writing tests for modules in lib folder - ruby-on-rails-3

Question

I want to write unit tests for a module file I created and put it in lib directory. Under test/unit directory, I have created a mylib_test.rb file. In the file I have required mylib. When I run rake test:units it gives a const_missing: uninitialized constant mylib::constantname error. I'm thinking that this is because it is not loading the rails environment since the constant is defined in one of the initializers file. I'm I correct? How do I get it to work? What is the best way to write unit tests for modules?
I'm using rails 3.1.3 and the model works perfectly when I run the application both from terminal and from a browser.

Answer 1

I just ran into this as well. There are (at least?) 2 possible problems:
Your module is not in the autoload path
Look in config/application.rb for this line:
config.autoload_paths += %W(#{config.root}/extras)
If it's commented, uncomment it. This line will turn on autoloading for all files inside extras, and all files in subdirectories of extras, too. It's probably safest to move your modules into extras, but if you really want to leave them in lib, change the line to be:
config.autoload_paths += %W(#{config.root}/extras #{config.root}/lib)
Your module is in the autoload path, but not named the way Rails expects
(see this: Rails 2.3.5: How does one access code inside of lib/directory/file.rb?)
By convention, Rails wants the name of your module to match the directory hierarchy and the filename. So the file extras/mylib.rb would be expected to contain
module Mylib # not MyLib or My_lib
...
end
This works for subdirectories as well, so a file extras/mydir/mylib.rb should contain:
module Mydir
module Mylib # or class Mylib
...
end
end
This naming convention is the same as what Rails expects for controllers and models. Underscores in the filename turn into a camelcase class/module name. A file called my_lib.rb would be expected to have a module MyLib in it (but not Mylib).
NOTE that autoload does not mean that the module is automatically loaded at startup; rather, it's automatically loaded when it's first used. So even if you have some code like puts "hi from mylib" at the top of your mylib.rb file, you won't see that print until your code uses Mylib somewhere.
Finally, if you really want your modules to load at startup, go create a file called config/initializers/force_load_libraries.rb and put this in there:
Dir.glob("#{Rails.root}/extras/force_load/*.rb").each { |f| require f }
Now go put your libs in extras/force_load and they should load when Rails starts up.

Answer 2

I finally realized what was wrong. In my test files, I was including my modules from the lib directory, Instead of reopening the module and put the test files in the the module. After doing that rake test:units works perfectly. Test files should remain in test/unit directory