[rubygems/rubygems] Support running specs against a tarball

When bundler specs are run from a ruby tarball (ruby-core does this),
there's no git folder, so `git ls-files` fails.

Support this case by making specs rely on the list of files from the
bundler gemspec instead, and invert the spec that makes sure we ship the
right set of files.

As per the other quality specs, skip them in this case.

https://github.com/rubygems/rubygems/commit/b28d5ec931

spec/bundler/quality_spec.rb

@@ -216,7 +216,7 @@ RSpec.describe "The library itself" do
   end
 
   it "ships the correct set of files" do
-    git_list = shipped_files
+    git_list = git_ls_files(ruby_core? ? "lib/bundler lib/bundler.rb man/bundle* man/gemfile* libexec/bundle*" : "lib man exe CHANGELOG.md LICENSE.md README.md bundler.gemspec")
 
     gem_list = loaded_gemspec.files
 

spec/bundler/support/helpers.rb

@@ -331,7 +331,7 @@ module Spec
 
         build_metadata = {
           :built_at => loaded_gemspec.date.utc.strftime("%Y-%m-%d"),
-          :git_commit_sha => sys_exec("git rev-parse --short HEAD", :dir => source_root).strip,
+          :git_commit_sha => git_commit_sha,
         }
 
         replace_build_metadata(build_metadata, dir: build_path) # rubocop:disable Style/HashSyntax

spec/bundler/support/path.rb

@@ -68,7 +68,7 @@ module Spec
     end
 
     def shipped_files
-      @shipped_files ||= git_ls_files(shipped_files_glob)
+      @shipped_files ||= loaded_gemspec.files
     end
 
     def lib_tracked_files
@@ -231,20 +231,22 @@ module Spec
       end
     end
 
+    def git_commit_sha
+      ruby_core_tarball? ? "unknown" : sys_exec("git rev-parse --short HEAD", :dir => source_root).strip
+    end
+
   private
 
     def git_ls_files(glob)
-      sys_exec("git ls-files -z -- #{glob}", :dir => source_root).split("\x0")
+      skip "Not running on a git context, since running tests from a tarball" if ruby_core_tarball?
+
+      sys_exec!("git ls-files -z -- #{glob}", :dir => source_root).split("\x0")
     end
 
     def tracked_files_glob
       ruby_core? ? "lib/bundler lib/bundler.rb spec/bundler man/bundle*" : ""
     end
 
-    def shipped_files_glob
-      ruby_core? ? "lib/bundler lib/bundler.rb man/bundle* man/gemfile* libexec/bundle*" : "lib man exe CHANGELOG.md LICENSE.md README.md bundler.gemspec"
-    end
-
     def lib_tracked_files_glob
       ruby_core? ? "lib/bundler lib/bundler.rb" : "lib"
     end
@@ -253,6 +255,14 @@ module Spec
       ruby_core? ? "man/bundle* man/gemfile*" : "man"
     end
 
+    def git_root
+      ruby_core? ? source_root : source_root.parent
+    end
+
+    def ruby_core_tarball?
+      !git_root.join(".git").directory?
+    end
+
     extend self
   end
 end