Fix failing test

Author: andyw8

test/ruby_lsp_rails/indexing_enhancement_test.rb

@@ -7,21 +7,23 @@ module RubyLsp
   module Rails
     class IndexingEnhancementTest < ActiveSupport::TestCase
       class << self
-        # For these tests, it's convenient to have the index fully populated with Rails information, but we don't have
-        # to reindex on every single example or that will be too slow
+        # For these tests, it's convenient to have the index fully populated with Rails information.
         def populated_index
-          @index ||= begin
-            index = RubyIndexer::Index.new
-            index.index_all
-            index
-          end
+          index = RubyIndexer::Index.new
+          index.index_all
+          index
         end
       end
 
       def setup
         @index = self.class.populated_index
       end
 
+      def teardown
+        # Prevent state leaking between tests
+        @index = nil
+      end
+
       test "ClassMethods module inside concerns are automatically extended" do
         @index.index_single(RubyIndexer::IndexablePath.new(nil, "/fake.rb"), <<~RUBY)
           module Verifiable
@@ -69,7 +71,7 @@ class Post
           module Verifiable
             extend ActiveSupport::Concern
 
-            class_methods
+            # class_methods
           end
 
           class Post