"webpacker:yarn_install" Task removes dev dependencies

[odlp]

On CircleCI, with a Rails 4.2 app, our RSpec test suite precompiles assets. This triggers a webpacker:yarn_install and webpacker:compile:

webpacker/lib/tasks/webpacker/compile.rake

Lines 11 to 19 in 54c0a64

	def enhance_assets_precompile
	Rake::Task["assets:precompile"].enhance do
	unless Rake::Task.task_defined?("yarn:install")
	# For Rails < 5.1
	Rake::Task["webpacker:yarn_install"].invoke
	end
	Rake::Task["webpacker:compile"].invoke
	end
	end

Unfortunately the webpacker:yarn_install task isn't environment-aware:

webpacker/lib/tasks/webpacker/yarn_install.rake

Line 4 in 54c0a64

system "yarn install --no-progress --production"

The --production flag ends up removing the JS dev dependencies. On CI this means we'd have to re-run yarn install before running JS unit tests or redefine the Rake task.

Rough overview of the steps on CI:

yarn install
ls node_modules | wc -l # 966

bundle exec rspec
ls node_modules | wc -l # 666

yarn test

# yarn run v1.5.1
# $ RAILS_ENV=test node_modules/.bin/karma start --single-run
# sh: node_modules/.bin/karma: No such file or directory

[luccasmaso]

Nice one, spent some hours until discover this )=

[odlp]

As a temporary workaround one can redefine the Rake task:

# lib/tasks/webpacker.rake

# Redefining task so we don't remove the dev dependencies when running on CI
Rake::Task["webpacker:yarn_install"].clear

namespace :webpacker do
  desc "Support for older Rails versions. Install all JavaScript dependencies as specified via Yarn"
  task :yarn_install do
    if ENV["RAILS_ENV"] == "production"
      system "yarn install --no-progress --frozen-lockfile --production"
    else
      system "yarn install --no-progress"
    end
  end
end

[odlp]

Closing - fixed in #1331