Rails - May 2006 - Agile Web Dev unit test fails with fixture instance variable

I''m following Agile Edition 1. On page 148 it suggests using instance 
variables named after the fixture, for example:

assert_equal @version_control_book.id, @product.id

When I introduce this type of instance variable into my test, I get the 
following error:

  1) Error:
test_not_owner(GroupTest):
RuntimeError: Called id for nil, which would mistakenly be 4 -- if you 
really wanted the id of nil, use object_id
    test/unit/group_test.rb:8:in `setup_without_fixtures''
   
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.2/lib/active_record/fixtures.rb:548:in
`setup''

Line 8:

@group = Group.find(@alice_group.id)

where alice_group is my Group fixture.

I know there are a few issues with the testing section of the Agile book 
- have I just hit one?

thanks
Lindsay.


-- 
Posted via http://www.ruby-forum.com/.

On May 22, 2006, at 6:53 AM, Lindsay Boyd wrote:
> I''m following Agile Edition 1. On page 148 it suggests using
instance
> variables named after the fixture, for example:
>
> assert_equal @version_control_book.id, @product.id
>
> When I introduce this type of instance variable into my test, I get  
> the
> following error:
>
>   1) Error:
> test_not_owner(GroupTest):
> RuntimeError: Called id for nil, which would mistakenly be 4 -- if you
> really wanted the id of nil, use object_id
>     test/unit/group_test.rb:8:in `setup_without_fixtures''
>     /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.2/lib/ 
> active_record/fixtures.rb:548:in
> `setup''
>
> Line 8:
>
> @group = Group.find(@alice_group.id)
>
> where alice_group is my Group fixture.
>
> I know there are a few issues with the testing section of the Agile  
> book
> - have I just hit one?
Yes, this is an artifact of the book coming out while Rails was still  
in flux. The right way to reference a fixture is to use alternative  
syntax like so: fixture_name(:fixture_element)

Using the depot application as the example, the book uses the old  
syntax (like on page 148). Instead of @version_control_book.id the  
syntax should be products(:version_control_book).id.

In your specific example, the code should probably be groups 
(:alice_group).id (assuming you have a line "fixtures :groups" in  
your test).

Hope this helped.

cr