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Jeroen van Dijk

2008-Oct-08 11:01 UTC

[rspec-users] Refactoring and using each

Hi all,

I''m new to this list and new to RSpec so I have been trying out RSpec
the
last couple of days and I find it very a natural way of testing. So first of
all thanks for providing this framework.

Now, I have written some tests for my controllers and models and I saw
myself writing similar code, so I began refactoring and came up with the
following issue.

Here is a simple example of what I first wrote:

describe Example do

  it "should not be valid without attribute1" do
    Example.new(:attribute2 => "2").should_not be_valid
  end

  it "should not be valid without attribute2" do
    Example.new(:attribute1 => "1").should_not be_valid
  end
end

Which I rewrote into another working test:

######
module ExampleSpecHelper
  def required_valid_attributes
    {:attribute1 => "1", :attribute2 => "2"}
  end
end

describe Example do
   include ExampleSpecHelper
  [:attribute1, :attribute2].each do |attribute|
  before(:all) do
    @model_with_one_missing_attribute
TextMessage.new(required_valid_attributes.except(attribute))
  end

  it "should not be valid without #{attribute}" do
    @model_with_one_missing_attribute.should_not be_valid
  end
end
#####

In this example in you might not see difference in lines of code, but
imagine you would have 10 attributes and 10 more tests for each attribute..
Now I rewrote this I was still not satisfied because I thought I would like
to use this same  approach for several models with different attributes
while keeping the logic of this test in one place. Unfortunately, I
didn''t
come that far because of this:

#this works:
describe Example do
include ExampleSpecHelper
  required_attributes = [:attribute1, :attribute2]
  required_attributes.each do |attribute|
  before(:all) do
    @model_with_one_missing_attribute
TextMessage.new(required_valid_attributes.except(attribute))
  end

  it "should not be valid without #{attribute}" do
    @model_with_one_missing_attribute.should_not be_valid
  end
end

#However this which eventually will be more DRY, but does for some reason
not work?!
module ExampleSpecHelper
  ...
  def required_attributes
    [:attribute1, :attribute2]
  end
...
end

describe Example do
include ExampleSpecHelper
  required_attributes.each do |attribute|
  before(:all) do
    @model_with_one_missing_attribute
TextMessage.new(required_valid_attributes.except(attribute))
  end

  it "should not be valid without #{attribute}" do
    @model_with_one_missing_attribute.should_not be_valid
  end
end


############

I don''t understand why it does not work. In the last example
required_attributes is nil while the other methods from the helper module
such as ''required_valid_attributes'' are available on an even
lower level.
Why? I hope you understand why I''m trying to refactor it like this. If
I can
do this I only need to define the required attributes for each model and use
it_should_behave_like "an AR model" to keep it DRY.

Hope someone can clarify this and that I haven''t done something stupid!
Thanks!

Cheers,

Jeroen
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David Chelimsky

2008-Oct-08 13:02 UTC

head link

[rspec-users] Refactoring and using each

On Wed, Oct 8, 2008 at 6:01 AM, Jeroen van Dijk
<jeroentjevandijk at gmail.com> wrote:> Hi all,
>
> I''m new to this list and new to RSpec so I have been trying out
RSpec the
> last couple of days and I find it very a natural way of testing. So first
of
> all thanks for providing this framework.
>
> Now, I have written some tests for my controllers and models and I saw
> myself writing similar code, so I began refactoring and came up with the
> following issue.
>
> Here is a simple example of what I first wrote:
>
> describe Example do
>
>   it "should not be valid without attribute1" do
>     Example.new(:attribute2 => "2").should_not be_valid
>   end
>
>   it "should not be valid without attribute2" do
>     Example.new(:attribute1 => "1").should_not be_valid
>   end
> end
>
> Which I rewrote into another working test:
>
> ######
> module ExampleSpecHelper
>   def required_valid_attributes
>     {:attribute1 => "1", :attribute2 => "2"}
>   end
> end
>
> describe Example do
>    include ExampleSpecHelper
>   [:attribute1, :attribute2].each do |attribute|
>   before(:all) do
>     @model_with_one_missing_attribute >
TextMessage.new(required_valid_attributes.except(attribute))
>   end
>
>   it "should not be valid without #{attribute}" do
>     @model_with_one_missing_attribute.should_not be_valid
>   end
> end
> #####
>
> In this example in you might not see difference in lines of code, but
> imagine you would have 10 attributes and 10 more tests for each attribute..
> Now I rewrote this I was still not satisfied because I thought I would like
> to use this same  approach for several models with different attributes
> while keeping the logic of this test in one place. Unfortunately, I
didn''t
> come that far because of this:
>
> #this works:
> describe Example do
> include ExampleSpecHelper
>   required_attributes = [:attribute1, :attribute2]
>   required_attributes.each do |attribute|
>   before(:all) do
>     @model_with_one_missing_attribute >
TextMessage.new(required_valid_attributes.except(attribute))
>   end
>
>   it "should not be valid without #{attribute}" do
>     @model_with_one_missing_attribute.should_not be_valid
>   end
> end
>
> #However this which eventually will be more DRY, but does for some reason
> not work?!
> module ExampleSpecHelper
>   ...
>   def required_attributes
>     [:attribute1, :attribute2]
>   end
> ...
> end
>
> describe Example do
> include ExampleSpecHelper
>   required_attributes.each do |attribute|
>   before(:all) do
>     @model_with_one_missing_attribute >
TextMessage.new(required_valid_attributes.except(attribute))
>   end
>
>   it "should not be valid without #{attribute}" do
>     @model_with_one_missing_attribute.should_not be_valid
>   end
> end
>
>
> ############
>
> I don''t understand why it does not work. In the last example
> required_attributes is nil while the other methods from the helper module
> such as ''required_valid_attributes'' are available on an
even lower level.
> Why? I hope you understand why I''m trying to refactor it like
this. If I can
> do this I only need to define the required attributes for each model and
use
> it_should_behave_like "an AR model" to keep it DRY.
>
> Hope someone can clarify this and that I haven''t done something
stupid!
There are a couple of problems with this approach. First of all,
before(:all) runs only once per group, whereas before(:each) runs
repeatedly before(:each) example. This means that whatever gets
created before(:all) is shared across examples, whereas what is
created in before(:each) is not.

Generally speaking, you should avoid before(:all) except for setting
up expensive things like database connections.

Also, you can write as many different before(:each) or before(:all)
blocks and they will all be run, so this:

[:attribute1, :attribute2].each do |attribute|
  before(:all) do
    @model_with_one_missing_attribute
TextMessage.new(required_valid_attributes.except(attribute))
  end
end

is the equivalent of this:

before(:all) do
  @model_with_one_missing_attribute
TextMessage.new(required_valid_attributes.except(:attribute1))
end

before(:all) do
  @model_with_one_missing_attribute
TextMessage.new(required_valid_attributes.except(:attribute2))
end

They get run in order, one time each, resulting in
@model_with_one_missing_attribute missing :attribute2 for every time
the example gets run. The same problem would happen with before(:each)
in this case.

What might work here would be something like this:

describe "this model" do
  def valid_attributes
    {:first => ''valid'', :second =>
''valid''}
  end

  valid_attributes.keys.each do |attribute|
    it "should require #{attribute}
      @model.new(valid_attributes.dup.delete(attribute)).should_not be_valid
    end
  end
end

I''ve seen a number of variations like this posted to this list, so you
might want to search the archives for ''model validation''.

Also, there are a few plugins that offer ways to do this already:

http://github.com/joshknowles/rspec-on-rails-matchers
http://github.com/pelargir/rspec_validation_expectations

I''m sure there are others.

HTH,
Cheers,
David
> Thanks!
>
> Cheers,
>
> Jeroen

Nick Hoffman

2008-Oct-09 19:27 UTC

head link

[rspec-users] Refactoring and using each

On 2008-10-08, at 07:01, Jeroen van Dijk wrote:> Hi all,
>
> I''m new to this list and new to RSpec so I have been trying out  
> RSpec the last couple of days and I find it very a natural way of  
> testing. So first of all thanks for providing this framework.
>
> Now, I have written some tests for my controllers and models and I  
> saw myself writing similar code, so I began refactoring and came up  
> with the following issue.
>
> Here is a simple example of what I first wrote:
>
> describe Example do
>
>   it "should not be valid without attribute1" do
>     Example.new(:attribute2 => "2").should_not be_valid
>   end
>
>   it "should not be valid without attribute2" do
>     Example.new(:attribute1 => "1").should_not be_valid
>   end
> end
>
> Which I rewrote into another working test:
>
> ######
> module ExampleSpecHelper
>   def required_valid_attributes
>     {:attribute1 => "1", :attribute2 => "2"}
>   end
> end
>
> describe Example do
>    include ExampleSpecHelper
>   [:attribute1, :attribute2].each do |attribute|
>   before(:all) do
>     @model_with_one_missing_attribute =  
> TextMessage.new(required_valid_attributes.except(attribute))
>   end
>
>   it "should not be valid without #{attribute}" do
>     @model_with_one_missing_attribute.should_not be_valid
>   end
> end
> #####
>
> In this example in you might not see difference in lines of code,  
> but imagine you would have 10 attributes and 10 more tests for each  
> attribute.. Now I rewrote this I was still not satisfied because I  
> thought I would like to use this same  approach for several models  
> with different attributes while keeping the logic of this test in  
> one place. Unfortunately, I didn''t come that far because of this:
>
> #this works:
> describe Example do
> include ExampleSpecHelper
>   required_attributes = [:attribute1, :attribute2]
>   required_attributes.each do |attribute|
>   before(:all) do
>     @model_with_one_missing_attribute =  
> TextMessage.new(required_valid_attributes.except(attribute))
>   end
>
>   it "should not be valid without #{attribute}" do
>     @model_with_one_missing_attribute.should_not be_valid
>   end
> end
>
> #However this which eventually will be more DRY, but does for some  
> reason not work?!
> module ExampleSpecHelper
>   ...
>   def required_attributes
>     [:attribute1, :attribute2]
>   end
> ...
> end
>
> describe Example do
> include ExampleSpecHelper
>   required_attributes.each do |attribute|
>   before(:all) do
>     @model_with_one_missing_attribute =  
> TextMessage.new(required_valid_attributes.except(attribute))
>   end
>
>   it "should not be valid without #{attribute}" do
>     @model_with_one_missing_attribute.should_not be_valid
>   end
> end
>
>
> ############
>
> I don''t understand why it does not work. In the last example  
> required_attributes is nil while the other methods from the helper  
> module such as ''required_valid_attributes'' are available
on an even
> lower level. Why? I hope you understand why I''m trying to refactor
> it like this. If I can do this I only need to define the required  
> attributes for each model and use it_should_behave_like "an AR  
> model" to keep it DRY.
>
> Hope someone can clarify this and that I haven''t done something  
> stupid! Thanks!
>
> Cheers,
>
> Jeroen
Hi Jeroen. As I was getting into RSpec and writing specs for my  
various models, I too found that my code could be a lot DRYer. I ended  
up writing a module that generates specs for my model attributes. I''ve
put it up on GitHub, along with full, lengthy example of how to use  
it. Have a look:
   http://github.com/nickhoffman/modelspeccer/

Cheers,
Nick

rspec users - Oct 2008 - Refactoring and using each

[rspec-users] Refactoring and using each

[rspec-users] Refactoring and using each

[rspec-users] Refactoring and using each