Fixes #4374 - Nukes all (?) legacy Driver and Application stuff; revamps tests (#4376)

Tests/UnitTestsParallelizable/Drivers/WindowSizeMonitorTests.cs

@@ -0,0 +1,75 @@
+using Moq;
+
+namespace UnitTests_Parallelizable.DriverTests;
+
+public class WindowSizeMonitorTests
+{
+    [Fact]
+    public void TestWindowSizeMonitor_RaisesEventWhenChanges ()
+    {
+        Mock<IOutput> consoleOutput = new ();
+
+        Queue<Size> queue = new (
+                                 [
+                                     new (30, 20),
+                                     new (20, 20)
+                                 ]);
+
+        consoleOutput.Setup (m => m.GetSize ())
+                     .Returns (queue.Dequeue);
+
+        var outputBuffer = Mock.Of<IOutputBuffer> ();
+
+        var monitor = new SizeMonitorImpl (consoleOutput.Object);
+
+        List<SizeChangedEventArgs> result = [];
+        monitor.SizeChanged += (s, e) => { result.Add (e); };
+
+        Assert.Empty (result);
+        monitor.Poll ();
+
+        Assert.Single (result);
+        Assert.Equal (new Size (30, 20), result [0].Size);
+
+        monitor.Poll ();
+
+        Assert.Equal (2, result.Count);
+        Assert.Equal (new Size (30, 20), result [0].Size);
+        Assert.Equal (new Size (20, 20), result [1].Size);
+    }
+
+    [Fact]
+    public void TestWindowSizeMonitor_DoesNotRaiseEventWhen_NoChanges ()
+    {
+        Mock<IOutput> consoleOutput = new ();
+
+        Queue<Size> queue = new (
+                                 [
+                                     new (30, 20),
+                                     new (30, 20)
+                                 ]);
+
+        consoleOutput.Setup (m => m.GetSize ())
+                     .Returns (queue.Dequeue);
+
+        var outputBuffer = Mock.Of<IOutputBuffer> ();
+
+        var monitor = new SizeMonitorImpl (consoleOutput.Object);
+
+        List<SizeChangedEventArgs> result = [];
+        monitor.SizeChanged += (s, e) => { result.Add (e); };
+
+        // First poll always raises event because going from unknown size i.e. 0,0
+        Assert.Empty (result);
+        monitor.Poll ();
+
+        Assert.Single (result);
+        Assert.Equal (new Size (30, 20), result [0].Size);
+
+        // No change 
+        monitor.Poll ();
+
+        Assert.Single (result);
+        Assert.Equal (new Size (30, 20), result [0].Size);
+    }
+}