WIP #728 - Make WorkflowBurst default behaviour

In the comments to #728 it was suggested that
WorkflowBurst persistence behaviour was a more
sane default.

src/core/Elsa.Abstractions/Models/WorkflowPersistenceBehavior.cs

@@ -6,16 +6,22 @@ namespace Elsa.Models
     [JsonConverter(typeof(StringEnumConverter))]
     public enum WorkflowPersistenceBehavior
     {
+        // TODO: Consider a new service to "get the default persistence behaviour".
+        // Currently it is set to WorkflowBurst implicitly because it is the default
+        // for the enum type.  This would be more clear if explicit.
+        // This includes altering all locations which need a default persistence
+        // behaviour though.
+
+        /// <summary>
+        /// Workflow instances are persisted after the workflow completed a burst of execution.
+        /// </summary>
+        WorkflowBurst = 0,
+
         /// <summary>
         /// Workflow instances are persisted only when being suspended. 
         /// </summary>
         Suspended,
         
-        /// <summary>
-        /// Workflow instances are persisted after the workflow completed a burst of execution.
-        /// </summary>
-        WorkflowBurst,
-        
         /// <summary>
         /// Workflow instances are persisted after the workflow executed scheduled activities.
         /// </summary>

test/unit/Elsa.UnitTests/Services/WorkflowBuilderTests.cs

@@ -0,0 +1,29 @@
+using System;
+using AutoFixture.Xunit2;
+using Elsa.Builders;
+using Elsa.Models;
+using Elsa.Testing.Shared.AutoFixture.Attributes;
+using Xunit;
+
+namespace Elsa.Services
+{
+    public class WorkflowBuilderTests
+    {
+        [Theory(DisplayName = "The Build method should return a workflow blueprint with the WorkflowBurst persistence behaviour if no behaviour was specified"), AutoMoqData]
+        public void BuildShouldReturnWorkflowBlueprintWithWorkflowBurstPersistenceBehaviourIfNoBehaviourSpecified([AutofixtureServiceProvider, Frozen] IServiceProvider serviceProvider,
+                                                                                                                  WorkflowBuilder sut,
+                                                                                                                  string idPrefix)
+        {
+            var workflow = new NoOpWorkflow();
+
+            var blueprint = sut.Build(workflow, idPrefix);
+
+            Assert.Equal(WorkflowPersistenceBehavior.WorkflowBurst, blueprint.PersistenceBehavior);
+        }
+
+        class NoOpWorkflow : IWorkflow
+        {
+            public void Build(IWorkflowBuilder builder) { }
+        }
+    }
+}