System.Runtime.Caching meets Projac.Connector

KickIt.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Caching;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using KellermanSoftware.CompareNetObjects;
using Newtonsoft.Json.Linq;
using NUnit.Framework;
using Projac.Connector;
using Projac.Connector.Testing;

namespace KickIt
{
    //Events
    public class DonationCollectionStarted
    {
        public readonly Guid DonationCollectionId;
        public readonly Guid DonationId;
        public readonly string ReferralCode;
        public readonly DateTimeOffset StartDateTime;

        public DonationCollectionStarted(Guid donationCollectionId, Guid donationId, string referralCode, DateTimeOffset startDateTime)
        {
            DonationCollectionId = donationCollectionId;
            DonationId = donationId;
            ReferralCode = referralCode;
            StartDateTime = startDateTime;
        }
    }

    public class DonationToSuspendedCauseAttempted
    {
        public readonly Guid DonationCollectionId;
        public readonly Guid DonationId;

        public DonationToSuspendedCauseAttempted(Guid donationCollectionId, Guid donationId)
        {
            DonationCollectionId = donationCollectionId;
            DonationId = donationId;
        }
    }

    //Specs
    [TestFixture]
    public class DonationProjectionSpecs
    {
        [Test]
        public Task when_a_donation_collection_started()
        {
            return MemoryCacheProjection.For(new DonationProjection(MemoryAdditionalDataProvider.Empty)).
                Given(
                    new DonationCollectionStarted(
                        new Guid("438AEA16-54A2-4C76-B82E-97563C475D5E"),
                        new Guid("69AB3034-C7DD-4629-A1F8-97AF099C8556"),
                        "BLA-BLA",
                        DateTimeOffset.Parse("2015-12-15 11:14:01.088"))).
                Expect(new CacheItem(
                    "69AB3034-C7DD-4629-A1F8-97AF099C8556".ToLower(),
                    new DonationDataModel
                    {
                        DonationCollectionId = new Guid("438AEA16-54A2-4C76-B82E-97563C475D5E"),
                        DonationStartedTime = DateTimeOffset.Parse("2015-12-15 11:14:01.088"),
                        ReferralCode = "BLA-BLA",
                        AdditionalData = null,
                        Invalid = false,
                        Reason = null
                    }));
        }

        [Test]
        public Task when_a_donation_to_a_suspended_cause_was_attempted()
        {
            return MemoryCacheProjection.For(new DonationProjection(MemoryAdditionalDataProvider.Empty)).
                Given(
                    new DonationCollectionStarted(
                        new Guid("438AEA16-54A2-4C76-B82E-97563C475D5E"),
                        new Guid("69AB3034-C7DD-4629-A1F8-97AF099C8556"),
                        "BLA-BLA",
                        DateTimeOffset.Parse("2015-12-15 11:14:01.088")),
                    new DonationToSuspendedCauseAttempted(
                        new Guid("438AEA16-54A2-4C76-B82E-97563C475D5E"),
                        new Guid("69AB3034-C7DD-4629-A1F8-97AF099C8556"))).
                Expect(new CacheItem(
                    "69AB3034-C7DD-4629-A1F8-97AF099C8556".ToLower(),
                    new DonationDataModel
                    {
                        DonationCollectionId = new Guid("438AEA16-54A2-4C76-B82E-97563C475D5E"),
                        DonationStartedTime = DateTimeOffset.Parse("2015-12-15 11:14:01.088"),
                        ReferralCode = "BLA-BLA",
                        AdditionalData = null,
                        Invalid = true,
                        Reason = "Can't donate to a suspended cause"
                    }));
        }
    }

    //Data Model
    public class DonationDataModel
    {
        public Guid DonationCollectionId { get; set; }
        public string ReferralCode { get; set; }
        public DateTimeOffset DonationStartedTime { get; set; }
        public string AdditionalData { get; set; }

        public bool Invalid { get; set; }
        public string Reason { get; set; }
    }

    //Projection
    public class DonationProjection : ConnectedProjection<MemoryCache>
    {
        public DonationProjection(IAdditionalDataProvider additionalDataProvider)
        {
            When<DonationCollectionStarted>(
                async (cache, message) =>
                {
                    var additionalData = await additionalDataProvider.GetAsync(message.DonationCollectionId);
                    cache.Add(
                        new CacheItem(
                            message.DonationId.ToString(),
                            new DonationDataModel
                            {
                                DonationCollectionId = message.DonationCollectionId,
                                DonationStartedTime = message.StartDateTime,
                                ReferralCode = message.ReferralCode,
                                AdditionalData = additionalData,
                                Invalid = false,
                                Reason = null
                            }),
                        new CacheItemPolicy
                        {
                            AbsoluteExpiration = ObjectCache.InfiniteAbsoluteExpiration
                        });
                });

            WhenSync<DonationToSuspendedCauseAttempted>(
                (cache, message) =>
                {
                    var item = cache.GetCacheItem(message.DonationId.ToString());
                    if (item != null)
                    {
                        var model = (DonationDataModel)item.Value;
                        model.Invalid = true;
                        model.Reason = "Can't donate to a suspended cause";
                    }
                });
        }
    }

    //Services
    public interface IAdditionalDataProvider
    {
        Task<string> GetAsync(Guid donationId);
    }

    public class MemoryAdditionalDataProvider : IAdditionalDataProvider
    {
        public static readonly IAdditionalDataProvider Empty =
            new MemoryAdditionalDataProvider(new Dictionary<Guid, string>());

        private readonly IReadOnlyDictionary<Guid, string> _store;

        public MemoryAdditionalDataProvider(IReadOnlyDictionary<Guid, string> store)
        {
            if (store == null)
                throw new ArgumentNullException("store");
            _store = store;
        }

        public Task<string> GetAsync(Guid donationId)
        {
            string data;
            return Task.FromResult(_store.TryGetValue(donationId, out data) ? data : null);
        }
    }

    //Infrastructure

    public static class MemoryCacheProjection
    {
        public static ConnectedProjectionScenario<MemoryCache> For(ConnectedProjectionHandler<MemoryCache>[] handlers)
        {
            return new ConnectedProjectionScenario<MemoryCache>(
                ConcurrentResolve.WhenEqualToHandlerMessageType(handlers)
                );
        }

        public static Task ExpectNone(this ConnectedProjectionScenario<MemoryCache> scenario)
        {
            return scenario.
                Verify(cache =>
                {
                    if (cache.GetCount() != 0)
                    {
                        return Task.FromResult(
                            VerificationResult.Fail(
                                string.Format("Expected no cache items, but found {0} cache item(s) ({1}).",
                                    cache.GetCount(),
                                    string.Join(",", cache.Select(pair => pair.Key)))));
                    }
                    return Task.FromResult(VerificationResult.Pass());
                }).
                Assert();
        }

        public static async Task Assert(this ConnectedProjectionTestSpecification<MemoryCache> specification)
        {
            if (specification == null)
                throw new ArgumentNullException("specification");
            using (var cache = new MemoryCache(new Random().Next().ToString()))
            {
                await new ConnectedProjector<MemoryCache>(specification.Resolver).
                    ProjectAsync(cache, specification.Messages);
                var result = await specification.Verification(cache, CancellationToken.None);
                if (result.Failed)
                {
                    throw new AssertionException(result.Message);
                }
            }
        }

        public static Task Expect(this ConnectedProjectionScenario<MemoryCache> scenario, params CacheItem[] items)
        {
            if (items == null)
                throw new ArgumentNullException("items");

            if (items.Length == 0)
            {
                return scenario.ExpectNone();
            }

            return scenario.
                Verify(cache =>
                {
                    if (cache.GetCount() != items.Length)
                    {
                        if (cache.GetCount() == 0)
                        {
                            return Task.FromResult(
                                VerificationResult.Fail(
                                    string.Format("Expected {0} cache item(s), but found 0 cache items.",
                                        items.Length)));
                        }

                        return Task.FromResult(
                            VerificationResult.Fail(
                                string.Format("Expected {0} cache item(s), but found {1} cache item(s) ({2}).",
                                    items.Length,
                                    cache.GetCount(),
                                    string.Join(",", cache.Select(pair => pair.Key)))));
                    }
                    if (!cache.Select(pair => cache.GetCacheItem(pair.Key)).SequenceEqual(items, new CacheItemEqualityComparer()))
                    {
                        var builder = new StringBuilder();
                        builder.AppendLine("Expected the following cache items:");
                        foreach (var expectedItem in items)
                        {
                            builder.AppendLine(expectedItem.Key + ": " + JToken.FromObject(expectedItem.Value).ToString());
                        }
                        builder.AppendLine();
                        builder.AppendLine("But found the following cache items:");
                        foreach (var actualItem in cache)
                        {
                            builder.AppendLine(actualItem.Key + ": " + JToken.FromObject(actualItem.Value).ToString());
                        }
                        return Task.FromResult(VerificationResult.Fail(builder.ToString()));
                    }
                    return Task.FromResult(VerificationResult.Pass());
                }).
                Assert();
        }
    }

    public class CacheItemEqualityComparer : IEqualityComparer<CacheItem>
    {
        public bool Equals(CacheItem x, CacheItem y)
        {
            if (x == null && y == null) return true;
            if (x == null || y == null) return false;
            return x.Key.Equals(y.Key) &&
                   new CompareLogic().Compare(x.Value, y.Value).AreEqual;
        }

        public int GetHashCode(CacheItem obj)
        {
            throw new NotSupportedException();
        }
    }
}