model relationships association with default fabricator

[knwang]

with ActiveRecord, suppose I have a Book model and an Author model and

class Book < ActiveRecord::Base
has_many :authors, through: :books_authors
end

class Author < ActiveRecord::Base
has_many :books, through: :books_authors
end

And the requirement is that a book has to have at least an author, therefore in my book fabricator, I have

Fabricator(:book) do
authors! { Fabricate(:author) }
end

In my cucumber test, I want to be able to say

Given 1 book
And that book has the following author:
| name | John Doe |
.....

Currently if I do this the book will have two authors, one created with the book fabricator and John Doe. I'd like to be able to only have John Doe has the author for the book.

[paulelliott]

You should be doing this the other way around. Always build from the top down.

Given the following author:
| name | John Doe |
And that author has 1 book

[knwang]

I don't think authors are "on top of" books in this example - they "have many through" each other. But agree with you that coming from the other direction would solve this problem.

[paulelliott]

Oh, you are absolutely right. Sorry about that.

The base fabricator should never build things that aren't necessary to persist the object. You should make a :book_with_author fabricator for when you need them together. This will reduce the "magic" in your test suite and make cucumber work a lot better.

[knwang]

Makes a lot of sense. Thanks!