Watch analysis roots separately.

pkg/analysis_server/test/single_context_manager_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.analysis_server.src.single_context_manager;
 
 import 'dart:core' hide Resource;
 
 import 'package:analysis_server/src/single_context_manager.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
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     // empty folder initially
     callbacks.assertContextFiles(project, []);
     // add file
     String file = '$project/foo.dart';
     resourceProvider.newFile(file, 'contents');
     // the file was added
     await pumpEventQueue();
     callbacks.assertContextFiles(project, [file]);
   }
 
+  test_watch_addFile_afterChangingRoots() async {
+    String contextPath = '/context';
+    String root1 = '$contextPath/root1';
+    String root2 = '$contextPath/root2';
+    String file1 = '$root1/file1.dart';
+    String file2 = '$root2/file2.dart';
+    manager.setRoots(<String>[root1], <String>[], <String, String>{});
+    manager.setRoots(<String>[root2], <String>[], <String, String>{});
+    manager.setRoots(<String>[root1, root2], <String>[], <String, String>{});
+    manager.setRoots(<String>[root2], <String>[], <String, String>{});
+    // empty folder initially
+    callbacks.assertContextFiles(root2, []);
+    // add files
+    resourceProvider.newFile(file1, '');
+    resourceProvider.newFile(file2, '');
+    // the file was added
+    await pumpEventQueue();
+    callbacks.assertContextFiles(root2, [file2]);
+  }
+
   test_watch_addFile_excluded() async {
     String project = '/project';
     String folderA = '$project/aaa';
     String folderB = '$project/bbb';
     String fileA = '$folderA/a.dart';
     String fileB = '$folderB/b.dart';
     // create files
     resourceProvider.newFile(fileA, 'library a;');
     // set roots
     manager.setRoots(<String>[project], <String>[folderB], <String, String>{});
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     manager.processPlugins(plugins);
   }
 }
 
 class TestUriResolver extends UriResolver {
   @override
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     return null;
   }
 }