Move gem group setting to separate, cacheable file

.gitignore

@@ -26,6 +26,7 @@
 # Ignore Bundler files
 **/.bundle/bin
 **/.bundle/cache
+**/vendor/bundle/ruby/.homebrew_gem_groups
 **/vendor/bundle/ruby/*/bundler.lock
 **/vendor/bundle/ruby/*/bin
 **/vendor/bundle/ruby/*/build_info/

Library/Homebrew/dev-cmd/install-bundler-gems.rb

@@ -13,7 +13,13 @@ module Homebrew
         Install Homebrew's Bundler gems.
       EOS
       comma_array "--groups",
-                  description: "Installs the specified comma-separated list of gem groups (default: last used)."
+                  description: "Installs the specified comma-separated list of gem groups (default: last used). " \
+                               "Replaces any previously installed groups."
+      comma_array "--add-groups",
+                  description: "Installs the specified comma-separated list of gem groups, " \
+                               "in addition to those already installed."
+
+      conflicts "--groups", "--add-groups"
 
       named_args :none
     end
@@ -22,13 +28,13 @@ module Homebrew
   def install_bundler_gems
     args = install_bundler_gems_args.parse
 
-    groups = args.groups
+    groups = args.groups || args.add_groups || []
 
-    # Clear previous settings. We want to fully replace - not append.
-    Homebrew::Settings.delete(:gemgroups) if groups
-
-    groups ||= []
-    groups |= Homebrew.valid_gem_groups if groups.delete("all")
+    if groups.delete("all")
+      groups |= Homebrew.valid_gem_groups
+    elsif args.groups # if we have been asked to replace
+      Homebrew.forget_user_gem_groups!
+    end
 
     Homebrew.install_bundler_gems!(groups: groups)
   end

Library/Homebrew/settings.rb

@@ -31,7 +31,7 @@ module Homebrew
     def self.delete(setting, repo: HOMEBREW_REPOSITORY)
       return unless (repo/".git/config").exist?
 
-      return if read(setting, repo: repo).blank?
+      return if read(setting, repo: repo).nil?
 
       Kernel.system("git", "-C", repo.to_s, "config", "--unset-all", "homebrew.#{setting}", exception: true)
     end

Library/Homebrew/utils/gems.rb

@@ -12,6 +12,9 @@ module Homebrew
   # After updating this, run `brew vendor-gems --update=--bundler`.
   HOMEBREW_BUNDLER_VERSION = "2.4.18"
 
+  GEM_GROUPS_FILE = (HOMEBREW_LIBRARY_PATH/"vendor/bundle/ruby/.homebrew_gem_groups").freeze
+  private_constant :GEM_GROUPS_FILE
+
   module_function
 
   # @api private
@@ -151,6 +154,33 @@ module Homebrew
     ENV["BUNDLER_VERSION"] = old_bundler_version
   end
 
+  def user_gem_groups
+    @user_gem_groups ||= if GEM_GROUPS_FILE.exist?
+      GEM_GROUPS_FILE.readlines(chomp: true)
+    else
+      # Backwards compatibility. This else block can be replaced by `[]` by the end of 2023.
+      require "settings"
+      groups = Homebrew::Settings.read(:gemgroups)&.split(";") || []
+      write_user_gem_groups(groups)
+      Homebrew::Settings.delete(:gemgroups)
+      groups
+    end
+  end
+
+  def write_user_gem_groups(groups)
+    GEM_GROUPS_FILE.write(groups.join("\n"))
+  end
+
+  def forget_user_gem_groups!
+    if GEM_GROUPS_FILE.exist?
+      GEM_GROUPS_FILE.truncate(0)
+    else
+      # Backwards compatibility. This else block can be removed by the end of 2023.
+      require "settings"
+      Homebrew::Settings.delete(:gemgroups)
+    end
+  end
+
   def install_bundler_gems!(only_warn_on_failure: false, setup_path: true, groups: [])
     old_path = ENV.fetch("PATH", nil)
     old_gem_path = ENV.fetch("GEM_PATH", nil)
@@ -174,7 +204,7 @@ module Homebrew
     require "settings"
 
     # Combine the passed groups with the ones stored in settings
-    groups |= (Homebrew::Settings.read(:gemgroups)&.split(";") || [])
+    groups |= (user_gem_groups & valid_gem_groups)
     groups.sort!
 
     ENV["BUNDLE_GEMFILE"] = gemfile
@@ -223,7 +253,7 @@ module Homebrew
       end
 
       if bundle_installed
-        Homebrew::Settings.write(:gemgroups, groups.join(";"))
+        write_user_gem_groups(groups)
         @bundle_installed_groups = groups
       end
     end

completions/bash/brew

@@ -1287,6 +1287,7 @@ _brew_install_bundler_gems() {
   case "${cur}" in
     -*)
       __brewcomp "
+      --add-groups
       --debug
       --groups
       --help

completions/fish/brew.fish

@@ -919,8 +919,9 @@ __fish_brew_complete_arg 'install; and not __fish_seen_argument -l formula -l fo
 
 
 __fish_brew_complete_cmd 'install-bundler-gems' 'Install Homebrew\'s Bundler gems'
+__fish_brew_complete_arg 'install-bundler-gems' -l add-groups -d 'Installs the specified comma-separated list of gem groups, in addition to those already installed'
 __fish_brew_complete_arg 'install-bundler-gems' -l debug -d 'Display any debugging information'
-__fish_brew_complete_arg 'install-bundler-gems' -l groups -d 'Installs the specified comma-separated list of gem groups (default: last used)'
+__fish_brew_complete_arg 'install-bundler-gems' -l groups -d 'Installs the specified comma-separated list of gem groups (default: last used). Replaces any previously installed groups'
 __fish_brew_complete_arg 'install-bundler-gems' -l help -d 'Show this message'
 __fish_brew_complete_arg 'install-bundler-gems' -l quiet -d 'Make some output more quiet'
 __fish_brew_complete_arg 'install-bundler-gems' -l verbose -d 'Make some output more verbose'

completions/zsh/_brew

@@ -1139,8 +1139,9 @@ _brew_install() {
 # brew install-bundler-gems
 _brew_install_bundler_gems() {
   _arguments \
+    '(--groups)--add-groups[Installs the specified comma-separated list of gem groups, in addition to those already installed]' \
     '--debug[Display any debugging information]' \
-    '--groups[Installs the specified comma-separated list of gem groups (default: last used)]' \
+    '(--add-groups)--groups[Installs the specified comma-separated list of gem groups (default: last used). Replaces any previously installed groups]' \
     '--help[Show this message]' \
     '--quiet[Make some output more quiet]' \
     '--verbose[Make some output more verbose]'

docs/Manpage.md

@@ -1300,12 +1300,14 @@ The generated files are written to the current directory.
 
 Generate Homebrew's manpages and shell completions.
 
-### `install-bundler-gems` [`--groups=`]
+### `install-bundler-gems` [`--groups=`] [`--add-groups=`]
 
 Install Homebrew's Bundler gems.
 
 * `--groups`:
-  Installs the specified comma-separated list of gem groups (default: last used).
+  Installs the specified comma-separated list of gem groups (default: last used). Replaces any previously installed groups.
+* `--add-groups`:
+  Installs the specified comma-separated list of gem groups, in addition to those already installed.
 
 ### `irb` [`--examples`] [`--pry`]
 

manpages/brew.1

@@ -1858,12 +1858,16 @@ Generate API data without writing it to files\.
 .SS "\fBgenerate\-man\-completions\fR"
 Generate Homebrew\'s manpages and shell completions\.
 .
-.SS "\fBinstall\-bundler\-gems\fR [\fB\-\-groups=\fR]"
+.SS "\fBinstall\-bundler\-gems\fR [\fB\-\-groups=\fR] [\fB\-\-add\-groups=\fR]"
 Install Homebrew\'s Bundler gems\.
 .
 .TP
 \fB\-\-groups\fR
-Installs the specified comma\-separated list of gem groups (default: last used)\.
+Installs the specified comma\-separated list of gem groups (default: last used)\. Replaces any previously installed groups\.
+.
+.TP
+\fB\-\-add\-groups\fR
+Installs the specified comma\-separated list of gem groups, in addition to those already installed\.
 .
 .SS "\fBirb\fR [\fB\-\-examples\fR] [\fB\-\-pry\fR]"
 Enter the interactive Homebrew Ruby shell\.