public async Task StopAsyncCallsPartitionProcessorCloseAsyncWithShutdownReason()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(2))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);
                var closeCalls       = new ConcurrentDictionary <string, int>();
                var stopReasons      = new ConcurrentDictionary <string, ProcessingStoppedReason>();

                // Create the event processor manager to manage our event processors.

                var eventProcessorManager = new EventProcessorManager
                                            (
                    EventHubConsumerClient.DefaultConsumerGroupName,
                    connectionString,
                    onStop: eventArgs =>
                {
                    closeCalls.AddOrUpdate(eventArgs.PartitionId, 1, (partitionId, value) => value + 1);
                    stopReasons[eventArgs.PartitionId] = eventArgs.Reason;
                }
                                            );

                eventProcessorManager.AddEventProcessors(1);

                // Start the event processors.

                await eventProcessorManager.StartAllAsync();

                // Make sure the event processors have enough time to stabilize.

                await eventProcessorManager.WaitStabilization();

                // CloseAsync should have not been called when constructing the event processor or during processing initialization.

                Assert.That(closeCalls.Keys, Is.Empty);

                // Stop the event processors.

                await eventProcessorManager.StopAllAsync();

                // Validate results.

                await using (var producer = new EventHubProducerClient(connectionString))
                {
                    var partitionIds = await producer.GetPartitionIdsAsync();

                    foreach (var partitionId in partitionIds)
                    {
                        Assert.That(closeCalls.TryGetValue(partitionId, out var calls), Is.True, $"{ partitionId }: CloseAsync should have been called.");
                        Assert.That(calls, Is.EqualTo(1), $"{ partitionId }: CloseAsync should have been called only once.");

                        Assert.That(stopReasons.TryGetValue(partitionId, out ProcessingStoppedReason reason), Is.True, $"{ partitionId }: processing stopped reason should have been set.");
                        Assert.That(reason, Is.EqualTo(ProcessingStoppedReason.Shutdown), $"{ partitionId }: unexpected processing stopped reason.");
                    }

                    Assert.That(closeCalls.Keys.Count, Is.EqualTo(partitionIds.Count()));
                }
            }
        }
        public async Task PartitionDistributionIsEvenAfterLoadBalancing(int partitions, int eventProcessors)
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(partitions))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    ConcurrentDictionary <string, int> ownedPartitionsCount = new ConcurrentDictionary <string, int>();

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString
                        // TODO: fix test. OwnerIdentifier is not accessible anymore.
                        // onInitialize: eventArgs =>
                        //     ownedPartitionsCount.AddOrUpdate(eventArgs.Context.OwnerIdentifier, 1, (ownerId, value) => value + 1),
                        // onStop: eventArgs =>
                        //     ownedPartitionsCount.AddOrUpdate(eventArgs.Context.OwnerIdentifier, 0, (ownerId, value) => value - 1)
                                                );

                    eventProcessorManager.AddEventProcessors(eventProcessors);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize.

                    await eventProcessorManager.WaitStabilization();

                    // Take a snapshot of the current partition balancing status.

                    IEnumerable <int> ownedPartitionsCountSnapshot = ownedPartitionsCount.ToArray().Select(kvp => kvp.Value);

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.

                    var minimumOwnedPartitionsCount = partitions / eventProcessors;
                    var maximumOwnedPartitionsCount = minimumOwnedPartitionsCount + 1;

                    foreach (var count in ownedPartitionsCountSnapshot)
                    {
                        Assert.That(count, Is.InRange(minimumOwnedPartitionsCount, maximumOwnedPartitionsCount));
                    }

                    Assert.That(ownedPartitionsCountSnapshot.Sum(), Is.EqualTo(partitions));
                }
            }
        }
        public async Task StartAsyncCallsPartitionProcessorInitializeAsync()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(2))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);
                var consumerGroup    = EventHubConsumerClient.DefaultConsumerGroupName;

                await using (var consumer = new EventHubConsumerClient(consumerGroup, connectionString))
                {
                    var initializeCalls = new ConcurrentDictionary <string, int>();

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        consumerGroup,
                        connectionString,
                        onInitialize: eventArgs =>
                        initializeCalls.AddOrUpdate(eventArgs.PartitionId, 1, (partitionId, value) => value + 1)
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // InitializeAsync should have not been called when constructing the event processors.

                    Assert.That(initializeCalls.Keys, Is.Empty);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize.

                    await eventProcessorManager.WaitStabilization();

                    // Validate results before calling stop.  This way, we can make sure the initialize calls were
                    // triggered by start.

                    var partitionIds = await consumer.GetPartitionIdsAsync();

                    foreach (var partitionId in partitionIds)
                    {
                        Assert.That(initializeCalls.TryGetValue(partitionId, out var calls), Is.True, $"{ partitionId }: InitializeAsync should have been called.");
                        Assert.That(calls, Is.EqualTo(1), $"{ partitionId }: InitializeAsync should have been called only once.");
                    }

                    Assert.That(initializeCalls.Keys.Count, Is.EqualTo(partitionIds.Count()));

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();
                }
            }
        }
        public async Task StopAsyncDoesNothingWhenEventProcessorIsNotRunning()
        {
            var partitions = 1;

            await using (EventHubScope scope = await EventHubScope.CreateAsync(partitions))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    int closeCallsCount = 0;

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        onStop: eventArgs =>
                        Interlocked.Increment(ref closeCallsCount)
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Calling StopAsync before starting the event processors shouldn't have any effect.

                    Assert.That(async() => await eventProcessorManager.StopAllAsync(), Throws.Nothing);

                    Assert.That(closeCallsCount, Is.EqualTo(0));

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // We should be able to call StopAsync again without getting an exception.

                    Assert.That(async() => await eventProcessorManager.StopAllAsync(), Throws.Nothing);

                    // Validate results.

                    Assert.That(closeCallsCount, Is.EqualTo(partitions));
                }
            }
        }
        public async Task PartitionProcessorProcessEventsAsyncIsCalledWithNoEvents()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(1))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    var receivedEvents = new ConcurrentBag <EventData>();

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        onProcessEvent: eventArgs =>
                        receivedEvents.Add(eventArgs.Data)
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.

                    Assert.That(receivedEvents, Is.Not.Empty);
                    Assert.That(receivedEvents.Any(eventData => eventData != null), Is.False);
                }
            }
        }
        public async Task EventProcessorWaitsMaximumWaitTimeForEvents(int maximumWaitTimeInSecs)
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(2))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    var timestamps = new ConcurrentDictionary <string, List <DateTimeOffset> >();

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        clientOptions: new EventProcessorClientOptions {
                        MaximumWaitTime = TimeSpan.FromSeconds(maximumWaitTimeInSecs)
                    },
                        onInitialize: eventArgs =>
                        timestamps.TryAdd(eventArgs.PartitionId, new List <DateTimeOffset> {
                        DateTimeOffset.UtcNow
                    }),
                        onProcessEvent: eventArgs =>
                        timestamps.AddOrUpdate
                        (
                            // The key already exists, so the 'addValue' factory will never be called.

                            eventArgs.Partition.PartitionId,
                            partitionId => null,
                            (partitionId, list) =>
                    {
                        list.Add(DateTimeOffset.UtcNow);
                        return(list);
                    }
                        )
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.

                    foreach (KeyValuePair <string, List <DateTimeOffset> > kvp in timestamps)
                    {
                        var partitionId = kvp.Key;
                        List <DateTimeOffset> partitionTimestamps = kvp.Value;

                        Assert.That(partitionTimestamps.Count, Is.GreaterThan(1), $"{ partitionId }: more time stamp samples were expected.");

                        for (int index = 1; index < partitionTimestamps.Count; index++)
                        {
                            var elapsedTime = partitionTimestamps[index].Subtract(partitionTimestamps[index - 1]).TotalSeconds;

                            Assert.That(elapsedTime, Is.GreaterThan(maximumWaitTimeInSecs - 0.1), $"{ partitionId }: elapsed time between indexes { index - 1 } and { index } was too short.");
                            Assert.That(elapsedTime, Is.LessThan(maximumWaitTimeInSecs + 5), $"{ partitionId }: elapsed time between indexes { index - 1 } and { index } was too long.");

                            ++index;
                        }
                    }
                }
            }
        }
        public async Task EventProcessorCanReceiveFromSpecifiedInitialEventPosition()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(2))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    int receivedEventsCount = 0;

                    // Send some events.

                    var            expectedEventsCount = 20;
                    DateTimeOffset enqueuedTime;

                    await using (var producer = new EventHubProducerClient(connection))
                    {
                        // Send a few dummy events.  We are not expecting to receive these.

                        using (var dummyBatch = await producer.CreateBatchAsync())
                        {
                            for (int i = 0; i < 30; i++)
                            {
                                dummyBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("I'm dummy.")));
                            }

                            await producer.SendAsync(dummyBatch);
                        }

                        // Wait a reasonable amount of time so the events are able to reach the service.

                        await Task.Delay(1000);

                        // Send the events we expect to receive.

                        enqueuedTime = DateTimeOffset.UtcNow;

                        using (var dummyBatch = await producer.CreateBatchAsync())
                        {
                            for (int i = 0; i < expectedEventsCount; i++)
                            {
                                dummyBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("I'm dummy.")));
                            }

                            await producer.SendAsync(dummyBatch);
                        }
                    }

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        onInitialize: eventArgs =>
                        eventArgs.DefaultStartingPosition = EventPosition.FromEnqueuedTime(enqueuedTime),
                        onProcessEvent: eventArgs =>
                    {
                        if (eventArgs.Data != null)
                        {
                            Interlocked.Increment(ref receivedEventsCount);
                        }
                    }
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize and receive events.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.

                    Assert.That(receivedEventsCount, Is.EqualTo(expectedEventsCount));
                }
            }
        }
        public async Task PartitionProcessorCanCreateACheckpoint()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(1))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    // Send some events.

                    EventData lastEvent;

                    await using (var producer = new EventHubProducerClient(connection))
                        await using (var consumer = new EventHubConsumerClient(EventHubConsumerClient.DefaultConsumerGroupName, connectionString))
                        {
                            // Send a few events.  We are only interested in the last one of them.

                            var dummyEventsCount = 10;

                            using (var dummyBatch = await producer.CreateBatchAsync())
                            {
                                for (int i = 0; i < dummyEventsCount; i++)
                                {
                                    dummyBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("I'm dummy.")));
                                }

                                await producer.SendAsync(dummyBatch);
                            }

                            // Receive the events; because there is some non-determinism in the messaging flow, the
                            // sent events may not be immediately available.  Allow for a small number of attempts to receive, in order
                            // to account for availability delays.

                            var receivedEvents = new List <EventData>();
                            var index          = 0;

                            while ((receivedEvents.Count < dummyEventsCount) && (++index < ReceiveRetryLimit))
                            {
                                Assert.Fail("Convert to iterator.");
                                //receivedEvents.AddRange(await receiver.ReceiveAsync(dummyEventsCount + 10, TimeSpan.FromMilliseconds(25)));
                            }

                            Assert.That(receivedEvents.Count, Is.EqualTo(dummyEventsCount));

                            lastEvent = receivedEvents.Last();
                        }

                    // Create a partition manager so we can retrieve the created checkpoint from it.

                    var partitionManager = new MockCheckPointStorage();

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        partitionManager,
                        onProcessEvent: eventArgs =>
                    {
                        if (eventArgs.Data != null)
                        {
                            eventArgs.UpdateCheckpointAsync();
                        }
                    }
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize and receive events.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.

                    IEnumerable <PartitionOwnership> ownershipEnumerable = await partitionManager.ListOwnershipAsync(connection.FullyQualifiedNamespace, connection.EventHubName, EventHubConsumerClient.DefaultConsumerGroupName);

                    Assert.That(ownershipEnumerable, Is.Not.Null);
                    Assert.That(ownershipEnumerable.Count, Is.EqualTo(1));
                }
            }
        }
        public async Task EventProcessorCanReceiveFromCheckpointedEventPosition()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(1))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    string partitionId;
                    int    receivedEventsCount = 0;

                    // Send some events.

                    var  expectedEventsCount        = 20;
                    long?checkpointedSequenceNumber = default;

                    await using (var producer = new EventHubProducerClient(connectionString))
                        await using (var consumer = new EventHubConsumerClient(EventHubConsumerClient.DefaultConsumerGroupName, connection))
                        {
                            partitionId = (await consumer.GetPartitionIdsAsync()).First();

                            // Send a few dummy events.  We are not expecting to receive these.

                            var dummyEventsCount = 30;

                            using (var dummyBatch = await producer.CreateBatchAsync())
                            {
                                for (int i = 0; i < dummyEventsCount; i++)
                                {
                                    dummyBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("I'm dummy.")));
                                }

                                await producer.SendAsync(dummyBatch);
                            }

                            // Receive the events; because there is some non-determinism in the messaging flow, the
                            // sent events may not be immediately available.  Allow for a small number of attempts to receive, in order
                            // to account for availability delays.

                            var receivedEvents = new List <EventData>();
                            var index          = 0;

                            while ((receivedEvents.Count < dummyEventsCount) && (++index < ReceiveRetryLimit))
                            {
                                Assert.Fail("Convert to iterator");
                                //receivedEvents.AddRange(await receiver.ReceiveAsync(dummyEventsCount + 10, TimeSpan.FromMilliseconds(25)));
                            }

                            Assert.That(receivedEvents.Count, Is.EqualTo(dummyEventsCount));

                            checkpointedSequenceNumber = receivedEvents.Last().SequenceNumber;

                            // Send the events we expect to receive.

                            using (var dummyBatch = await producer.CreateBatchAsync())
                            {
                                for (int i = 0; i < expectedEventsCount; i++)
                                {
                                    dummyBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("I'm dummy.")));
                                }

                                await producer.SendAsync(dummyBatch);
                            }
                        }

                    // Create a partition manager and add an ownership with a checkpoint in it.

                    var partitionManager = new MockCheckPointStorage();

                    await partitionManager.ClaimOwnershipAsync(new List <PartitionOwnership>()
                    {
                        new PartitionOwnership(connection.FullyQualifiedNamespace, connection.EventHubName,
                                               EventHubConsumerClient.DefaultConsumerGroupName, "ownerIdentifier", partitionId,
                                               lastModifiedTime: DateTimeOffset.UtcNow)
                    });

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        partitionManager,
                        onProcessEvent: eventArgs =>
                    {
                        if (eventArgs.Data != null)
                        {
                            Interlocked.Increment(ref receivedEventsCount);
                        }
                    }
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize and receive events.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.

                    Assert.That(receivedEventsCount, Is.EqualTo(expectedEventsCount));
                }
            }
        }
        public async Task EventProcessorCanStartAgainAfterStopping()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(2))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    int receivedEventsCount = 0;

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        onProcessEvent: eventArgs =>
                    {
                        if (eventArgs.Data != null)
                        {
                            Interlocked.Increment(ref receivedEventsCount);
                        }
                    }
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Send some events.

                    var expectedEventsCount = 20;

                    await using (var producer = new EventHubProducerClient(connection))
                    {
                        using (var dummyBatch = await producer.CreateBatchAsync())
                        {
                            for (int i = 0; i < expectedEventsCount; i++)
                            {
                                dummyBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("I'm dummy.")));
                            }

                            await producer.SendAsync(dummyBatch);
                        }
                    }

                    // We'll start and stop the event processors twice.  This way, we can assert they will behave
                    // the same way both times, reprocessing all events in the second run.

                    for (int i = 0; i < 2; i++)
                    {
                        receivedEventsCount = 0;

                        // Start the event processors.

                        await eventProcessorManager.StartAllAsync();

                        // Make sure the event processors have enough time to stabilize and receive events.

                        await eventProcessorManager.WaitStabilization();

                        // Stop the event processors.

                        await eventProcessorManager.StopAllAsync();

                        // Validate results.

                        Assert.That(receivedEventsCount, Is.EqualTo(expectedEventsCount), $"Events should match in iteration { i + 1 }.");
                    }
                }
            }
        }
        public async Task PartitionProcessorProcessEventsAsyncReceivesAllEvents()
        {
            await using (EventHubScope scope = await EventHubScope.CreateAsync(2))
            {
                var connectionString = TestEnvironment.BuildConnectionStringForEventHub(scope.EventHubName);

                await using (var connection = new EventHubConnection(connectionString))
                {
                    var allReceivedEvents = new ConcurrentDictionary <string, List <EventData> >();

                    // Create the event processor manager to manage our event processors.

                    var eventProcessorManager = new EventProcessorManager
                                                (
                        EventHubConsumerClient.DefaultConsumerGroupName,
                        connectionString,
                        onProcessEvent: eventArgs =>
                    {
                        if (eventArgs.Data != null)
                        {
                            allReceivedEvents.AddOrUpdate
                            (
                                eventArgs.Partition.PartitionId,
                                partitionId => new List <EventData>()
                            {
                                eventArgs.Data
                            },
                                (partitionId, list) =>
                            {
                                list.Add(eventArgs.Data);
                                return(list);
                            }
                            );
                        }
                    }
                                                );

                    eventProcessorManager.AddEventProcessors(1);

                    // Send some events.

                    string[] partitionIds;
                    var      expectedEvents = new Dictionary <string, List <EventData> >();

                    await using (var producer = new EventHubProducerClient(connection))
                    {
                        partitionIds = await producer.GetPartitionIdsAsync();

                        foreach (var partitionId in partitionIds)
                        {
                            // Send a similar set of events for every partition.

                            using (var partitionBatch = await producer.CreateBatchAsync(new CreateBatchOptions {
                                PartitionId = partitionId
                            }))
                            {
                                expectedEvents[partitionId] = new List <EventData>
                                {
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: event processor tests are so long.")),
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: there are so many of them.")),
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: will they ever end?")),
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: let's add a few more messages.")),
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: this is a monologue.")),
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: loneliness is what I feel.")),
                                    new EventData(Encoding.UTF8.GetBytes($"{ partitionId }: the end has come."))
                                };

                                foreach (var expectedEvent in expectedEvents[partitionId])
                                {
                                    partitionBatch.TryAdd(expectedEvent);
                                }

                                await producer.SendAsync(partitionBatch);
                            }
                        }
                    }

                    // Start the event processors.

                    await eventProcessorManager.StartAllAsync();

                    // Make sure the event processors have enough time to stabilize and receive events.

                    await eventProcessorManager.WaitStabilization();

                    // Stop the event processors.

                    await eventProcessorManager.StopAllAsync();

                    // Validate results.  Make sure we received every event with the correct partition context,
                    // in the order they were sent.

                    foreach (var partitionId in partitionIds)
                    {
                        Assert.That(allReceivedEvents.TryGetValue(partitionId, out List <EventData> partitionReceivedEvents), Is.True, $"{ partitionId }: there should have been a set of events received.");
                        Assert.That(partitionReceivedEvents.Count, Is.EqualTo(expectedEvents[partitionId].Count), $"{ partitionId }: amount of received events should match.");

                        var index = 0;

                        foreach (EventData receivedEvent in partitionReceivedEvents)
                        {
                            Assert.That(receivedEvent.IsEquivalentTo(expectedEvents[partitionId][index]), Is.True, $"{ partitionId }: the received event at index { index } did not match the sent set of events.");
                            ++index;
                        }
                    }

                    Assert.That(allReceivedEvents.Keys.Count, Is.EqualTo(partitionIds.Count()));
                }
            }
        }