Testing a Non-Rails Application Using Rails
Posted by Mike Blake Sat, 31 Mar 2007 13:11:00 GMT
Rails developers working on enterprise software projects are suprised to discover the lack of automated tests in many mature web applications. As frustrating as this can be, A lack of automated tests is also a tremendous opportunity to
- Learn your non-rails applications underlying database structure.
- Demonstrate to a devlopment team the power of The Rails Framework.
- Encourage automated testing.
Rails may be the quickest path to automate some basic test of your non-rails applications data model. These steps will get you all set up to write your automated tests in Ruby.
- Connect to Your Enterprise Database
- Set DB Conventions
- Safety Net
- Duplicate the Schema
- Extract Development Data
I. Connect to Your Enterprise Database from Rails.
Download and install any os driver, ruby gems, and rails adapters needed to connect to your database:
II. Set Your Existing Database Conventions
Rails Recipes , Recipie #16 can walk you through this very quickly.
Identify any conventions used by your legacy database. Application wide conventions can be set in the config/environment.rb file.
They are specified by calling the appropriate class methods available on ActiveRecord::Base. The methods you need to call depend on how your database is configured:
ActiveRecord::Base.table_name_prefix 'myapp_' ActiveRecord::Base.table_name_suffix = '_def' ActiveRecord::Base.sequence_name = 'dev_company' ActiveRecord::Base.pluralize_table_names = false ActiveRecord::Base.primary_key_prefix_type = :table_name_with_underscore # or :table_name
III. Safety Net
Load the SafetyNet Plugin into your rails app to prevent from destroying your development database.
IV. Duplicate Your Database Schema
OK , with your dev and test development databases set correctly, let’s try duplicting the schema.
rake db:test:clone
If this works right off the bat, you’re one of the lucky ones. Skip to Extracting Development Data
If you recieved errors from the clone command, do steps A through C .
A. You can now correct any errors you may have had by manually modifying schema.rb . See Oracle Errors for some problems I had with the Oracle Database. Since schema.rb is generated, it’s a good idea to rename it when you modify it manually.
B. The clone command above may have started loading data; you need may to purge the test db.
rake db:test:purge
C. Tell rake to load your new schema file by passing the new name, relative to RAILS_ROOT in the SCHEMA environment variable:
rake db:schema:load RAILS_ENV=test SCHEMA=db/oracle_schema.rb
V. Extracting Development Data
Copy the code from Rails Recipe #42: extract_fixtures.rake to your RAILS_ROOT/lib/tasks directory.
TIP: If your develoment database has lots of data, Modify the SQL Select in this code to limit the amount of data you copy using the SQL limit statement:
sql = "SELECT * FROM %s limit = 100"Or for a proprietary database, the equivalent command:
sql = "SELECT * FROM %s WHERE ROWNUM<=100"
Then run
rake extract_fixtures
You’ve made your testbed so you can lie in it.
You now have and exact copy of your development database, and a collection of sample data in Yaml format, and are ready to begin writing some Unit Tests. Stay tuned for some examples. Rail on!
