tests: adding missing tests for newly introduced classes

src/AnthropicClient/Models/CharacterLocationCitation.cs

@@ -18,4 +18,12 @@ public class CharacterLocationCitation : Citation
   /// </summary>
   [JsonPropertyName("end_char_index")]
   public int EndCharIndex { get; init; }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="CharacterLocationCitation"/> class.
+  /// </summary>
+  /// <returns>A new instance of <see cref="CharacterLocationCitation"/>.</returns>
+  public CharacterLocationCitation() : base(CitationType.CharacterLocation)
+  {
+  }
 }

src/AnthropicClient/Models/Citation.cs

@@ -29,4 +29,19 @@ public abstract class Citation
   /// </summary>
   [JsonPropertyName("document_title")]
   public string DocumentTitle { get; init; } = string.Empty;
+
+  [JsonConstructor]
+  internal Citation()
+  {
+  }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="Citation"/> class with a specified type.
+  /// </summary>
+  /// <param name="type">The type of the citation.</param>
+  /// <returns>A new instance of <see cref="Citation"/>.</returns>
+  protected Citation(string type)
+  {
+    Type = type;
+  }
 }

src/AnthropicClient/Models/CitationDelta.cs

@@ -22,6 +22,9 @@ public class CitationDelta : ContentDelta
   /// <summary>
   /// Initializes a new instance of the <see cref="CitationDelta"/> class.
   /// </summary>
+  /// <param name="citation">The citation to associate with this delta.</param>
+  /// <exception cref="ArgumentNullException">Thrown when <paramref name="citation"/> is null.</exception>
+  /// <returns>A new instance of <see cref="CitationDelta"/>.</returns>
   public CitationDelta(Citation citation) : base(ContentDeltaType.CitationDelta)
   {
     ArgumentValidator.ThrowIfNull(citation, nameof(citation));

src/AnthropicClient/Models/ContentBlockLocationCitation.cs

@@ -18,4 +18,12 @@ public class ContentBlockLocationCitation : Citation
   /// </summary>
   [JsonPropertyName("end_block_index")]
   public int EndBlockIndex { get; init; }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="ContentBlockLocationCitation"/> class.
+  /// </summary>
+  /// <returns>A new instance of <see cref="ContentBlockLocationCitation"/>.</returns>
+  public ContentBlockLocationCitation() : base(CitationType.ContentBlockLocation)
+  {
+  }
 }

src/AnthropicClient/Models/PageLocationCitation.cs

@@ -18,4 +18,12 @@ public class PageLocationCitation : Citation
   /// </summary>
   [JsonPropertyName("end_page_number")]
   public int EndPageNumber { get; init; }
+
+  /// <summary>
+  /// Initializes a new instance of the <see cref="PageLocationCitation"/> class.
+  /// </summary>
+  /// <returns>A new instance of <see cref="PageLocationCitation"/>.</returns>
+  public PageLocationCitation() : base(CitationType.PageLocation)
+  {
+  }
 }