Added Unit test and modified ErrorKeyNames.cs

src/ApiResponse/ErrorKeyNames.cs

@@ -4,6 +4,6 @@ public static class ErrorKeyNames
 {
     public const string Conflict = "conflict";
     public const string Validation = "validation";
-    public const string NotFound = "not-found";
+    public const string NotFound = "notfound";
 
 }

tests/Unit/ListResponseTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
@@ -43,8 +44,27 @@ public void Should_set_and_get_properties()
 
 
         }
-    }
+
+        [Theory, Description("Ensure ListResponse has properties defined")]
+        [InlineData("Items", typeof(List<DummyListResponseClass>))]
+        [InlineData("Size", typeof(int))]
+        [InlineData("Page", typeof(int))]
+        [InlineData("PerPage", typeof(int))]
+        [InlineData("TotalPages", typeof(int))]
+        [InlineData("HasPrevious", typeof(bool))]
+        [InlineData("HasNext", typeof(bool))]
+        public void Should_have_base_fields_defined(string name, Type type)
+        {
+            var testClass = typeof(ListResponse<DummyListResponseClass>);
+            var prop = testClass.GetProperty(name);
 
+            prop.ShouldSatisfyAllConditions(
+                () => prop.ShouldNotBeNull(),
+                () => prop?.PropertyType.ShouldBeEquivalentTo(type)
+            );
+        }
+    }
+
     public class DummyListResponseClass
     {
         public string Name { get; set; }

tests/Unit/SIngleResponseTests.cs

@@ -0,0 +1,27 @@
+using System;
+using System.ComponentModel;
+using Shouldly;
+using Xunit;
+
+namespace Threenine.ApiResponse.Tests;
+
+public class SIngleResponseTests
+{
+    [Theory, Description("Ensure SingleResponse has properties defined")]
+    [InlineData("Item", typeof(TestClass))]
+    public void Should_have_base_fields_defined(string name, Type type)
+    {
+        var testClass = typeof(SingleResponse<TestClass>);
+        var prop = testClass.GetProperty(name);
+
+        prop.ShouldSatisfyAllConditions(
+            () => prop.ShouldNotBeNull(),
+            () => prop?.PropertyType.ShouldBeEquivalentTo(type)
+        );
+    }
+}
+
+public class TestClass
+{
+
+}