Rails 5.1.1、ruby 2.4.1、webpacker 2.0，通过rake test:system.
如果有办法查看更多调试日志，例如哪个文件加载哪些模块等，这将很有帮助。
请注意，只有在没有缓存时才会发生，测试应该是。如果有缓存，webpacker 根本不运行，这是正常的。
/usr/local/lib/ruby/gems/2.4.0/gems/webpacker-2.0/lib/tasks/installers.rake:1: warning: already initialized constant INSTALLERS
/usr/local/lib/ruby/gems/2.4.0/gems/webpacker-2.0/lib/tasks/installers.rake:1: warning: previous definition of INSTALLERS was here
/usr/local/lib/ruby/gems/2.4.0/gems/webpacker-2.0/lib/tasks/webpacker/install.rake:1: warning: already initialized constant WEBPACKER_APP_TEMPLATE_PATH
/usr/local/lib/ruby/gems/2.4.0/gems/webpacker-2.0/lib/tasks/webpacker/install.rake:1: warning: previous definition of WEBPACKER_APP_TEMPLATE_PATH was here
Webpacker is installed � �
Using ..../config/webpacker.yml file for setting up webpack paths
Webpacker is installed � �
Using ..../config/webpacker.yml file for setting up webpack paths
[Webpacker] Compiling assets �
[Webpacker] Compiling assets �