WIP #552 - Add unit test to repro

Actually, this unit test does not repro the issue.
Frustratingly I can't get it to save the executed workflow
into MongoDB at all.  I see workflow execution logs
being saved, but the instance doesn't go in.

I'm not sure if this is a mistake I'm making or whether
I have found a different bug of some sort.

appveyor.yml

@@ -13,6 +13,9 @@ environment:
 
 version: 2.0.0-preview7.{build}
 
+services:
+  - mongodb
+
 init:
   - cmd: git config --global core.autocrlf true
 

test/integration/Elsa.Core.IntegrationTests/Autofixture/HostBuilderWithElsaSampleWorkflowAndMongoDbAttribute.cs

@@ -0,0 +1,31 @@
+using System.Reflection;
+using AutoFixture;
+using AutoFixture.Xunit2;
+using Elsa.Activities.UserTask.Activities;
+using Elsa.Core.IntegrationTests.Workflows;
+using Elsa.Persistence.MongoDb.Extensions;
+using Elsa.Testing.Shared.AutoFixture.Customizations;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace Elsa.Core.IntegrationTests.Autofixture
+{
+    public class HostBuilderWithElsaSampleWorkflowAndMongoDbAttribute : CustomizeAttribute
+    {
+        public override ICustomization GetCustomization(ParameterInfo parameter)
+        {
+            return new HostBubilderUsingServicesCustomization(services => {
+                services
+                    .AddElsa(elsa => {
+                        elsa.UseMongoDbPersistence(opts => {
+                            opts.ConnectionString = "mongodb://localhost:27017";
+                            opts.Db = "IntegrationTests";
+                        });
+                        elsa.AddActivity<UserTask>();
+                        elsa.AddWorkflow<SampleWorkflow>();
+                    })
+                    ;
+            }, parameter);
+        }
+    }
+}

test/integration/Elsa.Core.IntegrationTests/Elsa.Core.IntegrationTests.csproj

@@ -45,6 +45,7 @@
       <ProjectReference Include="..\..\..\src\activities\Elsa.Activities.Temporal.Common\Elsa.Activities.Temporal.Common.csproj" />
       <ProjectReference Include="..\..\..\src\activities\Elsa.Activities.Temporal.Hangfire\Elsa.Activities.Temporal.Hangfire.csproj" />
       <ProjectReference Include="..\..\..\src\activities\Elsa.Activities.Temporal.Quartz\Elsa.Activities.Temporal.Quartz.csproj" />
+      <ProjectReference Include="..\..\..\src\persistence\Elsa.Persistence.MongoDb\Elsa.Persistence.MongoDb.csproj" />
     </ItemGroup>
 
 </Project>

test/integration/Elsa.Core.IntegrationTests/Persistence/MongoDb/MongoDbIntegrationTests.cs

@@ -0,0 +1,46 @@
+using Xunit;
+using System.Threading.Tasks;
+using Elsa.Core.IntegrationTests.Autofixture;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+using System.Threading;
+using Elsa.Services;
+using Elsa.Core.IntegrationTests.Workflows;
+using Elsa.Persistence;
+using System;
+
+namespace Elsa.Core.IntegrationTests.Persistence.MongoDb
+{
+    public class MongoDbIntegrationTests
+    {
+        [Theory(DisplayName = "A saved workflow instance should be round-trippable without error"), AutoMoqData]
+        public async Task ASavedWorkflowInstanceShouldBeRoundTrippableWithoutError([HostBuilderWithElsaSampleWorkflowAndMongoDbAttribute] IHostBuilder hostBuilder)
+        {
+            hostBuilder.ConfigureServices((ctx, services) => services.AddHostedService<HostedWorkflowRunner>());
+            var host = await hostBuilder.StartAsync();
+        }
+
+        class HostedWorkflowRunner : IHostedService
+        {
+            readonly IWorkflowRunner workflowRunner;
+            readonly IWorkflowInstanceStore instanceStore;
+
+            public async Task StartAsync(CancellationToken cancellationToken)
+            {
+                var instance = await workflowRunner.RunWorkflowAsync<SampleWorkflow>();
+                var retrievedInstance = await instanceStore.FindByIdAsync(instance.Id);
+
+                Assert.NotNull(retrievedInstance);
+                Assert.NotSame(instance, retrievedInstance);
+            }
+
+            public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
+            public HostedWorkflowRunner(IWorkflowRunner workflowRunner, IWorkflowInstanceStore instanceStore)
+            {
+                this.workflowRunner = workflowRunner ?? throw new System.ArgumentNullException(nameof(workflowRunner));
+                this.instanceStore = instanceStore ?? throw new System.ArgumentNullException(nameof(instanceStore));
+            }
+        }
+    }
+}

test/integration/Elsa.Core.IntegrationTests/Workflows/SampleWorkflow.cs

@@ -0,0 +1,20 @@
+using Elsa.Activities.UserTask.Activities;
+using Elsa.Builders;
+using Elsa.Activities.ControlFlow;
+
+namespace Elsa.Core.IntegrationTests.Workflows
+{
+    public class SampleWorkflow : IWorkflow
+    {
+        public static readonly object Result = new object();
+
+        public void Build(IWorkflowBuilder builder)
+        {
+            builder
+                .StartWith<UserTask>(setup: s => {
+                    s.Set(x => x.Actions, c => new [] { "Foo", "Bar" });
+                })
+                .Finish(x => x.WithOutput(Result));
+        }
+    }
+}