Clarify Rails test use of config environments

fixes rails#2654
asavageiv · Sep 2, 2020 · da4f4b6 · da4f4b6
1 parent 5780a0a
commit da4f4b6
Showing 1 changed file with 13 additions and 0 deletions.
diff --git a/docs/testing.md b/docs/testing.md
@@ -134,3 +134,16 @@ Make sure you configure Rails to serve static files from the public directory in
 # Configure public file server for tests with Cache-Control for performance.
 config.public_file_server.enabled = true
 ```
+
+## Webpacker Configuration Environments and Rails Tests
+
+Webpacker ships with three configuration files in `config/webpack`:
+`test.js`, `development.js`, and `production.js`. `NODE_ENV` determines which
+webpack config it will use, i.e., config/webpack/{development,test,production}.js
+and will impact behavior in your Babel config, i.e., `babel.config.js`.
+`NODE_ENV` is independent of `RAILS_ENV` in Rails.
+
+This means that by default `rails test` or `rspec` will use `development.js`
+_not_ `test.js`, because `NODE_ENV` is `development` by [default](https://github.com/rails/webpacker/blob/bf278f9787704ed0f78038ad7d36c008abc2edfd/lib/install/bin/webpack#L4).
+
+For more information see [Why doesn't Webpacker use my test config when I run Rails tests?](https://rossta.net/blog/why-doesnt-webpacker-use-my-test-config-when-i-run-rails-tests.html)