Why do test:units and test:functionals insist on running in development environment?

To give you a full answer I would have to take a look at the code, but I'll try to give you some clues that might be helpful.

First of all rake test and all the other variants (test:units, test:functionals etc.) work as follows

1. Rake process is invoked and task test is executed in the current environment (which is development by default), that's why development.rb is always read.
2. The Rake task invokes the test loader in a separate child process (you can verify this with ps or pstree), this is where the test_helper.rb is sourced and environment is set to test.

When you run ruby test/unit/my_test.rb the first step is skipped, so it looks like the problem lies there. Maybe you do something in development.rb that has side effects for the subprocess?

I pretty much always want to force my tests to run themselves and their prerequisites in the "test" environment, especially when ENV['RAILS_ENV'] is set to any of the common defaults (to avoid catastrophic accidents), but I also want to be able to run tests on, say, an environment named "v_2_0_maint_test" or something like that by calling rake test:units RAILS_ENV=v_2_0_maint_test on the command line.

So I have a test_tasks.rake file that prepends a prerequisite onto each of the test tasks that I'm interested in. Since this prerequisite is prepended, any other prerequisites (e.g. db:test:prepare, db:fixtures:load) run in the same environment. This claims the virtue of affecting only the tests you want to affect, and their prerequisites.

namespace :test do |n|  [ n[:units], n[:functionals], n[:integration] ].each do |t|    t.prerequisites.unshift(:set_test_env_dammit)  end  task :set_test_env_dammit do |t|    if [ nil, "", "development", "staging", "production" ].index ENV['RAILS_ENV']      RAILS_ENV = "test"    end  endend

At the top of the test_helper.rb file I have the code

ENV["RAILS_ENV"] = "test"

If you do not have that line then the system problem would run in the default environment (i.e. development).