[rspec-users] How to modify database inside a transaction in before(:all)?

Rodrigo Rosenfeld Rosas lbocseg at yahoo.com.br
Tue Apr 24 02:22:24 UTC 2012


Em 23-04-2012 20:04, David Chelimsky escreveu:
> On Mon, Apr 23, 2012 at 5:39 PM, Rodrigo Rosenfeld Rosas
> <rr.rosas at gmail.com>  wrote:
>> I have a set of examples that should run with a specific set of records in
>> the database.
>>
>> Since setting those records is an expensive operation I'd like to perform it
>> just once per context.
>>
>> For example:
>>
>> context 'sample tree' do
>>      before(:all) { create_tree_records }
>>
>>      example ...
>> end
>>
>> The problem with this is that while before(:each) and the examples will run
>> in a transaction that will be rolled back at the end of each example, that
>> won't happen to the records created/modified by the before(:all) block.
>>
>> It seems my database vendor (PostgreSQL) supports nested transactions
>> (savepoints):
>>
>> http://www.postgresql.org/about/
>>
>> I should also notice that I'm using Sequel and it seems that transactions
>> are reentrant in Sequel:
>>
>> http://cheat.errtheblog.com/s/sequel/
>>
>> Database#transaction is re-entrant:
>>
>>    DB.transaction do # BEGIN issued only here
>>      DB.transaction
>>        dataset<<  {:first_name =>  'Inigo', :last_name =>  'Montoya'}
>>      end
>> end # COMMIT issued only here
>>
>> So, this logic wouldn't work for me. I need a save point in a before(:all),
>> so that I'd restore it on a before(:each).
>>
>> Is there any recommendation to make this work in my specs?
> Nothing built into RSpec now, but you could disable the Rails
> transaction management and use DatabaseCleaner on your own.

Actually I'm not using the Rails transaction management anymore since I 
moved all my models to Sequel::Model. I've created a section in my last 
article on how to setup Sequel, Rails and RSpec. Please check the RSpec 
section:

http://rosenfeld.herokuapp.com/en/articles/2012-04-18-getting-started-with-sequel-in-rails

The issue with using DatabaseCleaner is that it doesn't support nested 
transactions too. And I don't want to use the truncate strategy as there 
are some tables that shouldn't be cleared.

> This is currently being discussed in
> https://github.com/rspec/rspec-rails/issues/496 as well. Feel free to
> join that convo.

I don't know if this is possible to accomplish with all supported 
databases. Maybe there is a simpler approach for PostgreSQL by using 
savepoints. I'll make some experiments similar to the approach I've used 
in my article to create those savepoints.

I'd just like to know if there was something already done following this 
idea, but if there isn't, I guess I'll have to do it myself :(

Thank you very much for your (always) fast response :)

Cheers,
Rodrigo.
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