Add FileSystemState.knownFilesSetChanges stream.

pkg/analyzer/test/src/dart/analysis/file_state_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.
 
+import 'dart:async';
 import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/dart/analysis/byte_store.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart' show PerformanceLog;
 import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/dart/analysis/top_level_declaration.dart';
@@ skipping 540 matching lines @@
     when(generatedSource.fullName).thenReturn(generatedPath);
     when(generatedSource.uri).thenReturn(uri);
 
     when(generatedUriResolver.resolveAbsolute(uri, uri))
         .thenReturn(generatedSource);
 
     expect(fileSystemState.hasUri(templatePath), isFalse);
     expect(fileSystemState.hasUri(generatedPath), isTrue);
   }
 
+  test_knownFilesSetChanges() async {
+    fileSystemState.test.knownFilesDelay = new Duration(milliseconds: 5);
+
+    String a = _p('/test/lib/a.dart');
+    String b = _p('/test/lib/b.dart');
+    String c = _p('/test/lib/c.dart');
+    provider.newFile(
+        a,
+        r'''
+import 'b.dart';
+''');
+    provider.newFile(b, '');
+    provider.newFile(c, '');
+
+    Stream<KnownFilesSetChange> broadcastEvents =
+        fileSystemState.knownFilesSetChanges.asBroadcastStream();
+
+    FileState file = fileSystemState.getFileForPath(a);
+    {
+      KnownFilesSetChange event = await broadcastEvents.first;
+      expect(event.added, contains(a));
+      expect(event.added, contains(b));
+      expect(event.removed, isEmpty);
+    }
+
+    // Update a.dart to import c.dart and refresh.
+    // So, c.dart should be reported as added in the next change event.
+    provider.newFile(
+        a,
+        r'''
+import 'b.dart';
+import 'c.dart';
+''');
+    file.refresh();
+    {
+      KnownFilesSetChange event = await broadcastEvents.first;
+      expect(event.added, contains(c));
+      expect(event.removed, isEmpty);
+    }
+  }
+
   test_referencedNames() {
     String path = _p('/aaa/lib/a.dart');
     provider.newFile(
         path,
         r'''
 A foo(B p) {
   foo(null);
   C c = new C(p);
   return c;
 }
@@ skipping 256 matching lines @@
   String _p(String path) => provider.convertPath(path);
 
   static String _md5(String content) {
     return hex.encode(md5.convert(UTF8.encode(content)).bytes);
   }
 }
 
 class _GeneratedUriResolverMock extends TypedMock implements UriResolver {}
 
 class _SourceMock extends TypedMock implements Source {}