diff --git a/src/Reveal.Sdk.Dom.Tests/Visualizations/Extensions/ICategoryExtensionsFixture.cs b/src/Reveal.Sdk.Dom.Tests/Visualizations/Extensions/ICategoryExtensionsFixture.cs
new file mode 100644
index 00000000..96f2b9c2
--- /dev/null
+++ b/src/Reveal.Sdk.Dom.Tests/Visualizations/Extensions/ICategoryExtensionsFixture.cs
@@ -0,0 +1,52 @@
+using Moq;
+using Reveal.Sdk.Dom.Visualizations;
+using Xunit;
+
+namespace Reveal.Sdk.Dom.Tests.Visualizations.Extensions
+{
+    public class ICategoryExtensionsFixture
+    {
+        [Fact]
+        public void SetCategory_UpdateCategory_WithFieldName()
+        {
+            // Arrange
+            var visualization = new MockICategory();
+            var fieldName = "TestField";
+            var expectedCategory = new DimensionColumn()
+            {
+                DataField = new TextDataField(fieldName)
+            };
+
+            // Act
+            visualization.SetCategory(fieldName);
+
+            // Assert
+            Assert.Equivalent(expectedCategory, visualization.Category);
+        }
+
+        [Fact]
+        public void SetCategory_UpdateCategory_WithDimensionDataField()
+        {
+            // Arrange
+            var visualization = new MockICategory();
+            var fieldName = "TestField";
+            var mockDimensionDataField = new Mock<DimensionDataField>(fieldName);
+            var field = mockDimensionDataField.Object;
+            var expectedCategory = new DimensionColumn()
+            {
+                DataField = field
+            };
+
+            // Act
+            visualization.SetCategory(field);
+
+            // Assert
+            Assert.Equivalent(expectedCategory, visualization.Category);
+        }
+
+        private class MockICategory : ICategory
+        {
+            public DimensionColumn Category { get; set; }
+        }
+    }
+}