fix: improve chart performance with large datasets using LTTB downsampling

Daqifi.Desktop.Test/Loggers/CircularBufferTests.cs

@@ -0,0 +1,141 @@
+using Daqifi.Desktop.Logger;
+
+namespace Daqifi.Desktop.Test.Loggers;
+
+[TestClass]
+public class CircularBufferTests
+{
+    #region Constructor Tests
+    [TestMethod]
+    public void Constructor_ZeroCapacity_Throws()
+    {
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => new CircularBuffer<int>(0));
+    }
+
+    [TestMethod]
+    public void Constructor_ValidCapacity_CreatesEmptyBuffer()
+    {
+        var buffer = new CircularBuffer<int>(10);
+        Assert.AreEqual(0, buffer.Count);
+        Assert.AreEqual(10, buffer.Capacity);
+    }
+    #endregion
+
+    #region Add and Count Tests
+    [TestMethod]
+    public void Add_BelowCapacity_IncrementsCount()
+    {
+        var buffer = new CircularBuffer<int>(5);
+        buffer.Add(1);
+        buffer.Add(2);
+        buffer.Add(3);
+        Assert.AreEqual(3, buffer.Count);
+    }
+
+    [TestMethod]
+    public void Add_AtCapacity_CountStaysAtCapacity()
+    {
+        var buffer = new CircularBuffer<int>(3);
+        buffer.Add(1);
+        buffer.Add(2);
+        buffer.Add(3);
+        buffer.Add(4);
+        Assert.AreEqual(3, buffer.Count);
+    }
+    #endregion
+
+    #region Indexer Tests
+    [TestMethod]
+    public void Indexer_BelowCapacity_ReturnsCorrectItems()
+    {
+        var buffer = new CircularBuffer<int>(5);
+        buffer.Add(10);
+        buffer.Add(20);
+        buffer.Add(30);
+        Assert.AreEqual(10, buffer[0]);
+        Assert.AreEqual(20, buffer[1]);
+        Assert.AreEqual(30, buffer[2]);
+    }
+
+    [TestMethod]
+    public void Indexer_AfterWraparound_ReturnsOldestFirst()
+    {
+        var buffer = new CircularBuffer<int>(3);
+        buffer.Add(1);
+        buffer.Add(2);
+        buffer.Add(3);
+        buffer.Add(4); // Overwrites 1
+        buffer.Add(5); // Overwrites 2
+
+        Assert.AreEqual(3, buffer[0]); // Oldest surviving
+        Assert.AreEqual(4, buffer[1]);
+        Assert.AreEqual(5, buffer[2]); // Newest
+    }
+
+    [TestMethod]
+    public void Indexer_OutOfRange_Throws()
+    {
+        var buffer = new CircularBuffer<int>(5);
+        buffer.Add(1);
+        Assert.ThrowsExactly<ArgumentOutOfRangeException>(() => buffer[1]);
+    }
+    #endregion
+
+    #region ToList Tests
+    [TestMethod]
+    public void ToList_BelowCapacity_ReturnsAllItems()
+    {
+        var buffer = new CircularBuffer<int>(5);
+        buffer.Add(10);
+        buffer.Add(20);
+        var list = buffer.ToList();
+        CollectionAssert.AreEqual(new[] { 10, 20 }, list);
+    }
+
+    [TestMethod]
+    public void ToList_AfterWraparound_ReturnsInInsertionOrder()
+    {
+        var buffer = new CircularBuffer<int>(3);
+        for (var i = 1; i <= 7; i++)
+        {
+            buffer.Add(i);
+        }
+
+        var list = buffer.ToList();
+        CollectionAssert.AreEqual(new[] { 5, 6, 7 }, list);
+    }
+
+    [TestMethod]
+    public void ToList_Empty_ReturnsEmptyList()
+    {
+        var buffer = new CircularBuffer<int>(5);
+        var list = buffer.ToList();
+        Assert.AreEqual(0, list.Count);
+    }
+    #endregion
+
+    #region Clear Tests
+    [TestMethod]
+    public void Clear_ResetsCountToZero()
+    {
+        var buffer = new CircularBuffer<int>(5);
+        buffer.Add(1);
+        buffer.Add(2);
+        buffer.Clear();
+        Assert.AreEqual(0, buffer.Count);
+    }
+
+    [TestMethod]
+    public void Clear_AllowsReuse()
+    {
+        var buffer = new CircularBuffer<int>(3);
+        buffer.Add(1);
+        buffer.Add(2);
+        buffer.Add(3);
+        buffer.Clear();
+        buffer.Add(10);
+        Assert.AreEqual(1, buffer.Count);
+        Assert.AreEqual(10, buffer[0]);
+    }
+    #endregion
+}