feat: add support for file source and url source

src/AnthropicClient/Json/SourceConverter.cs

@@ -16,6 +16,8 @@ class SourceConverter : JsonConverter<Source>
     {
       SourceType.Text => JsonSerializer.Deserialize<TextSource>(root.GetRawText(), options)!,
       SourceType.Content => JsonSerializer.Deserialize<CustomSource>(root.GetRawText(), options)!,
+      SourceType.File => JsonSerializer.Deserialize<FileSource>(root.GetRawText(), options)!,
+      SourceType.Url => JsonSerializer.Deserialize<UrlSource>(root.GetRawText(), options)!,
       SourceType.Base64 => DeserializeBase64Source(root, options),
       _ => throw new JsonException($"Unknown source type: {type}")
     };
@@ -54,6 +56,18 @@ class SourceConverter : JsonConverter<Source>
       return;
     }
 
+    if (value is FileSource fileSource)
+    {
+      JsonSerializer.Serialize(writer, fileSource, options);
+      return;
+    }
+
+    if (value is UrlSource urlSource)
+    {
+      JsonSerializer.Serialize(writer, urlSource, options);
+      return;
+    }
+
     JsonSerializer.Serialize(writer, value, value.GetType(), options);
   }
 }

src/AnthropicClient/Models/FileSource.cs

@@ -0,0 +1,33 @@
+using System.Text.Json.Serialization;
+
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a file source in the Anthropic API.
+/// </summary>
+public class FileSource : Source
+{
+  /// <summary>
+  /// Gets or sets the unique identifier for the file source.
+  /// </summary>
+  [JsonPropertyName("file_id")]
+  public string Id { get; init; } = string.Empty;
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="FileSource"/> class.
+  /// </summary>
+  /// <returns>A new instance of <see cref="FileSource"/> with the type set to "file".</returns>
+  public FileSource() : base(SourceType.File)
+  {
+  }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="FileSource"/> class with a specified file ID.
+  /// </summary>
+  /// <param name="id">The unique identifier for the file source.</param>
+  /// <returns>A new instance of <see cref="FileSource"/>.</returns>
+  public FileSource(string id) : base(SourceType.File)
+  {
+    Id = id;
+  }
+}

src/AnthropicClient/Models/ImageContent.cs

@@ -53,4 +53,32 @@ public class ImageContent : Content
 
     Source = new ImageSource(mediaType, data);
   }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="ImageContent"/> class.
+  /// </summary>
+  /// <param name="source">The source of the image.</param>
+  /// <returns>A new instance of the <see cref="ImageContent"/> class.</returns>
+  /// <exception cref="ArgumentNullException">Thrown when the source is null.</exception>
+  public ImageContent(Source source) : base(ContentType.Image)
+  {
+    ArgumentValidator.ThrowIfNull(source, nameof(source));
+
+    Source = source;
+  }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="ImageContent"/> class.
+  /// </summary>
+  /// <param name="source">The source of the image.</param>
+  /// <param name="cacheControl">The cache control to be used for the content.</param>
+  /// <returns>A new instance of the <see cref="ImageContent"/> class.</returns>
+  /// <exception cref="ArgumentNullException">Thrown when the source or cache control is null.</exception>
+  public ImageContent(Source source, CacheControl cacheControl) : base(ContentType.Image, cacheControl)
+  {
+    ArgumentValidator.ThrowIfNull(source, nameof(source));
+    ArgumentValidator.ThrowIfNull(cacheControl, nameof(cacheControl));
+
+    Source = source;
+  }
 }

src/AnthropicClient/Models/SourceType.cs

@@ -19,4 +19,14 @@ public static class SourceType
   /// The text document source type.
   /// </summary>
   public const string Text = "text";
+
+  /// <summary>
+  /// The file document source type.
+  /// </summary>
+  public const string File = "file";
+
+  /// <summary>
+  /// The URL document source type.
+  /// </summary>
+  public const string Url = "url";
 }

src/AnthropicClient/Models/UrlSource.cs

@@ -0,0 +1,30 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a URL source in the Anthropic API.
+/// </summary>
+public class UrlSource : Source
+{
+  /// <summary>
+  /// Gets or sets the URL of the source document.
+  /// </summary>
+  public string Url { get; init; } = string.Empty;
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="UrlSource"/> class.
+  /// </summary>
+  /// <returns>A new instance of <see cref="UrlSource"/> with the type set to "url".</returns>
+  public UrlSource() : base(SourceType.Url)
+  {
+  }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="UrlSource"/> class with a specified URL.
+  /// </summary>
+  /// <param name="url">The URL of the source document.</param>
+  /// <returns>A new instance of <see cref="UrlSource"/>.</returns>
+  public UrlSource(string url) : base(SourceType.Url)
+  {
+    Url = url;
+  }
+}

tests/AnthropicClient.Tests/EndToEnd/AnthropicApiClientTests.cs

@@ -2,8 +2,15 @@ using AnthropicClient.Tests.Files;
 
 namespace AnthropicClient.Tests.EndToEnd;
 
-public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndToEndTest(configFixture)
+public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndToEndTest(configFixture), IAsyncLifetime
 {
+  private readonly List<string> _filesToDelete = [];
+
+  public Task InitializeAsync()
+  {
+    return Task.CompletedTask;
+  }
+
   [Fact]
   public async Task CreateMessageAsync_WhenCalled_ItShouldReturnResponse()
   {
@@ -96,11 +103,41 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     text.Should().Contain("elephant");
   }
 
+  [Fact]
+  public async Task CreateMessageAsync_WhenImageIsSentAsUrl_ItShouldReturnResponse()
+  {
+    var request = new MessageRequest(
+      model: AnthropicModels.Claude3Haiku,
+      messages: [
+        new(MessageRole.User, [
+          new ImageContent(new UrlSource("https://ftp.stevanfreeborn.com/share/anthropic-client/ant.jpg")),
+          new TextContent("What is in this image?")
+        ]),
+      ]
+    );
+
+    var result = await _client.CreateMessageAsync(request);
+
+    result.IsSuccess.Should().BeTrue();
+    result.Value.Should().BeOfType<MessageResponse>();
+    result.Value.Content.Should().NotBeNullOrEmpty();
+
+    var text = result.Value.Content.Aggregate("", static (acc, content) =>
+    {
+      if (content is TextContent textContent)
+      {
+        acc += textContent.Text;
+      }
+
+      return acc;
+    });
+
+    text.Should().Contain("ant");
+  }
+
   [Fact]
   public async Task CreateMessageAsync_WhenSystemMessagesContainCacheControl_ItShouldUseCache()
   {
-    var client = CreateClient(new HttpClient());
-
     var storyPath = TestFileHelper.GetTestFilePath("story.txt");
     var storyText = await File.ReadAllTextAsync(storyPath);
 
@@ -127,7 +164,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     request.Messages.Add(new(MessageRole.Assistant, resultOne.Value.Content));
     request.Messages.Add(new(MessageRole.User, [new TextContent("What is the main theme of this story?")]));
 
-    var resultTwo = await client.CreateMessageAsync(request);
+    var resultTwo = await _client.CreateMessageAsync(request);
 
     resultTwo.IsSuccess.Should().BeTrue();
     resultTwo.Value.Should().BeOfType<MessageResponse>();
@@ -138,8 +175,6 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
   [Fact]
   public async Task CreateMessageAsync_WhenMessagesContainCacheControl_ItShouldUseCache()
   {
-    var client = CreateClient(new HttpClient());
-
     var storyPath = TestFileHelper.GetTestFilePath("story.txt");
     var storyText = await File.ReadAllTextAsync(storyPath);
 
@@ -153,7 +188,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
       ]
     );
 
-    var resultOne = await client.CreateMessageAsync(request);
+    var resultOne = await _client.CreateMessageAsync(request);
 
     resultOne.IsSuccess.Should().BeTrue();
     resultOne.Value.Should().BeOfType<MessageResponse>();
@@ -163,7 +198,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     request.Messages.Add(new(MessageRole.Assistant, resultOne.Value.Content));
     request.Messages.Add(new(MessageRole.User, [new TextContent("What is the main theme of this story?")]));
 
-    var resultTwo = await client.CreateMessageAsync(request);
+    var resultTwo = await _client.CreateMessageAsync(request);
 
     resultTwo.IsSuccess.Should().BeTrue();
     resultTwo.Value.Should().BeOfType<MessageResponse>();
@@ -174,8 +209,6 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
   [Fact]
   public async Task CreateMessageAsync_WhenToolsContainCacheControl_ItShouldUseCache()
   {
-    var client = CreateClient(new HttpClient());
-
     var func = (string ticker) => ticker;
 
     var tools = Enumerable
@@ -195,7 +228,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
       tools: tools
     );
 
-    var resultOne = await client.CreateMessageAsync(request);
+    var resultOne = await _client.CreateMessageAsync(request);
 
     resultOne.IsSuccess.Should().BeTrue();
     resultOne.Value.Should().BeOfType<MessageResponse>();
@@ -205,7 +238,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     request.Messages.Add(new(MessageRole.Assistant, resultOne.Value.Content));
     request.Messages.Add(new(MessageRole.User, [new TextContent("Could you tell me the stock price for AAPL?")]));
 
-    var resultTwo = await client.CreateMessageAsync(request);
+    var resultTwo = await _client.CreateMessageAsync(request);
 
     resultTwo.IsSuccess.Should().BeTrue();
     resultTwo.Value.Should().BeOfType<MessageResponse>();
@@ -228,9 +261,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
       ]
     );
 
-    var client = CreateClient(new HttpClient());
-
-    var result = await client.CreateMessageAsync(request);
+    var result = await _client.CreateMessageAsync(request);
 
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().BeOfType<MessageResponse>();
@@ -256,8 +287,6 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     var bytes = await File.ReadAllBytesAsync(pdfPath);
     var base64Data = Convert.ToBase64String(bytes);
 
-    var client = CreateClient(new HttpClient());
-
     var request = new MessageRequest(
       model: AnthropicModels.Claude35Sonnet,
       messages: [
@@ -268,7 +297,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
       ]
     );
 
-    var resultOne = await client.CreateMessageAsync(request);
+    var resultOne = await _client.CreateMessageAsync(request);
 
     resultOne.IsSuccess.Should().BeTrue();
     resultOne.Value.Should().BeOfType<MessageResponse>();
@@ -278,7 +307,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     request.Messages.Add(new(MessageRole.Assistant, resultOne.Value.Content));
     request.Messages.Add(new(MessageRole.User, [new TextContent("What is the main theme of this paper?")]));
 
-    var resultTwo = await client.CreateMessageAsync(request);
+    var resultTwo = await _client.CreateMessageAsync(request);
 
     resultTwo.IsSuccess.Should().BeTrue();
     resultTwo.Value.Should().BeOfType<MessageResponse>();
@@ -395,6 +424,58 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     citations.OfType<ContentBlockLocationCitation>().Should().NotBeEmpty();
   }
 
+  [Fact]
+  public async Task CreateMessageAsync_WhenCitationsAreEnabledForFileSource_ItShouldReturnCitationsInResponse()
+  {
+    var fileName = "story.txt";
+    var fileType = "text/plain";
+    var filePath = TestFileHelper.GetTestFilePath("story.txt");
+    var fileContent = await File.ReadAllBytesAsync(filePath);
+    var createFileRequest = new CreateFileRequest(fileContent, fileName, fileType);
+
+    var httpClient = new HttpClient();
+    httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
+    var client = CreateClient(httpClient);
+
+    var createdFile = await client.CreateFileAsync(createFileRequest);
+
+    var request = new MessageRequest(
+      model: AnthropicModels.Claude35HaikuLatest,
+      messages: [
+        new(
+          MessageRole.User,
+          [
+            new DocumentContent(new FileSource(createdFile.Value.Id))
+            {
+              Title = "A Story",
+              Context = "This is a trustworthy document.",
+              Citations = new() { Enabled = true }
+            },
+            new TextContent("Can you tell me what the title of this story is?"),
+          ]
+        )
+      ]
+    );
+
+    var result = await client.CreateMessageAsync(request);
+
+    result.IsSuccess.Should().BeTrue();
+
+    var textContents = result.Value.Content.OfType<TextContent>();
+
+    var messageContent = textContents.Aggregate(new StringBuilder(), (sb, content) =>
+    {
+      sb.Append(content.Text);
+      return sb;
+    });
+    messageContent.ToString().Should().MatchRegex("The Forgotten Lighthouse");
+
+    var citations = textContents.SelectMany(static c => c.Citations is null ? [] : c.Citations);
+    citations.OfType<CharacterLocationCitation>().Should().NotBeEmpty();
+
+    _filesToDelete.Add(createdFile.Value.Id);
+  }
+
   [Fact]
   public async Task CreateMessageAsync_WhenStreamingAndCitationsAreEnabledForTextDocumentSource_ItShouldReturnCitationsInResponse()
   {
@@ -516,6 +597,64 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     citations.OfType<ContentBlockLocationCitation>().Should().NotBeEmpty();
   }
 
+  [Fact]
+  public async Task CreateMessageAsync_WhenStreamingAndCitationsAreEnabledForFileSource_ItShouldReturnCitationsInResponse()
+  {
+    var fileName = "story.txt";
+    var fileType = "text/plain";
+    var filePath = TestFileHelper.GetTestFilePath("story.txt");
+    var fileContent = await File.ReadAllBytesAsync(filePath);
+    var createFileRequest = new CreateFileRequest(fileContent, fileName, fileType);
+
+    using var httpClient = new HttpClient();
+    httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
+    var client = CreateClient(httpClient);
+
+    var createdFile = await client.CreateFileAsync(createFileRequest);
+
+    var request = new StreamMessageRequest(
+      model: AnthropicModels.Claude35HaikuLatest,
+      messages: [
+        new(
+          MessageRole.User,
+          [
+            new DocumentContent(new FileSource(createdFile.Value.Id))
+            {
+              Title = "A Story",
+              Context = "This is a trustworthy document.",
+              Citations = new() { Enabled = true }
+            },
+            new TextContent("Can you tell me what the title of this story is?"),
+          ]
+        )
+      ]
+    );
+
+    var result = client.CreateMessageAsync(request);
+
+    var messageCompleteEvent = await result
+      .Where(e => e.Type is EventType.MessageComplete)
+      .FirstAsync();
+
+    var textContents = messageCompleteEvent.Data
+      .As<MessageCompleteEventData>()
+      .Message
+      .Content
+      .OfType<TextContent>();
+
+    var messageContent = textContents.Aggregate(new StringBuilder(), (sb, content) =>
+    {
+      sb.Append(content.Text);
+      return sb;
+    });
+    messageContent.ToString().Should().MatchRegex("The Forgotten Lighthouse");
+
+    var citations = textContents.SelectMany(static c => c.Citations is null ? [] : c.Citations);
+    citations.OfType<CharacterLocationCitation>().Should().NotBeEmpty();
+
+    _filesToDelete.Add(createdFile.Value.Id);
+  }
+
   [Fact]
   public async Task CountMessageTokensAsync_WhenCalled_ItShouldReturnResponse()
   {
@@ -697,7 +836,7 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     var fileContent = await File.ReadAllBytesAsync(filePath);
     var request = new CreateFileRequest(fileContent, fileName, fileType);
 
-    var httpClient = new HttpClient();
+    using var httpClient = new HttpClient();
     httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
     var client = CreateClient(httpClient);
 
@@ -707,12 +846,14 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     result.Value.Should().BeOfType<AnthropicFile>();
     result.Value.Name.Should().Be(fileName);
     result.Value.MimeType.Should().Be(fileType);
+
+    _filesToDelete.Add(result.Value.Id);
   }
 
   [Fact]
   public async Task ListFilesAsync_WhenCalled_ItShouldReturnPageOfFiles()
   {
-    var httpClient = new HttpClient();
+    using var httpClient = new HttpClient();
     httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
     var client = CreateClient(httpClient);
 
@@ -725,12 +866,14 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().BeOfType<Page<AnthropicFile>>();
     result.Value.Data.Should().ContainSingle(f => f.Id == createdFile.Value.Id);
+
+    _filesToDelete.Add(createdFile.Value.Id);
   }
 
   [Fact]
   public async Task ListAllFilesAsync_WhenCalled_ItShouldReturnAllFiles()
   {
-    var httpClient = new HttpClient();
+    using var httpClient = new HttpClient();
     httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
     var client = CreateClient(httpClient);
 
@@ -741,14 +884,18 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     var responses = await client.ListAllFilesAsync(limit: 1).ToListAsync();
 
     responses.Should().HaveCountGreaterThan(0);
-    responses.Select(r => r.Value).SelectMany(p => p.Data)
-      .Should().ContainSingle(f => f.Id == createdFile.Value.Id);
+    responses.Select(r => r.Value)
+      .SelectMany(p => p.Data)
+      .Should()
+      .ContainSingle(f => f.Id == createdFile.Value.Id);
+
+    _filesToDelete.Add(createdFile.Value.Id);
   }
 
   [Fact]
   public async Task GetFileInfoAsync_WhenCalled_ItShouldReturnFile()
   {
-    var httpClient = new HttpClient();
+    using var httpClient = new HttpClient();
     httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
     var client = CreateClient(httpClient);
 
@@ -761,12 +908,14 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     result.IsSuccess.Should().BeTrue();
     result.Value.Should().BeOfType<AnthropicFile>();
     result.Value.Id.Should().Be(createdFile.Value.Id);
+
+    _filesToDelete.Add(createdFile.Value.Id);
   }
 
   [Fact]
   public async Task DeleteFileAsync_WhenCalled_ItShouldReturnDeleteResponse()
   {
-    var httpClient = new HttpClient();
+    using var httpClient = new HttpClient();
     httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
     var client = CreateClient(httpClient);
 
@@ -780,4 +929,17 @@ public class AnthropicApiClientTests(ConfigurationFixture configFixture) : EndTo
     result.Value.Should().BeOfType<AnthropicFileDeleteResponse>();
     result.Value.Id.Should().Be(createdFile.Value.Id);
   }
+
+  public async Task DisposeAsync()
+  {
+    using var httpClient = new HttpClient();
+    httpClient.DefaultRequestHeaders.Add("anthropic-beta", "files-api-2025-04-14");
+    var client = CreateClient(httpClient);
+
+    foreach (var file in _filesToDelete)
+    {
+      var result = await client.DeleteFileAsync(file);
+      result.IsSuccess.Should().BeTrue();
+    }
+  }
 }

tests/AnthropicClient.Tests/Unit/Models/FileSourceTests.cs

@@ -0,0 +1,52 @@
+namespace AnthropicClient.Tests.Unit.Models;
+
+public class FileSourceTests : SerializationTest
+{
+  private readonly string _testJson = @"{
+    ""file_id"": ""id"",
+    ""type"": ""file""
+  }";
+
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldInitializeProperties()
+  {
+    var result = new FileSource();
+
+    result.Type.Should().Be("file");
+    result.Id.Should().BeEmpty();
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithValues_ItShouldInitializeProperties()
+  {
+    var id = "id";
+    var type = "type";
+
+    var result = new FileSource()
+    {
+      Id = id,
+      Type = type,
+    };
+
+    result.Id.Should().Be(id);
+    result.Type.Should().Be(type);
+  }
+
+  [Fact]
+  public void JsonSerialization_WhenSerialized_ItShouldHaveExpectedShape()
+  {
+    var source = new FileSource() { Id = "id" };
+
+    var result = Serialize<Source>(source);
+
+    JsonAssert.Equal(_testJson, result);
+  }
+
+  [Fact]
+  public void JsonDeserialization_WhenDeserialized_ItShouldHaveExpectedValues()
+  {
+    var result = Deserialize<Source>(_testJson);
+
+    result.Should().BeEquivalentTo(new FileSource() { Id = "id" });
+  }
+}

tests/AnthropicClient.Tests/Unit/Models/ImageContentTests.cs

@@ -77,7 +77,7 @@ public class ImageContentTests : SerializationTest
   }
 
   [Fact]
-  public void Constructor_WhenCalledWithCacheControlAndMediatTypeIsNull_ItShouldThrowArgumentNullException()
+  public void Constructor_WhenCalledWithCacheControlAndMediaTypeIsNull_ItShouldThrowArgumentNullException()
   {
     var expectedData = "data";
     var cacheControl = new EphemeralCacheControl();
@@ -98,6 +98,49 @@ public class ImageContentTests : SerializationTest
     action.Should().Throw<ArgumentNullException>();
   }
 
+  [Fact]
+  public void Constructor_WhenCalledWithSource_ItShouldInitializeSource()
+  {
+    var source = new ImageSource("image/png", "data");
+
+    var result = new ImageContent(source);
+
+    result.Source.Should().BeSameAs(source);
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithSourceAndCacheControl_ItShouldInitializeSourceAndCacheControl()
+  {
+    var source = new ImageSource("image/png", "data");
+    var cacheControl = new EphemeralCacheControl();
+
+    var result = new ImageContent(source, cacheControl);
+
+    result.Source.Should().BeSameAs(source);
+    result.CacheControl.Should().BeSameAs(cacheControl);
+  }
+
+  [Fact]
+  public void Constructor_WhenSourceIsNull_ItShouldThrowArgumentNullException()
+  {
+    Source? source = null;
+
+    var action = () => new ImageContent(source!);
+
+    action.Should().Throw<ArgumentNullException>();
+  }
+
+  [Fact]
+  public void Constructor_WhenCacheControlIsNull_ItShouldThrowNullException()
+  {
+    var source = new ImageSource("image/png", "data");
+    CacheControl? cacheControl = null;
+
+    var action = () => new ImageContent(source, cacheControl!);
+
+    action.Should().Throw<ArgumentNullException>();
+  }
+
   [Fact]
   public void JsonSerialization_WhenSerialized_ItShouldHaveExpectedShape()
   {

tests/AnthropicClient.Tests/Unit/Models/SourceTypeTests.cs

@@ -19,4 +19,10 @@ public class SourceTypeTests
   {
     SourceType.Text.Should().Be("text");
   }
+
+  [Fact]
+  public void File_WhenCalled_ItShouldReturnCorrectValue()
+  {
+    SourceType.File.Should().Be("file");
+  }
 }

tests/AnthropicClient.Tests/Unit/Models/UrlSourceTests.cs

@@ -0,0 +1,64 @@
+namespace AnthropicClient.Tests.Unit.Models;
+
+public class UrlSourceTests : SerializationTest
+{
+  private readonly string _testJson = @"{
+    ""type"": ""url"",
+    ""url"": ""https://example.com/document.pdf""
+  }";
+
+  [Fact]
+  public void Constructor_WhenCalled_ItShouldInitializeProperties()
+  {
+    var result = new UrlSource();
+
+    result.Url.Should().BeEmpty();
+    result.Type.Should().Be("url");
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithValues_ItShouldInitializeProperties()
+  {
+    var url = "https://example.com/document.pdf";
+    var type = "type";
+
+    var result = new UrlSource()
+    {
+      Url = url,
+      Type = type,
+    };
+
+    result.Url.Should().Be(url);
+    result.Type.Should().Be(type);
+  }
+
+  [Fact]
+  public void Constructor_WhenCalledWithUrl_ItShouldInitializeProperties()
+  {
+    var url = "https://example.com/document.pdf";
+
+    var result = new UrlSource(url);
+
+    result.Url.Should().Be(url);
+    result.Type.Should().Be("url");
+  }
+
+  [Fact]
+  public void JsonSerialization_WhenSerialized_ItShouldHaveExpectedShape()
+  {
+    var url = "https://example.com/document.pdf";
+    var source = new UrlSource(url);
+
+    var result = Serialize<Source>(source);
+
+    JsonAssert.Equal(_testJson, result);
+  }
+
+  [Fact]
+  public void JsonDeserialization_WhenDeserialized_ItShouldMatchExpectedObject()
+  {
+    var result = Deserialize<Source>(_testJson);
+
+    result.Should().BeEquivalentTo(new UrlSource("https://example.com/document.pdf"));
+  }
+}