Allow to pass a lambda function to sequence initial value

[javierav]

This merge allow us to pass a lambda function as the initial value of sequence. This lambda will be called the first time that is used (lazy load). For example:

factory :user do
  sequence(:email, -> { User.count }) { |n| "person#{n}@example.com" }
end

[composerinteralia]

Thanks for the PR. This is an interesting idea. Can you provide some more detail on when this would be useful? For the -> { User.count } example you gave, is there a reason you need to start the sequence at that particular value vs. starting either at 1 or, if there are already some user fixtures loaded, at some arbitrary number like 1000?

[composerinteralia]

Calling the block again when we rewind means that rewinding will not bring us back to the value we started at. This sort of goes against why we introduced the feature to rewind sequences - it was for people who were relying on specific ids in their tests for one reason or another.

If we go forward with this feature, I think we will need some additional test coverage around how this works with rewinding sequences.

[javierav]

Thanks you @composerinteralia for your comments. I review them ASAP, I do not have time these days....

[composerinteralia]

Thanks for the response. ASAP is not necessary at all. This PR isn't going anywhere, so please take your time.

[entcheva]

Hi @javierav - are you still interested in working on this, or should we close this PR? If you're still planning on working on this within the next few months, we'll keep it open, but if you no longer have the time to commit we can close it. Thank you!

[entcheva]

Hi @javierav - since there hasn't been activity on this PR since August, I'm going to close it. If you find you have time in the future to revisit, please feel free to reopen or open a new PR!

[aalvarado]

You can change the existing sequence in the registry itself:

FactoryGirl.sequences.find(:email).instance_variable_set(:@value, FactoryGirl::Sequence::EnumeratorAdapter.new(1000))