How do you write a task to run tests in Rails 3?

Question

I would like to write rake tasks to customize tests. For example, to run unit tests, I created a file with the following code and saved it as lib/tasks/test.rake:

task :do_unit_tests do
  cd #{Rails.root} 
  rake test:units
end

Running rake do_unit_tests throws an error: can't convert Hash into String.

Working in Rails 3.0.7 and using built-in unit test framework.

Thanks.

Answer 1

There is no need to cd. You can simply...

task :do_unit_tests do
  Rake::Task['test:units'].invoke
end

But if you really want to cd, that's how you call shell instructions:

task :do_unit_tests do
  sh "cd #{Rails.root}"
  Rake::Task['test:units'].invoke
end

Well, in fact there is a shorter version. The cd instruction have a special alias as Chris mentioned in the other answer, so you can just...

task :do_unit_tests do
  cd Rails.root
  Rake::Task['test:units'].invoke
end

If you want to go further, I recommend Jason Seifer's Rake Tutorial and Martin Fowler's Using the Rake Build Language articles. Both are great.

Answer 2

You're trying to interpolate a value that's not in a string, and you're also treating rake test:units like it were a method call with arguments, which it's not.

Change the cd line so you're calling the method with the value of Rails.root, and change the second line to be a shell instruction.

task :do_unit_tests do
  cd Rails.root
  `rake test:units`
end