Add unit tests for various services and functionalities

- Implement tests for ChatLine utility methods including color tag detection and stripping.
- Create comprehensive tests for CommandHandler to validate command handling and status updates.
- Add tests for DataMigrationService to ensure correct ANSI to color tag conversion.
- Enhance FileValidationHelperTests with audio file validation tests.
- Introduce ImageToAsciiServiceTests to verify image dimension retrieval.
- Develop IrcMessageFormatterTests for message formatting and color tag conversion.
- Add JwtTokenServiceTests to validate JWT token generation and hashing.
- Implement LinkEmbedServiceTests for URL extraction and Open Graph tag parsing.
- Update EchoHub.Tests.csproj to include necessary project references.

src/EchoHub.Tests/JwtTokenServiceTests.cs

@@ -0,0 +1,195 @@
+using System.IdentityModel.Tokens.Jwt;
+using EchoHub.Core.Models;
+using EchoHub.Server.Auth;
+using Microsoft.Extensions.Configuration;
+using Xunit;
+
+namespace EchoHub.Tests;
+
+public class JwtTokenServiceTests
+{
+    private const string TestSecret = "this_is_a_test_secret_key_that_is_long_enough_for_hmac_sha256";
+    private const string TestIssuer = "TestIssuer";
+    private const string TestAudience = "TestAudience";
+
+    private static JwtTokenService CreateService(
+        string? secret = null, string? issuer = null, string? audience = null)
+    {
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Jwt:Secret"] = secret ?? TestSecret,
+                ["Jwt:Issuer"] = issuer ?? TestIssuer,
+                ["Jwt:Audience"] = audience ?? TestAudience,
+            })
+            .Build();
+
+        return new JwtTokenService(config);
+    }
+
+    private static User CreateUser(
+        string username = "alice",
+        ServerRole role = ServerRole.Member,
+        string? displayName = null) => new()
+    {
+        Id = Guid.NewGuid(),
+        Username = username,
+        PasswordHash = "hash",
+        DisplayName = displayName,
+        Role = role,
+    };
+
+    // ── Constructor ───────────────────────────────────────────────────
+
+    [Fact]
+    public void Constructor_MissingSecret_Throws()
+    {
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Jwt:Issuer"] = TestIssuer,
+                ["Jwt:Audience"] = TestAudience,
+            })
+            .Build();
+
+        Assert.Throws<InvalidOperationException>(() => new JwtTokenService(config));
+    }
+
+    [Fact]
+    public void Constructor_MissingIssuer_Throws()
+    {
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Jwt:Secret"] = TestSecret,
+                ["Jwt:Audience"] = TestAudience,
+            })
+            .Build();
+
+        Assert.Throws<InvalidOperationException>(() => new JwtTokenService(config));
+    }
+
+    [Fact]
+    public void Constructor_MissingAudience_Throws()
+    {
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Jwt:Secret"] = TestSecret,
+                ["Jwt:Issuer"] = TestIssuer,
+            })
+            .Build();
+
+        Assert.Throws<InvalidOperationException>(() => new JwtTokenService(config));
+    }
+
+    // ── GenerateAccessToken ───────────────────────────────────────────
+
+    [Fact]
+    public void GenerateAccessToken_ContainsExpectedClaims()
+    {
+        var service = CreateService();
+        var user = CreateUser(username: "bob", role: ServerRole.Admin, displayName: "Bob Smith");
+
+        var (token, _) = service.GenerateAccessToken(user);
+        var handler = new JwtSecurityTokenHandler();
+        var jwt = handler.ReadJwtToken(token);
+
+        Assert.Equal(user.Id.ToString(), jwt.Claims.First(c => c.Type == "sub").Value);
+        Assert.Equal("bob", jwt.Claims.First(c => c.Type == "username").Value);
+        Assert.Equal("Bob Smith", jwt.Claims.First(c => c.Type == "display_name").Value);
+        Assert.Equal("Admin", jwt.Claims.First(c => c.Type == "role").Value);
+        Assert.NotNull(jwt.Claims.FirstOrDefault(c => c.Type == "jti"));
+    }
+
+    [Fact]
+    public void GenerateAccessToken_ExpiresIn15Minutes()
+    {
+        var service = CreateService();
+        var user = CreateUser();
+
+        var (_, expiresAt) = service.GenerateAccessToken(user);
+        var diff = expiresAt - DateTimeOffset.UtcNow;
+
+        // Should be approximately 15 minutes (allow 30s tolerance)
+        Assert.InRange(diff.TotalMinutes, 14.5, 15.5);
+    }
+
+    [Fact]
+    public void GenerateAccessToken_DifferentTokensForSameUser()
+    {
+        var service = CreateService();
+        var user = CreateUser();
+
+        var (token1, _) = service.GenerateAccessToken(user);
+        var (token2, _) = service.GenerateAccessToken(user);
+
+        Assert.NotEqual(token1, token2);
+    }
+
+    [Fact]
+    public void GenerateAccessToken_DisplayNameFallsBackToUsername()
+    {
+        var service = CreateService();
+        var user = CreateUser(username: "alice"); // DisplayName is null
+
+        var (token, _) = service.GenerateAccessToken(user);
+        var handler = new JwtSecurityTokenHandler();
+        var jwt = handler.ReadJwtToken(token);
+
+        Assert.Equal("alice", jwt.Claims.First(c => c.Type == "display_name").Value);
+    }
+
+    // ── GenerateRefreshToken ──────────────────────────────────────────
+
+    [Fact]
+    public void GenerateRefreshToken_Returns88CharBase64()
+    {
+        var token = JwtTokenService.GenerateRefreshToken();
+
+        // 64 bytes → 88 base64 characters
+        Assert.Equal(88, token.Length);
+        // Should be valid base64
+        var bytes = Convert.FromBase64String(token);
+        Assert.Equal(64, bytes.Length);
+    }
+
+    [Fact]
+    public void GenerateRefreshToken_UniqueBetweenCalls()
+    {
+        var token1 = JwtTokenService.GenerateRefreshToken();
+        var token2 = JwtTokenService.GenerateRefreshToken();
+
+        Assert.NotEqual(token1, token2);
+    }
+
+    // ── HashToken ─────────────────────────────────────────────────────
+
+    [Fact]
+    public void HashToken_DeterministicForSameInput()
+    {
+        var hash1 = JwtTokenService.HashToken("test-token");
+        var hash2 = JwtTokenService.HashToken("test-token");
+
+        Assert.Equal(hash1, hash2);
+    }
+
+    [Fact]
+    public void HashToken_DifferentForDifferentInput()
+    {
+        var hash1 = JwtTokenService.HashToken("token-a");
+        var hash2 = JwtTokenService.HashToken("token-b");
+
+        Assert.NotEqual(hash1, hash2);
+    }
+
+    [Fact]
+    public void HashToken_ReturnsBase64String()
+    {
+        var hash = JwtTokenService.HashToken("test-token");
+
+        // SHA256 → 32 bytes → 44 base64 characters
+        var bytes = Convert.FromBase64String(hash);
+        Assert.Equal(32, bytes.Length);
+    }
+}