test: add RemnantFinder tests (red)

OpenNest.Tests/RemnantFinderTests.cs

@@ -0,0 +1,125 @@
+using OpenNest.Geometry;
+
+namespace OpenNest.Tests;
+
+public class RemnantFinderTests
+{
+    [Fact]
+    public void EmptyPlate_ReturnsWholeWorkArea()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        var remnants = finder.FindRemnants();
+
+        Assert.Single(remnants);
+        Assert.Equal(100 * 100, remnants[0].Area(), 0.1);
+    }
+
+    [Fact]
+    public void SingleObstacle_InCorner_FindsLShapedRemnants()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(0, 0, 40, 40));
+        var remnants = finder.FindRemnants();
+
+        Assert.True(remnants.Count >= 2);
+        var largest = remnants[0];
+        Assert.Equal(60 * 100, largest.Area(), 0.1);
+    }
+
+    [Fact]
+    public void SingleObstacle_InCenter_FindsFourRemnants()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(30, 30, 40, 40));
+        var remnants = finder.FindRemnants();
+
+        Assert.True(remnants.Count >= 4);
+    }
+
+    [Fact]
+    public void MinDimension_FiltersSmallRemnants()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(0, 0, 95, 100));
+        var all = finder.FindRemnants(0);
+        var filtered = finder.FindRemnants(10);
+
+        Assert.True(all.Count > filtered.Count);
+        foreach (var r in filtered)
+        {
+            Assert.True(r.Width >= 10);
+            Assert.True(r.Length >= 10);
+        }
+    }
+
+    [Fact]
+    public void ResultsSortedByAreaDescending()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(0, 0, 50, 50));
+        var remnants = finder.FindRemnants();
+
+        for (var i = 1; i < remnants.Count; i++)
+            Assert.True(remnants[i - 1].Area() >= remnants[i].Area());
+    }
+
+    [Fact]
+    public void AddObstacle_UpdatesResults()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        var before = finder.FindRemnants();
+        Assert.Single(before);
+
+        finder.AddObstacle(new Box(0, 0, 50, 50));
+        var after = finder.FindRemnants();
+        Assert.True(after.Count > 1);
+    }
+
+    [Fact]
+    public void ClearObstacles_ResetsToFullWorkArea()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(0, 0, 50, 50));
+        finder.ClearObstacles();
+        var remnants = finder.FindRemnants();
+
+        Assert.Single(remnants);
+        Assert.Equal(100 * 100, remnants[0].Area(), 0.1);
+    }
+
+    [Fact]
+    public void FullyCovered_ReturnsEmpty()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(0, 0, 100, 100));
+        var remnants = finder.FindRemnants();
+
+        Assert.Empty(remnants);
+    }
+
+    [Fact]
+    public void MultipleObstacles_FindsGapBetween()
+    {
+        var finder = new RemnantFinder(new Box(0, 0, 100, 100));
+        finder.AddObstacle(new Box(0, 0, 40, 100));
+        finder.AddObstacle(new Box(60, 0, 40, 100));
+        var remnants = finder.FindRemnants();
+
+        var gap = remnants.FirstOrDefault(r =>
+            r.Width >= 19.9 && r.Width <= 20.1 &&
+            r.Length >= 99.9);
+        Assert.NotNull(gap);
+    }
+
+    [Fact]
+    public void FromPlate_CreatesFinderWithPartsAsObstacles()
+    {
+        var plate = TestHelpers.MakePlate(60, 120,
+            TestHelpers.MakePartAt(0, 0, 20));
+        var finder = RemnantFinder.FromPlate(plate);
+        var remnants = finder.FindRemnants();
+
+        Assert.True(remnants.Count >= 1);
+        Assert.True(remnants[0].Area() < plate.WorkArea().Area());
+    }
+}