Fix projects in a subdir of HOME erroneously load ~/.rubocop.yml

It is common for projects to be in a subdirectory of $HOME, causing
a problem in the ConfigLoader where add_excludes_from_files searches
for the highest file matching .rubocop.yml and finds ~/.rubocop.yml.

This violates the documentation stating that ~/.rubocop.yml will not be
loaded when a project specific file is found first.

Adds tests for config loading behavior and extends behavior for finding
ancestor configs to make it possible to grab the highest config before
the home dir.

changelog/fix_specifically_exclude_rubocop_yml_from.md

@@ -0,0 +1 @@
+* [#12147](https://github.com/rubocop/rubocop/pull/12147): Specifically exclude ~/.rubocop.yml when loading parent excludes when project is a subdir of HOME. ([@martinemde][])

lib/rubocop/config_finder.rb

@@ -21,6 +21,17 @@ def find_config_path(target_dir)
           DEFAULT_FILE
       end
 
+      def find_project_dotfile(target_dir)
+        if project_root
+          find_last_file_upwards(DOTFILE, target_dir, project_root)
+        else
+          files = files_upwards(DOTFILE, target_dir, Dir.home).to_a
+          # skip configs found in the user's home directory
+          files.pop if files.last && File.dirname(files.last) == Dir.home
+          files.last
+        end
+      end
+
       # Returns the path RuboCop inferred as the root of the project. No file
       # searches will go past this directory.
       def project_root
@@ -37,10 +48,6 @@ def find_project_root
         File.dirname(gems_file)
       end
 
-      def find_project_dotfile(target_dir)
-        find_file_upwards(DOTFILE, target_dir, project_root)
-      end
-
       def find_user_dotfile
         return unless ENV.key?('HOME')
 

lib/rubocop/config_loader.rb

@@ -136,7 +136,7 @@ def possible_new_cops?(config)
       end
 
       def add_excludes_from_files(config, config_file)
-        exclusion_file = find_last_file_upwards(DOTFILE, config_file, ConfigFinder.project_root)
+        exclusion_file = ConfigFinder.find_project_dotfile(config_file)
 
         return unless exclusion_file
         return if PathUtil.relative_path(exclusion_file) == PathUtil.relative_path(config_file)

lib/rubocop/file_finder.rb

@@ -6,35 +6,35 @@ module RuboCop
   # Common methods for finding files.
   # @api private
   module FileFinder
-    def self.root_level=(level)
-      @root_level = level
-    end
-
-    def self.root_level?(path, stop_dir)
-      (@root_level || stop_dir) == path.to_s
+    class << self
+      # Root level defines the absolute path of the top level directory
+      # that can be searched for files.
+      #
+      # If the start_dir is not a subdirectory of root_level, root_level is ignored.
+      #
+      # root_level is only used in tests to avoid finding files in directories
+      # outside of the isolated test directory, especially on Windows where
+      # the temporary directory is under the user's home directory.
+      attr_accessor :root_level
     end
 
     def find_file_upwards(filename, start_dir, stop_dir = nil)
-      traverse_files_upwards(filename, start_dir, stop_dir) do |file|
-        # minimize iteration for performance
-        return file if file
-      end
+      files_upwards(filename, start_dir, stop_dir).first
     end
 
     def find_last_file_upwards(filename, start_dir, stop_dir = nil)
-      last_file = nil
-      traverse_files_upwards(filename, start_dir, stop_dir) { |file| last_file = file }
-      last_file
+      files_upwards(filename, start_dir, stop_dir).to_a.last
     end
 
-    private
+    def files_upwards(filename, start_dir, stop_dir = nil)
+      return enum_for(:files_upwards, filename, start_dir, stop_dir) unless block_given?
 
-    def traverse_files_upwards(filename, start_dir, stop_dir)
+      stop_dirs = [stop_dir, FileFinder.root_level].compact.map { |dir| File.expand_path(dir) }
       Pathname.new(start_dir).expand_path.ascend do |dir|
         file = dir + filename
         yield(file.to_s) if file.exist?
 
-        break if FileFinder.root_level?(dir, stop_dir)
+        break if stop_dirs.include?(dir.to_s)
       end
     end
   end

lib/rubocop/rspec/shared_contexts.rb

@@ -11,18 +11,18 @@
       # Make sure to expand all symlinks in the path first. Otherwise we may
       # get mismatched pathnames when loading config files later on.
       tmpdir = File.realpath(tmpdir)
+      root = File.join(tmpdir, 'root')
+      Dir.mkdir(root)
+      RuboCop::FileFinder.root_level = root
 
-      virtual_home = File.expand_path(File.join(tmpdir, 'home'))
+      virtual_home = File.expand_path('home', root)
       Dir.mkdir(virtual_home)
       ENV['HOME'] = virtual_home
       ENV.delete('XDG_CONFIG_HOME')
 
-      base_dir = example.metadata[:project_inside_home] ? virtual_home : tmpdir
-      root = example.metadata[:root]
-      working_dir = root ? File.join(base_dir, 'work', root) : File.join(base_dir, 'work')
 
-      # Make upwards search for .rubocop.yml files stop at this directory.
-      RuboCop::FileFinder.root_level = working_dir
+      base_dir = example.metadata[:project_inside_home] ? virtual_home : root
+      working_dir = File.join(base_dir, 'work')
 
       begin
         FileUtils.mkdir_p(working_dir)

spec/isolated_environment_spec.rb

@@ -10,8 +10,10 @@
   # directory is under the user's home directory. On any platform we don't want
   # a .rubocop.yml file in the temporary directory to affect the outcome of
   # rspec.
+  # This is the only test that should place a file above the working directory.
   it 'is not affected by a config file above the work directory' do
-    create_file('../.rubocop.yml', ['inherit_from: missing_file.yml'])
+    erroneous_file = File.expand_path('../.rubocop.yml', RuboCop::FileFinder.root_level)
+    File.write(erroneous_file, 'inherit_from: missing_file.yml')
     create_file('ex.rb', ['# frozen_string_literal: true'])
     # A return value of 0 means that the erroneous config file was not read.
     expect(cli.run([])).to eq(0)

spec/rubocop/config_loader_spec.rb

@@ -9,12 +9,14 @@
     described_class.debug = true
     # Force reload of default configuration
     described_class.default_configuration = nil
+    RuboCop::ConfigFinder.project_root = nil
   end
 
   after do
     described_class.debug = false
     # Remove custom configuration
     described_class.default_configuration = nil
+    RuboCop::ConfigFinder.project_root = nil
   end
 
   let(:default_config) { described_class.default_configuration }
@@ -80,14 +82,14 @@
       end
     end
 
-    context 'when there is a spurious rubocop config outside of the project', root: 'dir' do
+    context 'when there is a spurious rubocop config outside of the project' do
       let(:dir_path) { 'dir' }
 
       before do
         # Force reload of project root
         RuboCop::ConfigFinder.project_root = nil
-        create_empty_file('Gemfile')
-        create_empty_file('../.rubocop.yml')
+        create_empty_file('dir/Gemfile')
+        create_empty_file('.rubocop.yml')
       end
 
       after do
@@ -96,7 +98,9 @@
       end
 
       it 'ignores the spurious config and falls back to the provided default file if run from the project' do
-        expect(configuration_file_for).to end_with('config/default.yml')
+        Dir.chdir('dir') do
+          expect(configuration_file_for).to end_with('config/default.yml')
+        end
       end
     end
 
@@ -149,6 +153,55 @@
       end
     end
 
+    context 'when the project is in a subdirectory of $HOME', :project_inside_home do
+      let(:file_path) { File.expand_path('~/work/vendor/.rubocop.yml') }
+
+      before do
+        create_file(file_path, <<~YAML)
+          AllCops:
+            Exclude:
+              - ./**
+        YAML
+      end
+
+      it 'gets AllCops/Exclude from the highest directory level' do
+        excludes = configuration_from_file['AllCops']['Exclude']
+        expect(excludes).to eq([File.expand_path('~/work/vendor/**')])
+      end
+
+      context 'and there is a personal config file in the home folder' do
+        before do
+          create_file('~/.rubocop.yml', <<~YAML)
+            AllCops:
+              Exclude:
+                - tmp/**
+          YAML
+        end
+
+        it 'ignores personal AllCops/Exclude' do
+          excludes = configuration_from_file['AllCops']['Exclude']
+          expect(excludes).to eq([File.expand_path('~/work/vendor/**')])
+        end
+
+        context 'and there is a project config higher up but before the home dir' do
+          before do
+            create_file(File.expand_path('~/work/.rubocop.yml'), <<~YAML)
+              AllCops:
+                Exclude:
+                  - docs/**
+            YAML
+          end
+
+          it 'gets AllCops/Exclude from the highest directory level before $HOME' do
+            excludes = configuration_from_file['AllCops']['Exclude']
+            expect(excludes).to eq(
+              [File.expand_path('~/work/vendor/**'), File.expand_path('~/work/docs/**')]
+            )
+          end
+        end
+      end
+    end
+
     context 'when multiple config files exist in ancestor directories' do
       let(:file_path) { 'dir/.rubocop.yml' }
 

spec/rubocop/cop/team_spec.rb

@@ -88,7 +88,7 @@ def a
   describe '#inspect_file', :isolated_environment do
     include FileHelper
 
-    let(:file_path) { '/tmp/example.rb' }
+    let(:file_path) { 'example.rb' }
     let(:source) do
       source = RuboCop::ProcessedSource.from_file(file_path, ruby_version)
       source.config = config
@@ -175,7 +175,7 @@ def a
 
       let(:error_message) do
         'An error occurred while Style/NumericLiterals cop was inspecting ' \
-          '/tmp/example.rb:1:0.'
+          'example.rb:1:0.'
       end
 
       it 'records Team#errors' do
@@ -198,7 +198,7 @@ def a
         RUBY
       end
 
-      let(:file_path) { '/tmp/Gemfile' }
+      let(:file_path) { 'Gemfile' }
 
       let(:buggy_correction) { ->(_corrector) do raise cause end }
       let(:options) { { autocorrect: true } }
@@ -207,7 +207,7 @@ def a
 
       let(:error_message) do
         'An error occurred while Bundler/OrderedGems cop was inspecting ' \
-          '/tmp/Gemfile.'
+          'Gemfile.'
       end
 
       it 'records Team#errors' do