Issue 30238. Fix for subscribing for a notifications with already cached analysis result.

pkg/analyzer/test/src/dart/analysis/driver_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 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 544 matching lines @@
 
   test_cachedPriorityResults() async {
     var a = _p('/test/bin/a.dart');
     provider.newFile(a, 'var a = 1;');
 
     driver.priorityFiles = [a];
 
     AnalysisResult result1 = await driver.getResult(a);
     expect(driver.test.priorityResults, containsPair(a, result1));
 
-    AnalysisResult result2 = await driver.getResult(a);
-    expect(result2, same(result1));
+    await scheduler.waitForIdle();
+    allResults.clear();
+
+    // Get the (cached) result, not reported to the stream.
+    {
+      AnalysisResult result2 = await driver.getResult(a);
+      expect(result2, same(result1));
+      expect(allResults, isEmpty);
+    }
+
+    // Get the (cached) result, reported to the stream.
+    {
+      AnalysisResult result2 =
+          await driver.getResult(a, sendCachedToStream: true);
+      expect(result2, same(result1));
+
+      expect(allResults, hasLength(1));
+      expect(allResults.single, same(result1));
+    }
   }
 
   test_cachedPriorityResults_flush_onAnyFileChange() async {
     var a = _p('/test/bin/a.dart');
     var b = _p('/test/bin/b.dart');
     provider.newFile(a, 'var a = 1;');
     provider.newFile(a, 'var b = 2;');
 
     driver.priorityFiles = [a];
 
@@ skipping 2148 matching lines @@
     var path = _p('/test.dart');
     expect(() {
       driver.removeFile(path);
     }, throwsStateError);
   }
 
   String _p(String path) => provider.convertPath(path);
 }
 
 class _SourceMock extends TypedMock implements Source {}