rspec users - Mar 2012 - mocking a reference to a polymorphic model?

The basic question: how do you mock a reference to a polymorphic class
in RSpec?  Trying the obvious thing leads to an error of the form:

   undefined method `base_class'' for Post:Class

=== The details:

# file: app/models/relation.rb
class Relation < ActiveRecord::Base
  belongs_to :entity, :polymorphic => true
end

# file: db/xxx_create_relations.rb
class CreateRelations < ActiveRecord::Migration
  def change
    create_table :relations do |t|
      t.references :entity, :polymorphic => true, :null => false
    end
  end
end

# file: spec/models/relation_spec.rb
describe Relation do
  it ''should create instance without error'' do
    post = mock_model("Post")
    lambda { Relation.create!(:entity => @post)}.should_not raise_error
  end
end

=== Running the test:

  1) Relation should create instance without error
     Failure/Error: lambda { Relation.create!(:entity => post)
}.should_not raise_error
       expected no Exception, got #<NoMethodError: undefined method
`base_class'' for Post:Class>
     # ./spec/models/relation_spec.rb:39:in `block (2 levels) in <top
(required)>''

My hunch is that ActiveRecord is calling base_class on the mocked model
(Post) to determine what to stick in the ''entity_type'' column
in the
relations table.  I tried explicitly setting it, as in:

    post = mock_model("Post", :base_class => "Post")

but the error was the same.

For all the reasons that DC espouses, I''d love to mock references to
the
polymorphic models, but I don''t see how to do that.

Any ideas?

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

Are you really sure you need a polymorphic table?

On Thu, Mar 22, 2012 at 12:27, Fearless Fool <lists at ruby-forum.com>
wrote:
> The basic question: how do you mock a reference to a polymorphic class
> in RSpec?  Trying the obvious thing leads to an error of the form:
>
>   undefined method `base_class'' for Post:Class
>
> === The details:
>
> # file: app/models/relation.rb
> class Relation < ActiveRecord::Base
>  belongs_to :entity, :polymorphic => true
> end
>
> # file: db/xxx_create_relations.rb
> class CreateRelations < ActiveRecord::Migration
>  def change
>    create_table :relations do |t|
>      t.references :entity, :polymorphic => true, :null => false
>    end
>  end
> end
>
> # file: spec/models/relation_spec.rb
> describe Relation do
>  it ''should create instance without error'' do
>    post = mock_model("Post")
>    lambda { Relation.create!(:entity => @post)}.should_not raise_error
>  end
> end
>
> === Running the test:
>
>  1) Relation should create instance without error
>     Failure/Error: lambda { Relation.create!(:entity => post)
> }.should_not raise_error
>       expected no Exception, got #<NoMethodError: undefined method
> `base_class'' for Post:Class>
>     # ./spec/models/relation_spec.rb:39:in `block (2 levels) in <top
> (required)>''
>
> My hunch is that ActiveRecord is calling base_class on the mocked model
> (Post) to determine what to stick in the ''entity_type''
column in the
> relations table.  I tried explicitly setting it, as in:
>
>    post = mock_model("Post", :base_class => "Post")
>
> but the error was the same.
>
> For all the reasons that DC espouses, I''d love to mock references
to the
> polymorphic models, but I don''t see how to do that.
>
> Any ideas?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users
>


-- 
*"In matters of style, swim with the current; in matters of principle,
stand like a rock."
Thomas Jefferson
*
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On 22 Mar 2012, at 17:27, Fearless Fool wrote:
> The basic question: how do you mock a reference to a polymorphic class
> in RSpec?  Trying the obvious thing leads to an error of the form:
> 
>   undefined method `base_class'' for Post:Class
> 
> === The details:
> 
> # file: app/models/relation.rb
> class Relation < ActiveRecord::Base
>  belongs_to :entity, :polymorphic => true
> end
> 
> # file: db/xxx_create_relations.rb
> class CreateRelations < ActiveRecord::Migration
>  def change
>    create_table :relations do |t|
>      t.references :entity, :polymorphic => true, :null => false
>    end
>  end
> end
> 
> # file: spec/models/relation_spec.rb
> describe Relation do
>  it ''should create instance without error'' do
>    post = mock_model("Post")
>    lambda { Relation.create!(:entity => @post)}.should_not raise_error
>  end
> end
> 
> === Running the test:
> 
>  1) Relation should create instance without error
>     Failure/Error: lambda { Relation.create!(:entity => post)
> }.should_not raise_error
>       expected no Exception, got #<NoMethodError: undefined method
> `base_class'' for Post:Class>
>     # ./spec/models/relation_spec.rb:39:in `block (2 levels) in <top
> (required)>''
> 
> My hunch is that ActiveRecord is calling base_class on the mocked model
> (Post) to determine what to stick in the ''entity_type''
column in the
> relations table.  I tried explicitly setting it, as in:
> 
>    post = mock_model("Post", :base_class => "Post")
> 
> but the error was the same.
> 
> For all the reasons that DC espouses, I''d love to mock references
to the
> polymorphic models, but I don''t see how to do that.
Can you enumerate those reasons? This doesn''t seem like a good use-case
for mock_model, to me.

cheers,
Matt

--
Freelance programmer & coach
Author, http://pragprog.com/book/hwcuc/the-cucumber-book
Founder, http://www.relishapp.com/
Twitter, https://twitter.com/mattwynne


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