 2

I had recently the same issue, but my schema was fine, the problem was that I were also specifying the inverse_of and it was wrongly spelled. It seems that in that case you also get this error.