Provide a way for addon developers to get an addon by name (#2216)

lib/ruby_lsp/addon.rb

@@ -72,6 +72,15 @@ def load_addons(global_state, outgoing_queue)
           addon.add_error(e)
         end
       end
+
+      # Intended for use by tests for addons
+      sig { params(addon_name: String).returns(Addon) }
+      def get(addon_name)
+        addon = addons.find { |addon| addon.name == addon_name }
+        raise "Could not find addon '#{addon_name}'" unless addon
+
+        addon
+      end
     end
 
     sig { void }

test/addon_test.rb

@@ -99,5 +99,16 @@ def workspace_did_change_watched_files(changes); end
         Addon.file_watcher_addons.clear
       end
     end
+
+    def test_get_an_addon_by_name
+      addon = Addon.get("My Addon")
+      assert_equal("My Addon", addon.name)
+    end
+
+    def test_raises_if_an_addon_cannot_be_found
+      assert_raises do
+        Addon.get("Invalid Addon")
+      end
+    end
   end
 end