Merge pull request #16147 from MikeMcQuaid/setup-ruby

cmd/setup-ruby.sh: add new command.

Library/Homebrew/cmd/setup-ruby.sh

@@ -0,0 +1,31 @@
+#:  * `setup-ruby`
+#:
+#:  Installs and configures Homebrew's Ruby.
+#:
+
+# HOMEBREW_LIBRARY is from the user environment.
+# HOMEBREW_RUBY_PATH is set by utils/ruby.sh
+# RUBY_DISABLE_OPTIONS is set by brew.sh
+# HOMEBREW_BREW_FILE is set by extend/ENV/super.rb
+# shellcheck disable=SC2154
+homebrew-setup-ruby() {
+  source "${HOMEBREW_LIBRARY}/Homebrew/utils/ruby.sh"
+  setup-ruby-path
+
+  if [[ -z "${HOMEBREW_DEVELOPER}" && -z "${HOMEBREW_RUBY3}" ]]
+  then
+    return
+  fi
+
+  GEM_VERSION="$("${HOMEBREW_RUBY_PATH}" "${HOMEBREW_RUBY_DISABLE_OPTIONS}" -rrbconfig -e 'puts RbConfig::CONFIG["ruby_version"]')"
+  GEM_HOME="${HOMEBREW_LIBRARY}/Homebrew/vendor/bundle/ruby/${GEM_VERSION}"
+  BUNDLE_GEMFILE="${HOMEBREW_LIBRARY}/Homebrew/Gemfile"
+
+  export GEM_HOME
+  export BUNDLE_GEMFILE
+
+  if ! bundle check &>/dev/null
+  then
+    "${HOMEBREW_BREW_FILE}" install-bundler-gems
+  fi
+}