added test cases for codecov

Author: mohit-gogitter

DataStructures.Tests/LinkedList/CircularLinkedListTests.cs

@@ -1,5 +1,6 @@
 using System;
 using DataStructures.LinkedList.CircularLinkedList;
+using Microsoft.VisualStudio.TestPlatform.Utilities;
 using NUnit.Framework;
 
 namespace DataStructures.Tests.LinkedList;
@@ -18,6 +19,15 @@ public static void TestDisplay()
         Assert.That("10 20 30", Is.EqualTo(GetDisplayOutput(cll).Trim()));
     }
 
+    [Test]
+    public static void TestDisplayEmptyList()
+    {
+        var cll = new CircularLinkedList<int>();
+        cll.Display();
+
+        Assert.That("List is empty.", Is.EqualTo(GetDisplayOutput(cll).Trim()));
+    }
+
     [Test]
     public static void TestInsertAtBeginning()
     {
@@ -69,6 +79,17 @@ public static void TestInsertAtEndInEmptyList()
         Assert.That("10", Is.EqualTo(GetDisplayOutput(cll).Trim()));
     }
 
+    [Test]
+    public static void TestInsertAfterInEmptyList()
+    {
+        var cll = new CircularLinkedList<int>();
+        cll.InsertAfter(10, 20);
+
+        Assert.That("List is empty.", Is.EqualTo(GetDisplayOutput(cll).Trim()));
+    }
+
+
+
     [Test]
     public static void TestInsertAfterSpecificNode()
     {