Allow declaration of project addons

jekyll/add-ons.markdown

@@ -61,6 +61,10 @@ The Ruby LSP discovers add-ons based on the existence of an `addon.rb` file plac
 example, `my_gem/lib/ruby_lsp/my_gem/addon.rb`. This file must declare the add-on class, which can be used to perform any
 necessary activation when the server starts.
 
+{: .note }
+Projects can also define their own private add-ons for functionality that only applies to a particular application. As
+long as a file matching `ruby_lsp/**/addon.rb` exists inside of the workspace (not necessarily at the root), it will be
+loaded by the Ruby LSP.
 
 ```ruby
 # frozen_string_literal: true

lib/ruby_indexer/lib/ruby_indexer/configuration.rb

@@ -235,6 +235,8 @@ def initial_excluded_gems
 
       excluded.uniq!
       excluded.map(&:name)
+    rescue Bundler::GemfileNotFound
+      []
     end
   end
 end

lib/ruby_lsp/addon.rb

@@ -65,6 +65,15 @@ def load_addons(global_state, outgoing_queue)
           e
         end
 
+        project_addons = Dir.glob(File.join(global_state.workspace_path, "**", "ruby_lsp/**/addon.rb"))
+        project_addons.each do |addon_path|
+          next if addon_path == __FILE__
+
+          require File.expand_path(addon_path)
+        rescue => e
+          errors << e
+        end
+
         # Instantiate all discovered addon classes
         self.addons = addon_classes.map(&:new)
         self.file_watcher_addons = addons.select { |addon| addon.respond_to?(:workspace_did_change_watched_files) }

test/addon_test.rb

@@ -131,5 +131,40 @@ def test_addons_receive_settings
     ensure
       T.must(outgoing_queue).close
     end
+
+    def test_project_specific_addons
+      Dir.mktmpdir do |dir|
+        Dir.chdir(dir) do
+          addon_dir = File.join(dir, "lib", "ruby_lsp", "test_addon")
+          FileUtils.mkdir_p(addon_dir)
+          File.write(File.join(addon_dir, "addon.rb"), <<~RUBY)
+            class ProjectAddon < RubyLsp::Addon
+              attr_reader :hello
+
+              def activate(global_state, outgoing_queue)
+                @hello = true
+              end
+
+              def name
+                "Project Addon"
+              end
+            end
+          RUBY
+
+          queue = Thread::Queue.new
+          global_state = GlobalState.new
+          global_state.apply_options({
+            workspaceFolders: [{ uri: URI::Generic.from_path(path: dir).to_s }],
+          })
+          Addon.load_addons(global_state, queue)
+
+          addon = Addon.get("Project Addon")
+          assert_equal("Project Addon", addon.name)
+          assert_predicate(T.unsafe(addon), :hello)
+        ensure
+          T.must(queue).close
+        end
+      end
+    end
   end
 end