Rails 6.1、Ruby 3.0.0：测试错误，因为它们无法加载 rexml

Question

我已经使用 Ruby 3.0.0 从头开始​​创建了一个新的 Rails 6.1 应用程序。

我已经运行db:create并生成了一个带有一些字符串列的单个模型，后跟rails db:migrate.

我跑了rails test但是得到了这个需要 rexml 错误：

/Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:34:in `require': cannot load such file -- rexml/document (LoadError)
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:332:in `block in require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:299:in `load_dependency'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:332:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/selenium-webdriver-3.142.7/lib/selenium/webdriver/firefox.rb:22:in `<main>'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:332:in `block in require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:299:in `load_dependency'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:332:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/webdrivers-4.4.1/lib/webdrivers/geckodriver.rb:72:in `<main>'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:332:in `block in require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:299:in `load_dependency'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/activesupport-6.1.0/lib/active_support/dependencies.rb:332:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/webdrivers-4.4.1/lib/webdrivers.rb:4:in `<main>'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/runtime.rb:66:in `block (2 levels) in require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/runtime.rb:61:in `each'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/runtime.rb:61:in `block in require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/runtime.rb:50:in `each'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/runtime.rb:50:in `require'
  from /Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler.rb:174:in `require'
  from /Users/froop/Rails/froop_app/config/application.rb:7:in `<top (required)>'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application.rb:92:in `require'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application.rb:92:in `preload'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application.rb:157:in `serve'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application.rb:145:in `block in run'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application.rb:139:in `loop'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application.rb:139:in `run'
  from /Users/froop/.rvm/gems/ruby-3.0.0/gems/spring-2.1.1/lib/spring/application/boot.rb:19:in `<top (required)>'
  from <internal:/Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
  from <internal:/Users/froop/.rvm/rubies/ruby-3.0.0/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
  from -e:1:in `<main>'

我完全不确定是什么原因造成的。Rails 是最新的。任何人都可以指出我正确的方向吗？

Answer 1

rexmlgem 是自 Ruby 3.0.0 以来的捆绑 gem。所以你必须添加rexml到Gemfile.

在 Ruby 2.6 和 2.7 上，rexmlgem 是默认 gem。因此，rexml如果Gemfile不包括，则使用默认值rexml。在这些版本的红宝石，您必须添加rexml到Gemfile只有当你想使用特定rexml版本。

Answer 2

要安装 rexml，只需粘贴：gem 'rexml', '~> 3.2', '>= 3.2.4'在 Gemfile 中。你可以在https://rubygems.org/gems/rexml找到它

Answer 3

为 Kazuhiro 的出色答案添加信息。

Ruby 一直在经历一个Gemifying Ruby的过程——将 Ruby 从一个标准库分解为 Gems。

在 Ruby 2.7 中，rexml gem 是一个“默认 gem”，这意味着它不能被删除并且可能需要它而无需在 Gemfiles 中将它们声明为依赖项。

在 Ruby 3.0 中，rexml gem 是一个“捆绑的 gem”：

捆绑的 gem 是默认 Ruby 安装附带的常规 gem。这些库在 Ruby 核心团队之外维护，必要时可以卸载。与其他 3rd-party gem 一样，您必须将它们包含到 gemspec 或 gemfile 中。

strzibny 的博客文章 - Ruby 中的默认 gem 和捆绑 gem 是什么？

因此，在 Ruby 3.0.0 中更改为捆绑的 gem（从 2.7 中的默认 Gem 开始），因此如果使用它，则必须将其添加到 Gemfile 中。