Fix #1629 - default event hubs batch size is incorrect

It looks like when the event hubs extension was updated to the new model to parse host.json, the same code in the script layer was not removed, causing this issue. Added tests and also verified manually that this fix works.

Author: paulbatum

src/WebJobs.Script/Binding/ServiceBusScriptBindingProvider.cs

@@ -16,8 +16,6 @@ namespace Microsoft.Azure.WebJobs.Script.Binding
 {
     internal class ServiceBusScriptBindingProvider : ScriptBindingProvider
     {
-        private EventHubConfiguration _eventHubConfiguration;
-
         public ServiceBusScriptBindingProvider(JobHostConfiguration config, JObject hostMetadata, TraceWriter traceWriter)
             : base(config, hostMetadata, traceWriter)
         {
@@ -65,32 +63,10 @@ public override void Initialize()
                 }
             }
 
-            EventProcessorOptions eventProcessorOptions = EventProcessorOptions.DefaultOptions;
-            eventProcessorOptions.MaxBatchSize = 1000;
-            int batchCheckpointFrequency = 1;
-            configSection = (JObject)Metadata.GetValue("eventHub", StringComparison.OrdinalIgnoreCase);
-            if (configSection != null)
-            {
-                if (configSection.TryGetValue("maxBatchSize", StringComparison.OrdinalIgnoreCase, out value))
-                {
-                    eventProcessorOptions.MaxBatchSize = (int)value;
-                }
-
-                if (configSection.TryGetValue("prefetchCount", StringComparison.OrdinalIgnoreCase, out value))
-                {
-                    eventProcessorOptions.PrefetchCount = (int)value;
-                }
-
-                if (configSection.TryGetValue("batchCheckpointFrequency", StringComparison.OrdinalIgnoreCase, out value))
-                {
-                    batchCheckpointFrequency = (int)value;
-                }
-            }
-            _eventHubConfiguration = new EventHubConfiguration(eventProcessorOptions);
-            _eventHubConfiguration.BatchCheckpointFrequency = batchCheckpointFrequency;
+            var eventHubConfiguration = new EventHubConfiguration();
 
             Config.UseServiceBus(serviceBusConfig);
-            Config.UseEventHub(_eventHubConfiguration);
+            Config.UseEventHub(eventHubConfiguration);
         }
 
         public override bool TryResolveAssembly(string assemblyName, out Assembly assembly)

test/WebJobs.Script.Tests/ScriptHostTests.cs

@@ -23,7 +23,9 @@
 using Microsoft.Azure.WebJobs.Script.Description;
 using Microsoft.Azure.WebJobs.Script.Diagnostics;
 using Microsoft.Azure.WebJobs.Script.Eventing;
+using Microsoft.Azure.WebJobs.ServiceBus;
 using Microsoft.Extensions.Logging;
+using Microsoft.ServiceBus.Messaging;
 using Microsoft.WebJobs.Script.Tests;
 using Moq;
 using Newtonsoft.Json.Linq;
@@ -524,6 +526,83 @@ public void ApplyConfiguration_Http()
             Assert.Equal(10, httpConfig.MaxOutstandingRequests);
         }
 
+        [Fact]
+        public void ApplyConfiguration_EventHubs_UsesWebJobsDefaults()
+        {
+            JObject config = new JObject();
+            JObject eventHub = new JObject();
+            config["eventHub"] = eventHub;
+
+            ScriptHostConfiguration scriptConfig = new ScriptHostConfiguration();
+            scriptConfig.HostConfig.HostConfigMetadata = config;
+            TraceWriter traceWriter = new TestTraceWriter(TraceLevel.Verbose);
+
+            var provider = new ServiceBusScriptBindingProvider(scriptConfig.HostConfig, config, traceWriter);
+            provider.Initialize();
+
+            new JobHost(scriptConfig.HostConfig).CreateMetadataProvider(); // will cause extensions to initialize and consume config metadata.
+
+            IExtensionRegistry extensions = scriptConfig.HostConfig.GetService<IExtensionRegistry>();
+            var eventHubConfig = extensions.GetExtensions<IExtensionConfigProvider>().OfType<EventHubConfiguration>().Single();
+
+            // I don't want to update any of the V1 public surface area, so I'll just use reflection for this test.
+            var getOptionsMethod = typeof(EventHubConfiguration)
+                    .GetMethod("GetOptions", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
+
+            Assert.NotNull(getOptionsMethod);
+
+            var eventHubOptions = (EventProcessorOptions)getOptionsMethod.Invoke(eventHubConfig, new object[] { });
+
+            // Now lets find out what the defaults should be
+            var defaultEventHubConfiguration = new EventHubConfiguration();
+            var defaultOptions = (EventProcessorOptions)getOptionsMethod.Invoke(defaultEventHubConfiguration, new object[] { });
+
+            // And verify they match
+            Assert.Equal(defaultOptions.MaxBatchSize, eventHubOptions.MaxBatchSize);
+            Assert.Equal(defaultOptions.PrefetchCount, eventHubOptions.PrefetchCount);
+            Assert.Equal(defaultEventHubConfiguration.BatchCheckpointFrequency, eventHubConfig.BatchCheckpointFrequency);
+        }
+
+        [Fact]
+        public void ApplyConfiguration_EventHubs_UsesCustomConfiguration()
+        {
+            JObject config = new JObject();
+            JObject eventHub = new JObject();
+            config["eventHub"] = eventHub;
+
+            var customBatchSize = 33;
+            var customPrefetchCount = 99;
+            var customCheckpointFrequency = 4;
+
+            eventHub["maxBatchSize"] = customBatchSize;
+            eventHub["prefetchCount"] = customPrefetchCount;
+            eventHub["batchCheckpointFrequency"] = customCheckpointFrequency;
+
+            ScriptHostConfiguration scriptConfig = new ScriptHostConfiguration();
+            scriptConfig.HostConfig.HostConfigMetadata = config;
+            TraceWriter traceWriter = new TestTraceWriter(TraceLevel.Verbose);
+
+            var provider = new ServiceBusScriptBindingProvider(scriptConfig.HostConfig, config, traceWriter);
+            provider.Initialize();
+
+            new JobHost(scriptConfig.HostConfig).CreateMetadataProvider(); // will cause extensions to initialize and consume config metadata.
+
+            IExtensionRegistry extensions = scriptConfig.HostConfig.GetService<IExtensionRegistry>();
+            var eventHubConfig = extensions.GetExtensions<IExtensionConfigProvider>().OfType<EventHubConfiguration>().Single();
+
+            // I don't want to update any of the V1 public surface area, so I'll just use reflection for this test.
+            var getOptionsMethod = typeof(EventHubConfiguration)
+                    .GetMethod("GetOptions", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
+
+            Assert.NotNull(getOptionsMethod);
+
+            var eventHubOptions = (EventProcessorOptions)getOptionsMethod.Invoke(eventHubConfig, new object[] { });
+
+            Assert.Equal(customBatchSize, eventHubOptions.MaxBatchSize);
+            Assert.Equal(customPrefetchCount, eventHubOptions.PrefetchCount);
+            Assert.Equal(customCheckpointFrequency, eventHubConfig.BatchCheckpointFrequency);
+        }
+
         [Fact]
         public void ApplyConfiguration_Blobs()
         {