Interesting interaction with dotenv-rails

[maxjacobson]

Hello again!

We've recently adopted parallel_tests and we've just hit an interesting interaction between this library and dotenv-rails which I'd like to share.

I made an example repo which demonstrates the behavior: https://github.com/maxjacobson/parallel_tests_example_repo

I'll summarize here:

1. I have a gem which is only loaded in the development environment
2. I have an environment variable in .env.development which is only set in the development environment
3. I have a Rails initializer which references that development-only gem only when that environment variable is set
4. When I run bin/rails parallel:create, the command fails because the subprocesses are in a strange state: the Rails environment is test (so the gem is not available), but the environment variables from .env.development are loaded (and so we try to reference it anyway)

I think this behavior basically makes sense, given that the subprocess inherits the parent's environment. I can avoid this issue in a few different ways, such as

1. make that gem available in the test environment too
2. always export RAILS_ENV=test before running bin/rails parallel:create
3. change the conditional to check something like if defined?(JWT) instead of if ENV["ENABLE_COOL_FEATURE"] == "true"

It would have been cool if this had "just worked" though. I'm not sure how to ensure that though... I figured I'd file the issue to share and see if you have any thoughts or guidance.

Thank you!

[grosser]

parallel tasks don't for the loading of the rails env and then shell out to RAILS_ENV=test right ?

Option A:
RAILS_ENV=test before running bin/rails parallel:create
and maybe adding a

Rake::Task["parallel:create"].prerequisites << "parallel_test_needs_test" if ENV["RAILS_ENV"] != "test"
task :parallel_test_needs_test do
  abort "Run this with RAILS_ENV=test"
end

Option B: make rake without 'environment' not load the .env.development file ... but that might break a bunch of other stuff

Option C: force override the env with the .env.test content by using Dotenv.parse(".env.test", overwrite: true)