Rails - Jun 2006 - Dynamic determination of class under test...

I''ve been developing a series of custom assertions for testing my
models and it
looks like I can unify most some of the assertions if I can find a good way to
determine the class under test at run-time.  Now I refactor my test code rather
vigorously so its not as simple as just stripping "Test" off the name
of the
test case class, but I have a few thoughts on a useful convention I can use to
ease it.

Now this is probably more of a (near novice) Ruby question rather than rails,
but I can''t seem to locate the answer -- given a string containing a
class name
is there a way to
  a) check if that class is defined/locatable for inclusion
  b) convert the string to a Class object for the named class

Ie, I''m trying to do:

  def setup
    @klass=class_under_test(self.class)
  end

  protected
  def class_under_test(klass)
    /([A-Z][a-z_]*)Test/.match(klass.to_s)
    $1 # <-----   Now I have a string, not a Class, obviously
       # Of course I need a more complete alogrithm here, but I''d like
to
       # to get the base case working first, do I need to use one of the
       # eval-type functions?
  end

  def assert_attribute_required(field)
    @non_inserted_fixture[field]=nil
    obj = @klass.new(@non_inserted_fixture)   # <---- Now I need a Class
object
    assert_not_valid obj
    assert obj.errors.invalid?(field)
  end

Thank you.

Eric

I am not sure if I get your question right... maybe this is what you need:

require ''set''

def acts_as_test
  TestClasses.get << self
end

class TestClasses
  @@test_classes = Set.new
  def self.get
    @@test_classes
  end
end

class TestMe
  acts_as_test
end

class TestMeToo
  acts_as_test
end
> TestClasses.get.inspect
#<Set: {TestMeToo, TestMe}>


-------- Original-Nachricht --------
Datum: Tue, 13 Jun 2006 10:14:54 -0400
Von: Eric D Nielsen <nielsene@MIT.EDU>
An: rails@lists.rubyonrails.org
Betreff: [Rails] Dynamic determination of class under test...
> I''ve been developing a series of custom assertions for testing my
models
> and it
> looks like I can unify most some of the assertions if I can find a good
> way to
> determine the class under test at run-time.  Now I refactor my test code
> rather
> vigorously so its not as simple as just stripping "Test" off the
name of
> the
> test case class, but I have a few thoughts on a useful convention I can
> use to
> ease it.
> 
> Now this is probably more of a (near novice) Ruby question rather than
> rails,
> but I can''t seem to locate the answer -- given a string containing
a class
> name
> is there a way to
>   a) check if that class is defined/locatable for inclusion
>   b) convert the string to a Class object for the named class
> 
> Ie, I''m trying to do:
> 
>   def setup
>     @klass=class_under_test(self.class)
>   end
> 
>   protected
>   def class_under_test(klass)
>     /([A-Z][a-z_]*)Test/.match(klass.to_s)
>     $1 # <-----   Now I have a string, not a Class, obviously
>        # Of course I need a more complete alogrithm here, but I''d
like to
>        # to get the base case working first, do I need to use one of the
>        # eval-type functions?
>   end
> 
>   def assert_attribute_required(field)
>     @non_inserted_fixture[field]=nil
>     obj = @klass.new(@non_inserted_fixture)   # <---- Now I need a Class
> object
>     assert_not_valid obj
>     assert obj.errors.invalid?(field)
>   end
> 
> Thank you.
> 
> Eric
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

>
>   def assert_attribute_required(field)
>     @non_inserted_fixture[field]=nil
>     obj = @klass.new(@non_inserted_fixture)   # <---- Now I need a Class
> object
>     assert_not_valid obj
>     assert obj.errors.invalid?(field)
>   end

For this part, thanks to ActiveSupport, you would have something like:
...
obj = @klass.constantize.new()
...

That will get you your new class object to work with.


Thank you.
>
> Eric
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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Nick Stuart wrote:
>>
>>   def assert_attribute_required(field)
>>     @non_inserted_fixture[field]=nil
>>     obj = @klass.new(@non_inserted_fixture)   # <---- Now I need a
Class
>> object
>>     assert_not_valid obj
>>     assert obj.errors.invalid?(field)
>>   end
> 
> 
> For this part, thanks to ActiveSupport, you would have something like:
> ...
> obj = @klass.constantize.new()
> ...
Thank you, that was one half of what I was looking for and I''m
positively I can figure out the rest now that the base case works.

Eric

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