test(cutting): share the lead-in tests' point and profile helpers

Three lead-in test classes kept identical AssertPoint and Profile
helpers. They now import LeadInTestHelpers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

OpenNest.Tests/CuttingStrategy/ArcLeadInTangentTests.cs

@@ -2,6 +2,7 @@ using OpenNest.CNC;
 using OpenNest.CNC.CuttingStrategy;
 using OpenNest.Geometry;
 using OpenNest.Math;
+using static OpenNest.Tests.CuttingStrategy.LeadInTestHelpers;
 
 namespace OpenNest.Tests.CuttingStrategy;
 
@@ -168,9 +169,6 @@ public class ArcLeadInTangentTests
             program.Codes.Add(new LinearMove(point));
     }
 
-    private static ShapeProfile Profile(Part part) => new(part.Program.ToGeometry()
-        .Where(e => SpecialLayers.IsMaterial(e.Layer)).ToList());
-
     private static IEnumerable<Entity> Leads(Part part, Layer layer) =>
         part.Program.ToGeometry().Where(e => e.Layer == layer);
 
@@ -182,10 +180,4 @@ public class ArcLeadInTangentTests
         var radial = (point - arc.Center).Normalize();
         return arc.IsReversed ? new Vector(radial.Y, -radial.X) : new Vector(-radial.Y, radial.X);
     }
-
-    private static void AssertPoint(Vector expected, Vector actual)
-    {
-        Assert.Equal(expected.X, actual.X, 8);
-        Assert.Equal(expected.Y, actual.Y, 8);
-    }
 }

OpenNest.Tests/CuttingStrategy/CutoutCornerLeadInTests.cs

@@ -1,6 +1,7 @@
 using OpenNest.CNC;
 using OpenNest.CNC.CuttingStrategy;
 using OpenNest.Geometry;
+using static OpenNest.Tests.CuttingStrategy.LeadInTestHelpers;
 
 namespace OpenNest.Tests.CuttingStrategy;
 
@@ -283,9 +284,6 @@ public class CutoutCornerLeadInTests
             program.Codes.Add(new LinearMove(point));
     }
 
-    private static ShapeProfile Profile(Part part) => new(part.Program.ToGeometry()
-        .Where(e => SpecialLayers.IsMaterial(e.Layer)).ToList());
-
     private static Shape Cutout(Part part) => Assert.Single(Profile(part).Cutouts);
 
     private static Line SingleLeadIn(Part part) => Assert.IsType<Line>(Assert.Single(
@@ -297,10 +295,4 @@ public class CutoutCornerLeadInTests
         AssertPoint(corner + direction / direction.DistanceTo(Vector.Zero) * LeadLength, lead.StartPoint);
         Assert.Equal(LeadLength, lead.Length, 8);
     }
-
-    private static void AssertPoint(Vector expected, Vector actual)
-    {
-        Assert.Equal(expected.X, actual.X, 8);
-        Assert.Equal(expected.Y, actual.Y, 8);
-    }
 }

OpenNest.Tests/CuttingStrategy/LeadInTestHelpers.cs

@@ -0,0 +1,20 @@
+using OpenNest.CNC;
+using OpenNest.CNC.CuttingStrategy;
+using OpenNest.Geometry;
+
+namespace OpenNest.Tests.CuttingStrategy;
+
+/// <summary>Helpers the lead-in tests share. Import with <c>using static</c>.</summary>
+internal static class LeadInTestHelpers
+{
+    /// <summary>Asserts both coordinates match to 8 decimal places.</summary>
+    public static void AssertPoint(Vector expected, Vector actual)
+    {
+        Assert.Equal(expected.X, actual.X, 8);
+        Assert.Equal(expected.Y, actual.Y, 8);
+    }
+
+    /// <summary>The part's shape profile, leaving out rapid, scribe and break layers.</summary>
+    public static ShapeProfile Profile(Part part) => new(part.Program.ToGeometry()
+        .Where(e => SpecialLayers.IsMaterial(e.Layer)).ToList());
+}

OpenNest.Tests/CuttingStrategy/PerimeterCornerLeadInTests.cs

@@ -1,6 +1,7 @@
 using OpenNest.CNC;
 using OpenNest.CNC.CuttingStrategy;
 using OpenNest.Geometry;
+using static OpenNest.Tests.CuttingStrategy.LeadInTestHelpers;
 
 namespace OpenNest.Tests.CuttingStrategy;
 
@@ -254,9 +255,6 @@ public class PerimeterCornerLeadInTests
             program.Codes.Add(new LinearMove(point));
     }
 
-    private static ShapeProfile Profile(Part part) => new(part.Program.ToGeometry()
-        .Where(e => SpecialLayers.IsMaterial(e.Layer)).ToList());
-
     private static Shape Perimeter(Part part)
     {
         var perimeter = Profile(part).Perimeter;
@@ -275,10 +273,4 @@ public class PerimeterCornerLeadInTests
 
     private static Line SingleLead(Part part, Layer layer) => Assert.IsType<Line>(Assert.Single(
         part.Program.ToGeometry().Where(e => e.Layer == layer)));
-
-    private static void AssertPoint(Vector expected, Vector actual)
-    {
-        Assert.Equal(expected.X, actual.X, 8);
-        Assert.Equal(expected.Y, actual.Y, 8);
-    }
 }