rails minitest is driving me insane with PG::UniqueViolation errors - ruby-on-rails

Question

Half of the time I'll be able to make my tests run. The other half they fail because of a uniqueness violation, the source of which I am unable to locate. Right now I am in the latter half. My error is this:
ItemTest#test_valid_setup:
ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR: duplicate key value violates unique constraint "index_blobs_on_user_id_and_item_id"
DETAIL: Key (user_id, item_id)=(1, 1) already exists.
: INSERT INTO "blobs" ("user_id", "item_id", "amount", "active", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id"
test/models/item_test.rb:15:in `setup'
I have a factories.rb:
FactoryBot.define do
factory :user, aliases: [:owner] do
email "test#test.com"
username "test"
end
factory :item do
owner
image { loads file etc... }
price 100
...
end
factory :blob, aliases: [:wanted, :collateral] do
user
item
amount 0
active true
end
end
My item_test.rb
require 'test_helper'
require 'support/database_cleaner'
class ItemTest < Minitest::Test
def setup
DatabaseCleaner.start
#create users
#user1 = FactoryBot.create(:user, email: "a#pear.com", username: "barnyard")
#user2 = FactoryBot.create(:user, email: "bo#ichi.com", username: "ponygrl")
#user3 = FactoryBot.create(:user, email: "ho#ho.com", username: "hon")
#create items
#item1 = FactoryBot.create(:item, owner: #user1)
#item2 = FactoryBot.create(:item, owner: #user2, price: 101)
#item3 = FactoryBot.create(:item, owner: #user3, price: 102)
#create blobs
#blob1 = FactoryBot.create(:blob, user: #user1, item: #item1, amount: #item1.price, active: false)
#blob2 = FactoryBot.create(:blob, user: #user2, item: #item2, amount: #item2.price, active: false)
#blob3 = FactoryBot.create(:blob, user: #user3, item: #item3, amount: #item3.price, active: false)
end
def teardown
DatabaseCleaner.clean
end
end
And then an item.rb
class Item < ApplicationRecord
after_create :create_blobs
private
def create_blobs
blob = Blob.new(user_id: self.owner.id, item_id: self.id, amount: self.price)
blob.save
end
end
A little background: A User creates an Item which in turn creates a Blob in an after_create with an amount parameter set to the value of Item's price. I cannot find out how to run an after_create in minitest, so I mocked up the Blob data in setup to inherit from an attribute of Item.
I can see that the error comes from line 15 of item_test.rb, but I'm not understanding why. I'm creating the Users, then the Items, and then ERROR the Blobs. I understand the why (I have a db level uniqueness constraint on a combination of user and item) but not the how (because from what I see, I haven't created those Blobs - there's no after_create called on Item when they're created in test), and I suspect that it has to do with the way I'm writing this.
It seems natural to me to conclude that DatabaseCleaner.start and DatabaseCleaner.clean both start and clean up old test data when the test is run and concluded, but this is obviously not the case. I started using it specifically to avoid this problem, which I was having previously. So I db:drop db:create, and db:schema:load, but once again, I have the same issue. And if it's not that, it's a uniqueness violation on a username, an email, etc......long story short, what is going on with that error?
Sorry if this is so confusing.
Edit: If I uncomment the after_create and replace all method references to the blob object created through that callback with blobs created in my test setup, the tests pass. But I really don't like doing that.

Answer 1

Either uncomment the after_create and reference the test objects, or remove the test objects and reference each blob by writing a method that returns the blob owned_by user and item, so that you can write #item.blob, and have it return the relevant blob.