How do I force RAILS_ENV in a rake task?

Question

I have this little rake task:

namespace :db do 
  namespace :test do 
    task :reset do 
      ENV['RAILS_ENV'] = "test" 
      Rake::Task['db:drop'].invoke
      Rake::Task['db:create'].invoke
      Rake::Task['db:migrate'].invoke
    end
  end
end

Now, when I execute, it will ignore the RAILS_ENV I tried to hard-code. How do I make this task work as expected

Answer

For this particular task, you only need to change the DB connection, so as Adam pointed out, you can do this:

namespace :db do 
  namespace :test do 
    task :reset do 
      ActiveRecord::Base.establish_connection('test')
      Rake::Task['db:drop'].invoke
      Rake::Task['db:create'].invoke
      Rake::Task['db:migrate'].invoke
      ActiveRecord::Base.establish_connection(ENV['RAILS_ENV'])  #Make sure you don't have side-effects!
    end
  end
end

If your task is more complicated, and you need other aspects of ENV, you are safest spawning a new rake process:

namespace :db do 
  namespace :test do 
    task :reset do 
      system("rake db:drop RAILS_ENV=test")
      system("rake db:create RAILS_ENV=test")
      system("rake db:migrate RAILS_ENV=test")
    end
  end
end

or

namespace :db do 
  namespace :test do 
    task :reset do 
      if (ENV['RAILS_ENV'] == "test")
        Rake::Task['db:drop'].invoke
        Rake::Task['db:create'].invoke
        Rake::Task['db:migrate'].invoke
      else
        system("rake db:test:reset RAILS_ENV=test")
      end
    end
  end
end