Refactor Bundler tests to invoke RubyGems API directly

[colby-swandale]

Some Bundler tests currently spawn a subshell to invoke RubyGems. We're moving away from this pattern to speed up the test suite.

This PR refactors those tests to call the RubyGems API directly instead.

The ultimate prize is replacing the bundler and bundle helpers in the test suite entirely, but this serves as a good stepping stone towards that.

[Copilot]

Pull request overview

This PR refactors Bundler tests to invoke the RubyGems API directly instead of spawning subshells, improving test suite performance. The primary change removes the gem_command helper method and replaces all its usages with direct API calls to RubyGems classes.

• Removes the gem_command helper that spawned subshells for gem operations
• Refactors install_gem to use Gem::Installer.at API directly
• Adds uninstall_gem and installed_gems_list helper methods that call RubyGems APIs

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
bundler/spec/support/helpers.rb	Removes gem_command method; refactors install_gem to use Gem::Installer.at; adds new uninstall_gem and installed_gems_list helper methods for direct API calls
bundler/spec/support/builders.rb	Replaces gem build subshell command with direct Gem::Package.build API call
bundler/spec/install/gems/compact_index_spec.rb	Updates test to use new uninstall_gem helper instead of gem_command
bundler/spec/commands/clean_spec.rb	Updates tests to use new installed_gems_list helper instead of gem_command :list
bundler/spec/commands/check_spec.rb	Updates test to use new uninstall_gem helper instead of gem_command
bundler/spec/bundler/gem_helper_spec.rb	Updates test to use new installed_gems_list helper instead of gem_command :list

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[Copilot]

The installed_gems_list method manually saves and restores ENV["GEM_HOME"], but this codebase has an established pattern for temporary environment variable modifications using the without_env_side_effects helper (see lines 393-415). Using this helper would be more consistent with the codebase's patterns and provide better safety guarantees, as it ensures all ENV changes are properly restored even if an exception occurs during the begin block.

[Copilot]

The uninstall_gem method should temporarily set ENV["GEM_HOME"] to ensure Gem::Uninstaller operates on the correct gem installation directory. Without this, the uninstaller may not properly locate gems in the specified install_dir, especially when it differs from the current ENV["GEM_HOME"]. Consider wrapping the uninstaller logic with temporary ENV["GEM_HOME"] modification and Gem.clear_paths calls, similar to how installed_gems_list handles this.

Suggested change

	uninstaller = Gem::Uninstaller.new(
	name,
	install_dir: gem_home,
	ignore: true,
	executables: true,
	all: true
	)
	uninstaller.uninstall
	old_gem_home = ENV["GEM_HOME"]
	ENV["GEM_HOME"] = gem_home
	Gem.clear_paths
	begin
	uninstaller = Gem::Uninstaller.new(
	name,
	install_dir: gem_home,
	ignore: true,
	executables: true,
	all: true
	)
	uninstaller.uninstall
	ensure
	ENV["GEM_HOME"] = old_gem_home
	Gem.clear_paths
	end