add config to webpacker

config/routes.rb

@@ -7,7 +7,7 @@ Sidekiq::Web.set :session_secret, Rails.application.secrets[:secret_key_base]
 
 Rails.application.routes.draw do
   root 'home#index'
-  resources :user_groups
+
   mount LetterOpenerWeb::Engine, at: 'letter_opener' if Rails.env.development?
 
   health_check_routes

config/webpacker.yml

@@ -17,13 +17,12 @@ default: &default
   cache_manifest: false
 
   # Extract and emit a css file
-  extract_css: false
+  extract_css: true
 
   static_assets_extensions:
     - .jpg
     - .jpeg
     - .png
-    - .gif
     - .tiff
     - .ico
     - .svg
@@ -50,10 +49,8 @@ default: &default
 
 development:
   <<: *default
-  compile: true
 
-  # Verifies that correct packages and versions are installed by inspecting package.json, yarn.lock, and node_modules
-  check_yarn_integrity: true
+  compile: true
 
   # Reference: https://webpack.js.org/configuration/dev-server/
   dev_server:
@@ -74,10 +71,12 @@ development:
     watch_options:
       ignored: '**/node_modules/**'
 
-
 test:
   <<: *default
-  compile: true
+
+  # CircleCI precompiles packs prior to running the tests.
+  # Also avoids race conditions in parallel_tests.
+  compile: false
 
   # Compile test packs to a separate directory
   public_output_path: packs-test
@@ -88,8 +87,5 @@ production:
   # Production depends on precompilation of packs prior to booting for performance.
   compile: false
 
-  # Extract and emit a css file
-  extract_css: true
-
   # Cache manifest.json for performance
   cache_manifest: true