Rspec unit test fails sometimes (validation race condition)

rubyonrails-talk
1

I have code similar to this:

class Post   has_many :comments end

class Comment   belongs_to :post   validate :must_not_exceed_ten

  def must_not_exceed_ten     errors.add_to_base('Too many comments') unless post.comments.length < 10   end end

and in the specs (Rspec + machinist):

post = Post.make 9.times { Comment.make(:post => post) } comment = Comment.new(:post => post) comment.save.should be_false

The weird thing about it is that it fails sometimes! Especially if I run the whole test suite with rake command (the probability is higher). When I check in the console post indeed has 11 comments. Can somebody give me a reasonable explanation why this is happening? Is this some sort of a race condition that I'm missing?

2

In the specs it is actually 10.times instead of 9.

Milan Dobrota wrote:

3

Milan Dobrota wrote:

In the specs it is actually 10.times instead of 9.

Milan Dobrota wrote:

post = Post.make 9.times { Comment.make(:post => post) } comment = Comment.new(:post => post) comment.save.should be_false

Well, there's your problem, then -- you've already made your 10th comment!

BTW, you should consider comments.count instead of .length -- let the DB do the counting.

Best,

4

No because validations happen before the object is saved. Validation will pass and the object will get saved properly. Well... sometimes. Sometimes not.

Marnen Laibow-Koser wrote: