diff --git a/src/src/StevesBot.Webhook/YouTube/LastPostedStreamStore.cs b/src/src/StevesBot.Webhook/YouTube/LastPostedStreamStore.cs
index a82c9a0..4ab8975 100644
--- a/src/src/StevesBot.Webhook/YouTube/LastPostedStreamStore.cs
+++ b/src/src/StevesBot.Webhook/YouTube/LastPostedStreamStore.cs
@@ -6,11 +6,13 @@ internal class LastPostedStreamStore : ILastPostedStreamStore
 
   public void SetValue(string value)
   {
+    ArgumentNullException.ThrowIfNull(value);
     _value = value;
   }
 
   public bool HasValue(string value)
   {
+    ArgumentNullException.ThrowIfNull(value);
     return _value.Equals(value, StringComparison.OrdinalIgnoreCase);
   }
 }
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/DiscordNotificationOptionsTests.cs b/src/tests/StevesBot.Webhook.Tests/Unit/DiscordNotificationOptionsTests.cs
new file mode 100644
index 0000000..8b18ca5
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/DiscordNotificationOptionsTests.cs
@@ -0,0 +1,28 @@
+namespace StevesBot.Webhook.Tests.Unit;
+
+public class DiscordNotificationOptionsTests
+{
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldReturnInstance()
+  {
+    var options = new DiscordNotificationOptions();
+
+    options.ChannelId.Should().BeEmpty();
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithProperties_ItShouldReturnInstance()
+  {
+    var channelId = "1234567890";
+    var messageFormat = "New video uploaded: {VideoTitle}";
+
+    var options = new DiscordNotificationOptions
+    {
+      ChannelId = channelId,
+      MessageFormat = messageFormat
+    };
+
+    options.ChannelId.Should().Be(channelId);
+    options.MessageFormat.Should().Be(messageFormat);
+  }
+}
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/LastPostedStreamStore.cs b/src/tests/StevesBot.Webhook.Tests/Unit/LastPostedStreamStore.cs
new file mode 100644
index 0000000..90f1cd1
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/LastPostedStreamStore.cs
@@ -0,0 +1,36 @@
+namespace StevesBot.Webhook.Tests.Unit;
+
+public class LastPostedStreamStoreTests
+{
+  [Fact]
+  public void SetValue_WhenCalledWithNull_ItShouldThrowArgumentNullException()
+  {
+    var store = new LastPostedStreamStore();
+
+    var act = () => store.SetValue(null!);
+
+    act.Should().Throw<ArgumentNullException>();
+  }
+
+  [Fact]
+  public void HasValue_WhenCalledWithNull_ItShouldThrowArgumentNullException()
+  {
+    var store = new LastPostedStreamStore();
+
+    var act = () => store.HasValue(null!);
+
+    act.Should().Throw<ArgumentNullException>();
+  }
+
+
+  [Fact]
+  public void SetValueHasValue_WhenCalled_ItShouldStoreValue()
+  {
+    var store = new LastPostedStreamStore();
+    var streamId = "test-stream-id";
+
+    store.SetValue(streamId);
+
+    store.HasValue(streamId).Should().BeTrue();
+  }
+}
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/PubSubClientOptionsTests.cs b/src/tests/StevesBot.Webhook.Tests/Unit/PubSubClientOptionsTests.cs
new file mode 100644
index 0000000..324b5f3
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/PubSubClientOptionsTests.cs
@@ -0,0 +1,25 @@
+namespace StevesBot.Webhook.Tests.Unit;
+
+public class PubSubClientOptionsTests
+{
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldReturnInstance()
+  {
+    var options = new PubSubClientOptions();
+
+    options.BaseUrl.Should().BeEmpty();
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithProperties_ItShouldReturnInstance()
+  {
+    var baseUrl = "https://example.com";
+
+    var options = new PubSubClientOptions()
+    {
+      BaseUrl = baseUrl
+    };
+
+    options.BaseUrl.Should().Be(baseUrl);
+  }
+}
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/SubscribeTaskTests.cs b/src/tests/StevesBot.Webhook.Tests/Unit/SubscribeTaskTests.cs
new file mode 100644
index 0000000..463a642
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/SubscribeTaskTests.cs
@@ -0,0 +1,33 @@
+namespace StevesBot.Webhook.Tests.Unit;
+
+public class SubscribeTaskTests
+{
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldReturnInstance()
+  {
+    var task = new SubscribeTask();
+
+    task.CallbackUrl.Should().BeEmpty();
+    task.TopicUrl.Should().BeEmpty();
+    task.ExpiresAt.Should().Be(DateTime.MinValue);
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithProperties_ItShouldReturnInstance()
+  {
+    var callbackUrl = "https://example.com/callback";
+    var topicUrl = "https://example.com/topic";
+    var expiresAt = DateTime.UtcNow.AddDays(1);
+
+    var task = new SubscribeTask
+    {
+      CallbackUrl = callbackUrl,
+      TopicUrl = topicUrl,
+      ExpiresAt = expiresAt
+    };
+
+    task.CallbackUrl.Should().Be(callbackUrl);
+    task.TopicUrl.Should().Be(topicUrl);
+    task.ExpiresAt.Should().Be(expiresAt);
+  }
+}
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/SubscriptionOptionsTests.cs b/src/tests/StevesBot.Webhook.Tests/Unit/SubscriptionOptionsTests.cs
new file mode 100644
index 0000000..f86d1e0
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/SubscriptionOptionsTests.cs
@@ -0,0 +1,29 @@
+namespace StevesBot.Webhook.Tests.Unit;
+
+public class SubscriptionOptionsTests
+{
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldReturnInstance()
+  {
+    var options = new SubscriptionOptions();
+
+    options.CallbackUrl.Should().BeEmpty();
+    options.TopicUrl.Should().BeEmpty();
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithProperties_ItShouldReturnInstance()
+  {
+    var callbackUrl = "https://example.com/callback";
+    var topicUrl = "https://example.com/topic";
+
+    var options = new SubscriptionOptions
+    {
+      CallbackUrl = callbackUrl,
+      TopicUrl = topicUrl
+    };
+
+    options.CallbackUrl.Should().Be(callbackUrl);
+    options.TopicUrl.Should().Be(topicUrl);
+  }
+}
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Unit/YouTubeClientOptionsTests.cs b/src/tests/StevesBot.Webhook.Tests/Unit/YouTubeClientOptionsTests.cs
new file mode 100644
index 0000000..2746534
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Unit/YouTubeClientOptionsTests.cs
@@ -0,0 +1,29 @@
+namespace StevesBot.Webhook.Tests.Unit;
+
+public class YouTubeClientOptionsTests
+{
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldReturnInstance()
+  {
+    var options = new YouTubeClientOptions();
+
+    options.BaseUrl.Should().BeEmpty();
+    options.ApiKey.Should().BeEmpty();
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithProperties_ItShouldReturnInstance()
+  {
+    var baseUrl = "https://example.com";
+    var apiKey = "test-api-key";
+
+    var options = new YouTubeClientOptions
+    {
+      BaseUrl = baseUrl,
+      ApiKey = apiKey
+    };
+
+    options.BaseUrl.Should().Be(baseUrl);
+    options.ApiKey.Should().Be(apiKey);
+  }
+}
\ No newline at end of file
diff --git a/src/tests/StevesBot.Webhook.Tests/Usings.cs b/src/tests/StevesBot.Webhook.Tests/Usings.cs
new file mode 100644
index 0000000..4617e08
--- /dev/null
+++ b/src/tests/StevesBot.Webhook.Tests/Usings.cs
@@ -0,0 +1,2 @@
+global using StevesBot.Webhook.YouTube;
+global using StevesBot.Webhook.YouTube.Tasks;
\ No newline at end of file