08 Jul 2006

validating Rails association

rails, ruby on rails, software posted by manik

Should ActiveRecord add validations based on associations defined in the models?

class User < ActiveRecord::Base
  has_many :posts
end 

class Post < ActiveRecord::Base
  belongs_to :user
end

If i create an instance of a post with a user_id that does not exist in the Users table, I wish ActiveRecord threw up a validation error on saving this instance of post.
It does not do so by default, so here are the validations that I add to my models to implement this.

class User < ActiveRecord::Base
  has_many :posts
end 

class Post < ActiveRecord::Base
  belongs_to :user
  validates_associated :user
  validates_presence_of :user
end

Now if I try and save a post without a user_id or with a user_id that is not found in the Users table, an exception is thrown.

Till now I always use to create foreign keys in my database, as a safety net. So that the db throws an error if my data is not consistent.
After adding these validations, I hope not to have foreign keys in the database anymore.

26 Apr 2006

testing rails application

ruby on rails, software, testing posted by manik

Have been busy recently comparing Rails 1.1’s integration testing and WATIR and selenium for end-to-end testing a rails application.

The testing scenario is that the webserver is running on a remote Linux box in US, to which we have ssh access.
And we are testing the application from India. So we cannot run the browser on that machine.

We are writing test cases for various parts of the application using each of these tools and then we would compare notes.

A few things however are clear rightaway.

WATIR will test only for IE on windows. Firefox support for watir called firewatir is being built, and is not robust as of now. Also we might need different sets of test scripts for firefox and IE.

Selenium is the easiest to get started in the BrowseBot FITRunner mode; haven’t tried the “driven” mode yet. FIT mode would not allow us to verify values on the screen against those in the db… but then probably those tests should go into the “controller testing”(functional testing) and not be at this level. When we want to test against db for multiple controllers then rails’ integration testing is the probably the best way.

Running selenium in “driven” mode will take some research, for which i have not been able to spare time.

WATIR requires ruby and watir gems to be installed on the client computer. Hence if we want to share UI tests with our non-technical client, Selenium is better since it requires no installation.

From the aspect of writing test cases, WATIR is better than selenium’s FIT mode. Selenium test cases need to be written in html. And there is no control flow in the selenium core, though there is a user contributed library for this.

For certain kind of testing, such as against db values and checking values in session, Rails functional tests and integration tests are great.

Will share more experiences on this when we are through with the exercise.

How has your experience with these tools been?

***********************************
Received this profound quotation in my email today.

“The greatest good you can do for another is not just to share your riches, but to reveal to him his own.”
Benjamin Disraeli
1804-1881, Former British Prime Minister
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