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

pkg/analyzer/test/src/dart/analysis/driver_test.dart

Index: pkg/analyzer/test/src/dart/analysis/driver_test.dart
diff --git a/pkg/analyzer/test/src/dart/analysis/driver_test.dart b/pkg/analyzer/test/src/dart/analysis/driver_test.dart
index cf941a4fbce43bdb788f72332b227dcea3acbd86..c3e6cde79e5e5c0b2aea693d223fb7cf73da37f4 100644
--- a/pkg/analyzer/test/src/dart/analysis/driver_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/driver_test.dart
@@ -562,8 +562,25 @@ part 'part.dart';
     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 {