Refactor message service and move tests to Application.Tests

Renamed IMessageService to IMessageCommandService and updated all usages accordingly. Moved and renamed test files from Govor.API.Tests to the new Govor.Application.Tests project, updating namespaces to match. Refactored message-related services and controllers to use the new naming and structure. Added Govor.Application.Tests project to the solution.

Govor.Application.Tests/Services/UserGroupsServiceTests.cs

@@ -0,0 +1,70 @@
+using AutoFixture;
+using Govor.Application.Interfaces;
+using Govor.Application.Services;
+using Govor.Core.Models;
+using Govor.Core.Repositories.Groups;
+using Govor.Data.Repositories.Exceptions;
+using Moq;
+
+namespace Govor.Application.Tests.Services;
+
+[TestFixture]
+public class UserGroupsServiceTests
+{
+    private Fixture _fixture;
+    private Mock<IGroupsRepository> _repositoryMock;
+    private IUserGroupsService _service;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _fixture = new Fixture();
+
+        _fixture.Behaviors
+            .OfType<ThrowingRecursionBehavior>()
+            .ToList()
+            .ForEach(b => _fixture.Behaviors.Remove(b));
+
+        _fixture.Behaviors.Add(new OmitOnRecursionBehavior());
+        
+        _repositoryMock = new Mock<IGroupsRepository>();
+        
+        _service = new UserGroupsService(_repositoryMock.Object);
+    }
+
+    [Test]
+    public async Task GetUserGroups_ShouldReturnAllUserGroups()
+    {
+        // Arrange 
+        var chats = _fixture.CreateMany<ChatGroup>();
+        var userId = chats.First().Members.First().Id;
+
+        _repositoryMock.Setup(r => r.GetByUserIdAsync(userId))
+            .ReturnsAsync([chats.First()]);
+        
+        // Act 
+        var result = await _service.GetUserGroupsAsync(userId);
+        
+        // Assert 
+        Assert.That(result, Is.Not.Null);
+        Assert.That(result.Count(), Is.EqualTo(1));
+        Assert.That(result, Is.EquivalentTo([chats.First()]));
+    }
+    
+    [Test]
+    public async Task GetUserGroups_ButGroupDoesNotExist_ShouldReturnEmptyList()
+    {
+        // Arrange 
+        var userId = _fixture.Create<Guid>();
+        
+        _repositoryMock.Setup(r => r.GetByUserIdAsync(userId))
+            .ThrowsAsync(new NotFoundByKeyException<Guid>(userId));
+        
+        // Act 
+        var result = await _service.GetUserGroupsAsync(userId);
+        
+        // Assert 
+        Assert.That(result, Is.Not.Null);
+        Assert.That(result.Count(), Is.EqualTo(0));
+    }
+}