Switch directory ownership to git ls-files

lib/code_ownership.rb

@@ -85,14 +85,17 @@ def self.remove_file_annotation!(filename)
       autocorrect: T::Boolean,
       stage_changes: T::Boolean,
       files: T.nilable(T::Array[String]),
+      use_git_ls_files: T::Boolean,
     ).void
   end
   def validate!(
     autocorrect: true,
     stage_changes: true,
-    files: nil
+    files: nil,
+    use_git_ls_files: false
   )
     Private.load_configuration!
+    configuration.use_git_ls_files = use_git_ls_files
 
     tracked_file_subset = if files
       files.select{|f| Private.file_tracked?(f)}

lib/code_ownership/cli.rb

@@ -48,6 +48,11 @@ def self.validate!(argv)
           options[:skip_stage] = true
         end
 
+        opts.on('--use-git-ls-files',
+                'Use git ls-files for findinging .codeowner files instead of globs. Will be faster if in a git context.') do
+          options[:use_git_ls_files] = true
+        end
+
         opts.on('--help', 'Shows this prompt') do
           puts opts
           exit
@@ -67,7 +72,8 @@ def self.validate!(argv)
       CodeOwnership.validate!(
         files: files,
         autocorrect: !options[:skip_autocorrect],
-        stage_changes: !options[:skip_stage]
+        stage_changes: !options[:skip_stage],
+        use_git_ls_files: !!options[:use_git_ls_files]
       )
     end
 

lib/code_ownership/configuration.rb

@@ -12,6 +12,7 @@ class Configuration < T::Struct
     const :skip_codeowners_validation, T::Boolean
     const :raw_hash, T::Hash[T.untyped, T.untyped]
     const :require_github_teams, T::Boolean
+    prop :use_git_ls_files, T::Boolean
 
     sig { returns(Configuration) }
     def self.fetch
@@ -29,7 +30,8 @@ def self.fetch
         js_package_paths: js_package_paths(config_hash),
         skip_codeowners_validation: config_hash.fetch('skip_codeowners_validation', false),
         raw_hash: config_hash,
-        require_github_teams: config_hash.fetch('require_github_teams', false)
+        require_github_teams: config_hash.fetch('require_github_teams', false),
+        use_git_ls_files: config_hash.fetch('use_git_ls_files', false)
       )
     end
 

lib/code_ownership/private/ownership_mappers/directory_ownership.rb

@@ -37,16 +37,22 @@ def update_cache(cache, files)
         # subset of files, but rather we want code ownership for all files.
         #
         sig do
-          override.params(files: T::Array[String]).
-            returns(T::Hash[String, ::CodeTeams::Team])
+          override.params(_files: T::Array[String])
+                  .returns(T::Hash[String, ::CodeTeams::Team])
         end
-        def globs_to_owner(files)
-          # The T.unsafe is because the upstream RBI is wrong for Pathname.glob
-          T
-            .unsafe(Pathname)
-            .glob(File.join('**/', CODEOWNERS_DIRECTORY_FILE_NAME))
-            .map(&:cleanpath)
-            .each_with_object({}) do |pathname, res|
+        def globs_to_owner(_files)
+          file_list =
+            if CodeOwnership.configuration.use_git_ls_files
+              `git ls-files **/#{CODEOWNERS_DIRECTORY_FILE_NAME}`
+                .each_line
+                .map { Pathname.new(_1.strip).cleanpath }
+            else
+              T
+                .unsafe(Pathname)
+                .glob(File.join('**/', CODEOWNERS_DIRECTORY_FILE_NAME))
+                .map(&:cleanpath)
+            end
+          file_list.each_with_object({}) do |pathname, res|
             owner = owner_for_codeowners_file(pathname)
             res[pathname.dirname.cleanpath.join('**/**').to_s] = owner
           end

spec/lib/code_ownership_spec.rb

@@ -23,6 +23,23 @@
           expect { CodeOwnership.validate!(files: ['app/services/test/some_unowned_file.rb']) }.to_not raise_error
           expect { CodeOwnership.validate!(files: ['app/services/[test]/some_unowned_file.rb']) }.to_not raise_error
         end
+
+        context 'when the the configuration for use_git_ls_files is enabled' do
+          before do
+            allow(CodeOwnership.configuration).to receive(:use_git_ls_files) { true }
+            allow_any_instance_of(Object).to receive(:`) do
+              Pathname
+                .glob(File.join('**/', '.codeowner'))
+                .map(&:to_s)
+                .join("\n")
+            end
+          end
+
+          it 'has no validation errors' do
+            expect { CodeOwnership.validate!(files: ['app/services/test/some_unowned_file.rb']) }.to_not raise_error
+            expect { CodeOwnership.validate!(files: ['app/services/[test]/some_unowned_file.rb']) }.to_not raise_error
+          end
+        end
       end
 
       context 'file ownership with [] characters' do