Fix transaction failures for predefined temp_id of new entities (#44)

* Added transaction tests for predefined temp_id as discussed in #43

* Added a check in command service for existing temp_id before creating a new one.
Which should fix failing tests for predefined temp_id transactions.

* Used `Guid.Empty` instead of `default` for better readability.

* Updated transaction tests with `async/await`.

Author: AhmedZaki99

src/Todoist.Net.Tests/Services/TransactionTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 using Todoist.Net.Models;
 using Todoist.Net.Tests.Extensions;
@@ -44,5 +45,83 @@ public void CreateProjectAndCreateNote_Success()
 
             deleteTransaction.CommitAsync().Wait();
         }
+
+        [Fact]
+        [Trait(Constants.TraitName, Constants.IntegrationFreeTraitValue)]
+        public async Task CreateProjectAndCreateItem_Success()
+        {
+            var client = TodoistClientFactory.Create(_outputHelper);
+
+            var transaction = client.CreateTransaction();
+
+            var project = new Project("Shopping List");
+            var projectId = await transaction.Project.AddAsync(project);
+
+            var item = new Item("Buy milk")
+            {
+                ProjectId = projectId
+            };
+            await transaction.Items.AddAsync(item);
+
+            await transaction.CommitAsync();
+
+            Assert.False(string.IsNullOrEmpty(project.Id.PersistentId));
+            Assert.False(string.IsNullOrEmpty(item.Id.PersistentId));
+
+
+            var itemInfo = await client.Items.GetAsync(item.Id);
+
+            Assert.Equal(itemInfo.Item.Content, item.Content);
+            Assert.Equal(itemInfo.Project.Name, project.Name);
+            Assert.Equal(itemInfo.Project.Id.PersistentId, project.Id.PersistentId);
+
+
+            await client.Projects.DeleteAsync(project.Id);
+
+            var projects = await client.Projects.GetAsync();
+
+            Assert.DoesNotContain(projects, p => p.Id.PersistentId == project.Id.PersistentId);
+        }
+
+        [Fact]
+        [Trait(Constants.TraitName, Constants.IntegrationFreeTraitValue)]
+        public async Task CreateProjectAndCreateItemWithPredefinedTempId_Success()
+        {
+            var client = TodoistClientFactory.Create(_outputHelper);
+
+            var project = new Project("Shopping List")
+            {
+                Id = new ComplexId(Guid.NewGuid()) // predefined temp id
+            };
+            var item = new Item("Buy milk")
+            {
+                ProjectId = project.Id // predefined temp id
+            };
+
+            var transaction = client.CreateTransaction();
+
+            await transaction.Project.AddAsync(project);
+            await transaction.Items.AddAsync(item);
+
+            await transaction.CommitAsync();
+
+            Assert.False(string.IsNullOrEmpty(project.Id.PersistentId));
+            Assert.False(string.IsNullOrEmpty(item.Id.PersistentId));
+
+
+            var itemInfo = await client.Items.GetAsync(item.Id);
+
+            Assert.Equal(itemInfo.Item.Content, item.Content);
+            Assert.Equal(itemInfo.Project.Name, project.Name);
+            Assert.Equal(itemInfo.Project.Id.PersistentId, project.Id.PersistentId);
+
+
+            await client.Projects.DeleteAsync(project.Id);
+
+            var projects = await client.Projects.GetAsync();
+
+            Assert.DoesNotContain(projects, p => p.Id.PersistentId == project.Id.PersistentId);
+        }
+
     }
 }

src/Todoist.Net/Services/CommandServiceBase.cs

@@ -26,7 +26,11 @@ protected CommandServiceBase(ICollection<Command> queue)
 
         internal Command CreateAddCommand<T>(CommandType commandType, T entity) where T : BaseEntity
         {
-            var tempId = Guid.NewGuid();
+            var tempId = entity.Id.TempId;
+            if (tempId == Guid.Empty)
+            {
+                tempId = Guid.NewGuid();
+            }
             entity.Id = tempId;
 
             return new Command(commandType, entity, tempId);