A Single Programmer's Blog

Just got bitten by a bug. In a model, I was doing:

1 self.unit_price = self.product.current_price(Date.today) \

2   if self.unit_price.cents.blank?

After upgrading to Rails 0.14.3, I found some failures in my tests. About 30 minutes of sleuthing around, and I found my bug to be with the new object.blank? behavior.

Some console code to “prove” it:

 1 $ ruby script\console

 2 Loading development environment.

 3 >> 0.blank?

 4 => true

 5 >> exit

 6 

 7 $ svn up vendor\rails

 8 …

 9  U   vendor\rails

10 Updated external to revision 2932.

11 

12 $ ruby script\console

13 Loading development environment.

14 >> 0.blank?

15 => false

So, I rewrote my code to now do:

1 self.unit_price = self.product.current_price(Date.today) \

2   if 0 == self.unit_price.cents

Again, this shows how a good set of unit and functional tests can help prevent problems before they hit you.

After updating my externals to Rails 0.14.1, I ran into a few snags. First one is a difference in the handling of boolean attributes between both versions. I had the following assertion:

1 class EstimateTest < Test::Unit::TestCase

2   def test_converts_base_information_to_quote

3     # …

4     assert_equal e.pst_active, q.pst_active, ‘copied pst active’

5   end

6 end

q is an instance of Quote, and e is an instance of Estimate. In both cases, pst_active determines if the provincial tax is active. It is a boolean attribute, but I had forgotten to use the attr_name? form. In 0.13.1, this worked, but with 0.14.1, it failed with the following:

1   1) Failure:

2 test_converts_base_information_to_quote(EstimateTest) [./test/unit/estimate_test.rb:493]:

3 copied pst active.

4 <1> expected but was

5 <true>.

When I switched both calls to pst_active to the boolean form, the assertion passed again.

Next, I had 44 failures in my functionnal tests:

1  44) Error:

2 test_destroyed_pictures_dont_appear_in_the_slideshow(WelcomeControllerTest):

3 TypeError: cannot convert Symbol into String

4     D:/rails-app/config/../lib/productize.rb:38:in `+’

5     D:/rails-app/config/../lib/productize.rb:38:in `full_template_path’

This application makes use of the Rails Product Generator. Notice the bug is in lib/productize.rb, and not my code per se. Line 38 of lib/productize.rb looks like this:

1 site_specific_path = File.join(SITE_ROOT, ‘app’, ‘views’, template_path + ‘.’ + extension)

I corrected the error by simply calling to_s on both template_path and extension.

After that, my tests ran perfectly ! Shows how important it is to have even a minimal test suite.