Fixing a bug in DiagnosticEvent that results into empty events (#9688)

Author: soninaren

src/WebJobs.Script.WebHost/Diagnostics/DiagnosticEventTableStorageRepository.cs

@@ -144,12 +144,9 @@ internal virtual async Task FlushLogs(CloudTable table = null)
             catch (Exception ex)
             {
                 _logger.LogError(ex, $"Unable to get table reference or create table. Aborting write operation.");
-                return;
-            }
-            finally
-            {
                 // Clearing the memory cache to avoid memory build up.
                 _events.Clear();
+                return;
             }
 
             // Assigning a new empty directory to reset the event count in the new duration window.

test/WebJobs.Script.Tests.Integration/Diagnostics/DiagnosticEventTableStorageRepositoryTests.cs

@@ -249,6 +249,28 @@ public async Task ExecuteBatchAsync_WritesToTableStorage()
             Assert.Equal(results.Count(), 1);
         }
 
+        [Fact]
+        public async Task FlushLogs_WritesToTableStorage()
+        {
+            IEnvironment testEnvironment = new TestEnvironment();
+            testEnvironment.SetEnvironmentVariable(EnvironmentSettingNames.AzureWebsitePlaceholderMode, "0");
+
+            DiagnosticEventTableStorageRepository repository =
+                new DiagnosticEventTableStorageRepository(_configuration, _hostIdProvider, testEnvironment, _logger);
+
+            var table = repository.GetDiagnosticEventsTable();
+            await TableStorageHelpers.CreateIfNotExistsAsync(table, 2);
+            await EmptyTableAsync(table);
+
+            var dateTime = DateTime.UtcNow;
+            var diagnosticEvent = new DiagnosticEvent("hostId", dateTime);
+            repository.Events.TryAdd("EC123", diagnosticEvent);
+            await repository.FlushLogs(table);
+
+            var results = ExecuteQuery(table, new TableQuery());
+            Assert.Equal(results.Count(), 1);
+        }
+
         [Fact]
         public async Task ExecuteBatchAsync_LogsError()
         {