Add unit tests for InvitationGenerator and JwtService

Introduces unit tests for the InvitationGenerator and JwtService classes. The tests cover invitation code generation, repository interaction, code uniqueness, and JWT token generation and validation.

Govor.API.Tests/UnitTests/Services/Authentication/JwtServiceTests.cs

@@ -0,0 +1,59 @@
+using System.IdentityModel.Tokens.Jwt;
+using AutoFixture;
+using Govor.API.Services.Authentication;
+using Govor.API.Services.Authentication.Interfaces;
+using Govor.Core.Models;
+using Microsoft.Extensions.Options;
+using Moq;
+
+namespace Govor.API.Tests.UnitTests.Services.Authentication;
+
+[TestFixture]
+public class JwtServiceTests
+{
+    private Fixture _fixture;
+    private Mock<IOptions<JwtOption>> _jwtOptionsMock;
+    private Mock<IInvitesService> _invitesServiceMock;
+    private IJwtService _jwtService;
+
+    private JwtOption _testJwtOptions;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _fixture = new Fixture();
+        _fixture.Behaviors.OfType<ThrowingRecursionBehavior>().ToList().ForEach(b => _fixture.Behaviors.Remove(b));
+        _fixture.Behaviors.Add(new OmitOnRecursionBehavior());
+
+        _testJwtOptions = new JwtOption
+        {
+            SecretKeу = "THIS IS A TEST SECRET KEY THAT IS LONG ENOUGH", // Ensure key size is sufficient for HMACSHA256
+            Hours = 1
+        };
+
+        _jwtOptionsMock = new Mock<IOptions<JwtOption>>();
+        _jwtOptionsMock.Setup(o => o.Value).Returns(_testJwtOptions);
+
+        _invitesServiceMock = new Mock<IInvitesService>();
+        
+        _jwtService = new JwtService(_jwtOptionsMock.Object, _invitesServiceMock.Object);
+    }
+
+    [Test]
+    public void GenerateJwtToken_ShouldReturnValidJwtString()
+    {
+        // Arrange
+        var user = _fixture.Create<User>();
+        var expectedRole = "User";
+        _invitesServiceMock.Setup(s => s.GetRole(user)).Returns(Task.FromResult(expectedRole));
+        // Act 
+        var tokenString = _jwtService.GenerateJwtToken(user);
+
+        // Assert
+        Assert.That(tokenString, Is.Not.Null.And.Not.Empty);
+        
+        // Attempt to parse the token to ensure it's a JWT
+        var handler = new JwtSecurityTokenHandler();
+        Assert.DoesNotThrow(() => handler.ReadJwtToken(tokenString));
+    }
+}