From 3ab20b658d4e07ebd8b3cf149fd06e5b71420248 Mon Sep 17 00:00:00 2001
From: Charlie Kindel <charlie@kindel.com>
Date: Mon, 8 Jun 2020 20:29:09 -0600
Subject: [PATCH] unit tests for topologicalsort errors

---
 UnitTests/ViewTests.cs | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/UnitTests/ViewTests.cs b/UnitTests/ViewTests.cs
index 059544090..f89cbf6d3 100644
--- a/UnitTests/ViewTests.cs
+++ b/UnitTests/ViewTests.cs
@@ -107,5 +107,33 @@ namespace Terminal.Gui {
 
 			// TODO: Add more
 		}
+
+		[Fact]
+		public void TopologicalSort_Missing_Add ()
+		{
+			var root = new View ();
+			var sub1 = new View ();
+			root.Add (sub1);
+			var sub2 = new View ();
+			sub1.Width = Dim.Width(sub2);
+
+			Assert.Throws<InvalidOperationException> (() => root.LayoutSubviews ());
+
+			sub2.Width = Dim.Width (sub1);
+
+			Assert.Throws<InvalidOperationException> (() => root.LayoutSubviews ());
+		}
+
+		[Fact]
+		public void TopologicalSort_Recursive_Ref ()
+		{
+			var root = new View ();
+			var sub1 = new View ();
+			root.Add (sub1);
+			var sub2 = new View ();
+			root.Add (sub2);
+			sub2.Width = Dim.Width (sub2);
+			Assert.Throws<InvalidOperationException> (() => root.LayoutSubviews ());
+		}
 	}
 }