From 19ec7c78a1d443c78ccd91937ac16b3da3576b7d Mon Sep 17 00:00:00 2001
From: Roy Stogner <Roy.Stogner@inl.gov>
Date: Tue, 15 Mar 2022 20:37:14 -0500
Subject: [PATCH] ConcaveBoundaryTest unit test

This is from the case I originally got to trigger the problem.  We could
probably boil it down to something smaller (by temporarily reverting the
Orient2d change to make sure the failure still occurs) but this doesn't
seem too bloated for a unit test as-is.
---
 unittest/main.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/unittest/main.cpp b/unittest/main.cpp
index 3697c7e..dc86f4a 100644
--- a/unittest/main.cpp
+++ b/unittest/main.cpp
@@ -67,6 +67,52 @@ BOOST_AUTO_TEST_CASE(NarrowQuadTest)
   }
 }
 
+BOOST_AUTO_TEST_CASE(ConcaveBoundaryTest)
+{
+  // Concave-by-less-than-epsilon boundaries used to potentially fail
+  // during triangulation
+  const double eps = 1e-15; // This gave EdgeEvent - null triangle
+  std::vector<p2t::Point*> polyline {
+    new p2t::Point(0,0),
+    new p2t::Point(0.5,eps),
+    new p2t::Point(1,0),
+    new p2t::Point(1-eps,0.836541),
+    new p2t::Point(1,2),
+    new p2t::Point(.46,1.46+eps),
+    new p2t::Point(0,1),
+    new p2t::Point(eps,0.5)
+  };
+
+  const double r2o4 = std::sqrt(2.)/4;
+  std::vector<p2t::Point*> hole {
+    new p2t::Point(0.5+r2o4,0.5),
+    new p2t::Point(0.5,0.5+r2o4),
+    new p2t::Point(0.5-r2o4,0.5),
+    new p2t::Point(0.5-eps,0.5-r2o4)
+  };
+
+  std::vector<p2t::Point> interior_points
+    {{0.21,0.79},{0.21,0.21},{0.79,0.21}};
+
+  p2t::CDT cdt{ polyline };
+  cdt.AddHole(hole);
+
+  for (auto & p : interior_points)
+    cdt.AddPoint(&p);
+
+  BOOST_CHECK_NO_THROW(cdt.Triangulate());
+  const auto result = cdt.GetTriangles();
+  BOOST_REQUIRE_EQUAL(result.size(), 18);
+  BOOST_CHECK(p2t::IsDelaunay(result));
+  for (const auto p : polyline) {
+    delete p;
+  }
+  for (const auto p : hole) {
+    delete p;
+  }
+}
+
+
 BOOST_AUTO_TEST_CASE(TestbedFilesTest)
 {
   for (const auto& filename : { "custom.dat", "diamond.dat", "star.dat", "test.dat" }) {