Added ConcurrentDictionary.Comparer property (#47787)

* fix #31350 * fix ref file * fix getter * added tests
dotnet · Feb 3, 2021 · 9f921f4 · 9f921f4
1 parent fabaed2
commit 9f921f4
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diff --git a/src/libraries/System.Collections.Concurrent/ref/System.Collections.Concurrent.cs b/src/libraries/System.Collections.Concurrent/ref/System.Collections.Concurrent.cs
@@ -82,6 +82,7 @@ public ConcurrentDictionary(System.Collections.Generic.IEqualityComparer<TKey>?
         public ConcurrentDictionary(int concurrencyLevel, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey, TValue>> collection, System.Collections.Generic.IEqualityComparer<TKey>? comparer) { }
         public ConcurrentDictionary(int concurrencyLevel, int capacity) { }
         public ConcurrentDictionary(int concurrencyLevel, int capacity, System.Collections.Generic.IEqualityComparer<TKey>? comparer) { }
+        public System.Collections.Generic.IEqualityComparer<TKey> Comparer { get { throw null; } }
         public int Count { get { throw null; } }
         public bool IsEmpty { get { throw null; } }
         public TValue this[TKey key] { get { throw null; } set { } }

diff --git a/...s/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentDictionary.cs b/...s/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentDictionary.cs
@@ -1051,6 +1051,8 @@ public TValue this[TKey key]
         private static void ThrowKeyNotFoundException(TKey key) =>
             throw new KeyNotFoundException(SR.Format(SR.Arg_KeyNotFoundWithKey, key.ToString()));
 
+        public IEqualityComparer<TKey> Comparer => _comparer ?? _defaultComparer;
+
         /// <summary>
         /// Gets the number of key/value pairs contained in the <see
         /// cref="ConcurrentDictionary{TKey,TValue}"/>.

diff --git a/...ies/System.Collections.Concurrent/tests/ConcurrentDictionary/ConcurrentDictionaryTests.cs b/...ies/System.Collections.Concurrent/tests/ConcurrentDictionary/ConcurrentDictionaryTests.cs
@@ -666,6 +666,24 @@ void AssertDefaultComparerBehavior(ConcurrentDictionary<EqualityApiSpy, int> dic
             }
         }
 
+        [Fact]
+        public static void TestComparerGetter()
+        {
+            AssertComparerBehavior<string>(null);
+            AssertComparerBehavior<string>(EqualityComparer<string>.Default);
+            AssertComparerBehavior<string>(StringComparer.InvariantCulture);
+            AssertComparerBehavior<string>(StringComparer.OrdinalIgnoreCase);
+            AssertComparerBehavior<int>(EqualityComparer<int>.Default);
+            AssertComparerBehavior<bool>(EqualityComparer<bool>.Default);
+
+            void AssertComparerBehavior<T>(IEqualityComparer<T> comparer)
+            {
+                var dc = new ConcurrentDictionary<T, object>(comparer);
+                object expected = comparer ?? EqualityComparer<T>.Default;
+                Assert.Same(expected, dc.Comparer);
+            }
+        }
+
         private sealed class EqualityApiSpy : IEquatable<EqualityApiSpy>
         {
             public bool ObjectApiUsed { get; private set; }