From 878e9c1fa705e090e9ecdf4b2d37a0511496403f Mon Sep 17 00:00:00 2001
From: Reuben Swartz <reuben_swartz@wycliffeassociates.org>
Date: Wed, 11 Sep 2024 15:57:44 -0400
Subject: [PATCH] Fix a case where an exception is possible in
 GetHierarchyToMultipleMarkers (#144)

---
 USFMToolsSharp/Models/Markers/Marker.cs | 9 +++++++++
 USFMToolsSharpTest/USFMParserTest.cs    | 7 ++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/USFMToolsSharp/Models/Markers/Marker.cs b/USFMToolsSharp/Models/Markers/Marker.cs
index f9b7774..1f3109a 100644
--- a/USFMToolsSharp/Models/Markers/Marker.cs
+++ b/USFMToolsSharp/Models/Markers/Marker.cs
@@ -114,6 +114,15 @@ public List<Marker> GetHierarchyToMarker(Marker target)
         /// <remarks>In the case that the marker doesn't exist in the tree the dictionary will contain an empty list for that marker</remarks>
         public Dictionary<Marker, List<Marker>> GetHierachyToMultipleMarkers(List<Marker> targets)
         {
+            if (targets.Count == 0)
+            {
+                return new Dictionary<Marker, List<Marker>>();
+            }
+            if (Contents.Count == 0)
+            {
+                return targets.ToDictionary(i => i, i => new List<Marker>());
+            }
+            
             Dictionary<Marker, List<Marker>> output = new Dictionary<Marker, List<Marker>>(targets.Count);
             var parents = new Stack<(Marker marker, bool isLastInParent)>();
             int childMarkerContentsCount;
diff --git a/USFMToolsSharpTest/USFMParserTest.cs b/USFMToolsSharpTest/USFMParserTest.cs
index 39a42d6..bf8c48d 100644
--- a/USFMToolsSharpTest/USFMParserTest.cs
+++ b/USFMToolsSharpTest/USFMParserTest.cs
@@ -776,8 +776,13 @@ public void TestGetHierarchyToMultipleMarkers()
             var textInFootnote = new TextBlock("Text in footnote");
             var secondBlock = new TextBlock("Hello again");
             var nonExistant = new VMarker();
+            var result = document.GetHierachyToMultipleMarkers(new List<Marker>());
+            Assert.AreEqual(0, result.Count);
+            result = document.GetHierachyToMultipleMarkers(new List<Marker>() {footnote});
+            Assert.AreEqual(1, result.Count);
+            Assert.AreEqual(0, result[footnote].Count);
             document.InsertMultiple(new Marker[] { chapter, verse, textblock, footnote, footnoteText, textInFootnote, footnoteEndMarker, secondBlock });
-            var result = document.GetHierachyToMultipleMarkers(new List<Marker>() { textblock, secondBlock, nonExistant, textInFootnote });
+            result = document.GetHierachyToMultipleMarkers(new List<Marker>() { textblock, secondBlock, nonExistant, textInFootnote });
             Assert.AreEqual(document, result[textblock][0]);
             Assert.AreEqual(chapter, result[textblock][1]);
             Assert.AreEqual(verse, result[textblock][2]);