From e373d993c1b3f61315dcc9280ee251c7a9b5e854 Mon Sep 17 00:00:00 2001
From: Andon Andonov <andon.andonov@microsoft.com>
Date: Fri, 21 Sep 2018 21:01:38 -0700
Subject: [PATCH] Add TryAdd and Clear regression tests

---
 .../Generic/Dictionary/Dictionary.Tests.cs    | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/System.Collections/tests/Generic/Dictionary/Dictionary.Tests.cs b/src/System.Collections/tests/Generic/Dictionary/Dictionary.Tests.cs
index 640205b269e1..53e488a86d7c 100644
--- a/src/System.Collections/tests/Generic/Dictionary/Dictionary.Tests.cs
+++ b/src/System.Collections/tests/Generic/Dictionary/Dictionary.Tests.cs
@@ -250,6 +250,31 @@ public void Remove_NonExistentEntries_DoesNotPreventEnumeration()
             }
         }
 
+        [Fact]
+        [Trait("MyTrait", "MyTraitValue")]
+        public void Clear_OnEmptyCollection_DoesNotInvalidateEnumerator()
+        {
+            Dictionary<string, string> dictionary = new Dictionary<string, string>();
+            var valuesEnum = dictionary.GetEnumerator();
+
+            dictionary.Clear();
+            Assert.Empty(dictionary);
+            valuesEnum.MoveNext();
+        }
+
+        [Fact]
+        [Trait("MyTrait", "MyTraitValue")]
+        public void Unsuccessful_TryAdd_DoesNotInvalidateEnumerator()
+        {
+            Dictionary<string, string> dictionary = new Dictionary<string, string>();
+            dictionary.Add("a", "b");
+
+            var valuesEnum = dictionary.GetEnumerator();
+            Assert.False(dictionary.TryAdd("a", "c")); 
+
+            valuesEnum.MoveNext();
+        }
+
         [Theory]
         [MemberData(nameof(CopyConstructorInt32Data))]
         public void CopyConstructorInt32(int size, Func<int, int> keyValueSelector, Func<IDictionary<int, int>, IDictionary<int, int>> dictionarySelector)