Add more tests

tests/Jellyfin.Server.Integration.Tests/Controllers/SessionControllerTests.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Net;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Jellyfin.Server.Integration.Tests.Controllers;
+
+public class SessionControllerTests : IClassFixture<JellyfinApplicationFactory>
+{
+    private readonly JellyfinApplicationFactory _factory;
+    private static string? _accessToken;
+
+    public SessionControllerTests(JellyfinApplicationFactory factory)
+    {
+        _factory = factory;
+    }
+
+    [Fact]
+    public async Task GetSessions_NonExistentUserId_NotFound()
+    {
+        var client = _factory.CreateClient();
+        client.DefaultRequestHeaders.AddAuthHeader(_accessToken ??= await AuthHelper.CompleteStartupAsync(client).ConfigureAwait(false));
+
+        using var response = await client.GetAsync($"Session/Sessions?userId={Guid.NewGuid()}").ConfigureAwait(false);
+        Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
+    }
+}