diff --git a/src/src/StevesBot.Webhook/YouTube/Handlers/VerifySubscriptionHandler.cs b/src/src/StevesBot.Webhook/YouTube/Handlers/VerifySubscriptionHandler.cs
index 506dac2..be548f6 100644
--- a/src/src/StevesBot.Webhook/YouTube/Handlers/VerifySubscriptionHandler.cs
+++ b/src/src/StevesBot.Webhook/YouTube/Handlers/VerifySubscriptionHandler.cs
@@ -10,7 +10,8 @@ internal static class VerifySubscriptionHandler
     [FromQuery(Name = "hub.lease_seconds")] string? leaseSeconds,
     [FromServices] IOptions<SubscriptionOptions> subOptions,
     [FromServices] ILogger<Program> logger,
-    [FromServices] ConcurrentQueue<SubscribeTask> subscriptionQueue
+    [FromServices] ConcurrentQueue<SubscribeTask> subscriptionQueue,
+    [FromServices] TimeProvider timeProvider
   )
   {
     if (mode is "denied")
@@ -44,7 +45,7 @@ internal static class VerifySubscriptionHandler
       {
         CallbackUrl = subOptions.Value.CallbackUrl,
         TopicUrl = topic,
-        ExpiresAt = DateTime.UtcNow.AddSeconds(parsedSeconds),
+        ExpiresAt = timeProvider.GetUtcNow().AddSeconds(parsedSeconds),
       };
 
       subscriptionQueue.Enqueue(task);
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/VerifySubscriptionHandlerTests.cs b/src/tests/StevesBot.Webhook.Tests/Unit/VerifySubscriptionHandlerTests.cs
index 75cb231..4c3f278 100644
--- a/src/tests/StevesBot.Webhook.Tests/Unit/VerifySubscriptionHandlerTests.cs
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/VerifySubscriptionHandlerTests.cs
@@ -1,3 +1,5 @@
+using System.Globalization;
+
 namespace StevesBot.Webhook.Tests.Unit;
 
 public class VerifySubscriptionHandlerTests
@@ -5,6 +7,7 @@ public class VerifySubscriptionHandlerTests
   private readonly Mock<IOptions<SubscriptionOptions>> _mockSubOptions = new();
   private readonly Mock<ILogger<Program>> _mockLogger = new();
   private readonly ConcurrentQueue<SubscribeTask> _subscriptionQueue = new();
+  private readonly Mock<TimeProvider> _mockTimeProvider = new();
 
   [Fact]
   public void Handle_WhenModeIsDenied_ItShouldReturnBadRequest()
@@ -14,6 +17,95 @@ public class VerifySubscriptionHandlerTests
     result.Should().BeOfType<BadRequest<string>>();
   }
 
+  [Fact]
+  public void Handle_WhenTopicDoesNotMatch_ItShouldReturnNotFound()
+  {
+    SetupSubscriptionOptions(new() { TopicUrl = "expected-topic" });
+
+    var result = Handle("subscribe", "wrong-topic");
+
+    result.Should().BeOfType<NotFound>();
+  }
+
+  [Fact]
+  public void Handle_WhenModeIsSubscribeAndLeaseSecondsIsNotPresent_ItShouldReturnBadRequest()
+  {
+    var topic = "topic";
+
+    SetupSubscriptionOptions(new() { TopicUrl = topic });
+
+    var result = Handle("subscribe", topic, leaseSeconds: null);
+
+    result.Should().BeOfType<BadRequest<string>>();
+  }
+
+  [Fact]
+  public void Handle_WhenModeIsSubscribeAndLeaseSecondsIsInvalid_ItShouldReturnBadRequest()
+  {
+    var topic = "topic";
+
+    SetupSubscriptionOptions(new() { TopicUrl = topic });
+
+    var result = Handle("subscribe", topic, leaseSeconds: "invalid");
+
+    result.Should().BeOfType<BadRequest<string>>();
+  }
+
+  [Fact]
+  public void Handle_WhenModeIsUnsubscribe_ItShouldReturnOk()
+  {
+    var topic = "topic";
+
+    SetupSubscriptionOptions(new() { TopicUrl = topic });
+
+    var result = Handle("unsubscribe", topic, challenge: "challenge");
+
+    result.Should().BeOfType<ContentHttpResult>();
+  }
+
+  [Fact]
+  public void Handle_WhenModeIsSubscribe_ItShouldEnqueueSubscriptionTask()
+  {
+    var challenge = "challenge";
+    var topic = "topic";
+    var leaseSeconds = 3600;
+    var callbackUrl = "https://example.com/callback";
+    var now = DateTime.UtcNow;
+
+    _mockTimeProvider
+      .Setup(static tp => tp.GetUtcNow())
+      .Returns(now);
+
+    SetupSubscriptionOptions(new() { TopicUrl = topic, CallbackUrl = callbackUrl });
+
+    var result = Handle(
+      "subscribe",
+      topic,
+      challenge: challenge,
+      leaseSeconds: leaseSeconds.ToString(CultureInfo.InvariantCulture)
+    );
+
+    result.Should().BeOfType<ContentHttpResult>();
+    result.As<ContentHttpResult>().ResponseContent.Should().Be(challenge);
+
+    _subscriptionQueue.Count.Should().Be(1);
+
+    var task = _subscriptionQueue.TryDequeue(out var dequeuedTask);
+
+    task.Should().BeTrue();
+    dequeuedTask.Should().NotBeNull();
+    dequeuedTask!.CallbackUrl.Should().Be(callbackUrl);
+    dequeuedTask.TopicUrl.Should().Be(topic);
+    dequeuedTask.ExpiresAt.Should().Be(now.AddSeconds(leaseSeconds));
+  }
+
+  private void SetupSubscriptionOptions(SubscriptionOptions options)
+  {
+    _mockSubOptions
+      .Setup(static o => o.Value)
+      .Returns(options);
+  }
+
   private IResult Handle(string mode, string topic, string? reason = null, string? challenge = null, string? leaseSeconds = null)
   {
     return VerifySubscriptionHandler.Handle(
@@ -24,7 +116,8 @@ public class VerifySubscriptionHandlerTests
       leaseSeconds,
       _mockSubOptions.Object,
       _mockLogger.Object,
-      _subscriptionQueue
+      _subscriptionQueue,
+      _mockTimeProvider.Object
     );
   }
 }
\ No newline at end of file