Implement basic unit test infrastructure with abstraction patterns

Co-authored-by: ngenovese11 <23391587+ngenovese11@users.noreply.github.com>

tests/PepperDash.Essentials.Core.Tests/Abstractions/IQueue.cs

@@ -0,0 +1,28 @@
+using System;
+
+namespace PepperDash.Essentials.Core.Tests.Abstractions
+{
+    /// <summary>
+    /// Abstraction for queue operations to enable testing
+    /// </summary>
+    /// <typeparam name="T">Type of items in the queue</typeparam>
+    public interface IQueue<T>
+    {
+        /// <summary>
+        /// Number of items in the queue
+        /// </summary>
+        int Count { get; }
+        
+        /// <summary>
+        /// Adds an item to the queue
+        /// </summary>
+        /// <param name="item">Item to add</param>
+        void Enqueue(T item);
+        
+        /// <summary>
+        /// Removes and returns the next item from the queue
+        /// </summary>
+        /// <returns>The next item, or default(T) if queue is empty</returns>
+        T Dequeue();
+    }
+}