[rubygems/rubygems] Avoid concurrent builds of Bundler when running specs

Instead, build it during setup when in CI.

This should avoid some Windows specific test failures when Bundler
copies the same files from multiple processes and runs into EACESS
errors.

https://github.com/rubygems/rubygems/commit/c194a1d753

spec/bundler/spec_helper.rb

@@ -87,11 +87,10 @@ RSpec.configure do |config|
     # Don't wrap output in tests
     ENV["THOR_COLUMNS"] = "10000"
 
-    extend(Spec::Helpers)
-    system_gems :bundler, path: pristine_system_gem_path
-  end
+    Spec::Helpers.install_dev_bundler unless ENV["CI"]
+
+    extend(Spec::Builders)
 
-  config.before :all do
     check_test_gems!
 
     build_repo1

spec/bundler/support/builders.rb

@@ -5,6 +5,11 @@ require "shellwords"
 
 module Spec
   module Builders
+    def self.extended(mod)
+      mod.extend Path
+      mod.extend Helpers
+    end
+
     def self.constantize(name)
       name.delete("-").upcase
     end
@@ -22,7 +27,7 @@ module Spec
     end
 
     def build_repo1
-      rake_path = Dir["#{Path.base_system_gems}/**/rake*.gem"].first
+      rake_path = Dir["#{base_system_gems}/**/rake*.gem"].first
 
       build_repo gem_repo1 do
         FileUtils.cp rake_path, "#{gem_repo1}/gems/"
@@ -240,12 +245,12 @@ module Spec
     end
 
     def check_test_gems!
-      rake_path = Dir["#{Path.base_system_gems}/**/rake*.gem"].first
+      rake_path = Dir["#{base_system_gems}/**/rake*.gem"].first
 
       if rake_path.nil?
-        FileUtils.rm_rf(Path.base_system_gems)
+        FileUtils.rm_rf(base_system_gems)
         Spec::Rubygems.install_test_deps
-        rake_path = Dir["#{Path.base_system_gems}/**/rake*.gem"].first
+        rake_path = Dir["#{base_system_gems}/**/rake*.gem"].first
       end
 
       if rake_path.nil?
@@ -261,9 +266,9 @@ module Spec
       @_build_path = "#{path}/gems"
       @_build_repo = File.basename(path)
       yield
-      with_gem_path_as Path.base_system_gem_path do
-        Dir[Spec::Path.base_system_gem_path.join("gems/rubygems-generate_index*/lib")].first ||
-          raise("Could not find rubygems-generate_index lib directory in #{Spec::Path.base_system_gem_path}")
+      with_gem_path_as base_system_gem_path do
+        Dir[base_system_gem_path.join("gems/rubygems-generate_index*/lib")].first ||
+          raise("Could not find rubygems-generate_index lib directory in #{base_system_gem_path}")
 
         command = "generate_index"
         command += " --no-compact" if !build_compact_index && gem_command(command + " --help").include?("--[no-]compact")

spec/bundler/support/helpers.rb

@@ -11,6 +11,12 @@ module Spec
     include Spec::Options
     include Spec::Subprocess
 
+    def self.extended(mod)
+      mod.extend Spec::Path
+      mod.extend Spec::Options
+      mod.extend Spec::Subprocess
+    end
+
     def reset!
       Dir.glob("#{tmp}/{gems/*,*}", File::FNM_DOTMATCH).each do |dir|
         next if %w[base base_system remote1 rubocop standard gems rubygems . ..].include?(File.basename(dir))
@@ -267,6 +273,12 @@ module Spec
       end
     end
 
+    def self.install_dev_bundler
+      extend self
+
+      system_gems :bundler, path: pristine_system_gem_path
+    end
+
     def install_gem(path, install_dir, default = false)
       raise "OMG `#{path}` does not exist!" unless File.exist?(path)
 
@@ -277,6 +289,8 @@ module Spec
     end
 
     def with_built_bundler(version = nil, &block)
+      require_relative "builders"
+
       Builders::BundlerBuilder.new(self, "bundler", version)._build(&block)
     end
 

spec/bundler/support/rubygems_ext.rb

@@ -75,9 +75,15 @@ module Spec
     end
 
     def install_test_deps
+      Gem.clear_paths
+
       install_gems(test_gemfile, Path.base_system_gems.to_s)
       install_gems(rubocop_gemfile, Path.rubocop_gems.to_s)
       install_gems(standard_gemfile, Path.standard_gems.to_s)
+
+      # For some reason, doing this here crashes on JRuby + Windows. So defer to
+      # when the test suite is running in that case.
+      Helpers.install_dev_bundler unless Gem.win_platform? && RUBY_ENGINE == "jruby"
     end
 
     def check_source_control_changes(success_message:, error_message:)