A FileManager implementation to keep each index file in a separate file system file.

pkg/analysis_server/test/index/store/test_all.dart

Index: pkg/analysis_server/test/index/store/test_all.dart
diff --git a/pkg/analysis_server/test/index/store/test_all.dart b/pkg/analysis_server/test/index/store/test_all.dart
index 6386c226dbcaade0424d185968f36aefc81e4a13..4e67d6b9142618e5ab2e977ffd0b49e2eb3a9a5a 100644
--- a/pkg/analysis_server/test/index/store/test_all.dart
+++ b/pkg/analysis_server/test/index/store/test_all.dart
@@ -8,6 +8,7 @@ import 'package:unittest/unittest.dart';
 
 import 'codec_test.dart' as codec_test;
 import 'collection_test.dart' as collection_test;
+import 'separate_file_manager_test.dart' as separate_file_manager_test;
 import 'split_store_test.dart' as split_store_test;
 
 
@@ -19,6 +20,7 @@ main() {
   group('store', () {
     codec_test.main();
     collection_test.main();
+    separate_file_manager_test.main();
     split_store_test.main();
   });
 }