Imported Upstream version 3.8.0

Former-commit-id: 6a76a29bd07d86e57c6c8da45c65ed5447d38a61

mcs/class/corlib/Test/System.Collections.Concurrent/ConcurrentQueueTests.cs

@@ -30,6 +30,7 @@ using System.Collections.Generic;
 using System.Collections.Concurrent;
 
 using NUnit.Framework;
+using MonoTests.System.Threading.Tasks;
 
 namespace MonoTests.System.Collections.Concurrent
 {
@@ -115,6 +116,34 @@ namespace MonoTests.System.Collections.Concurrent
 			CollectionStressTestHelper.RemoveStressTest (new ConcurrentQueue<int> (), CheckOrderingType.InOrder);
 		}
 		
+		[Test]
+		public void StressTryPeekTestCase ()
+		{
+			ParallelTestHelper.Repeat (delegate {
+				var queue = new ConcurrentQueue<object> ();
+				queue.Enqueue (new object());
+				
+				const int threads = 10;
+				int threadCounter = 0;
+				bool success = true;
+				
+				ParallelTestHelper.ParallelStressTest (queue, (q) => {
+					int threadId = Interlocked.Increment (ref threadCounter);
+					object temp;
+					if (threadId < threads)
+					{
+						while (queue.TryPeek (out temp))
+							if (temp == null)
+								success = false;
+					} else {
+						queue.TryDequeue (out temp);
+					}
+				}, threads);
+				
+				Assert.IsTrue (success, "TryPeek returned unexpected null value.");
+			}, 10);
+		}
+		
 		[Test]
 		public void CountTestCase()
 		{
@@ -215,6 +244,30 @@ namespace MonoTests.System.Collections.Concurrent
 		{
 			queue.CopyTo (new int[3], 0);
 		}
+
+		static WeakReference CreateWeakReference (object obj)
+		{
+			return new WeakReference (obj);
+		}
+
+		[Test]
+		// This depends on precise stack scanning
+		[Category ("NotWorking")]
+		public void TryDequeueReferenceTest ()
+		{
+			var obj = new Object ();
+			var weakReference = CreateWeakReference(obj);
+			var queue = new ConcurrentQueue<object> ();
+
+			queue.Enqueue (obj);
+			queue.TryDequeue (out obj);
+			obj = null;
+
+			GC.Collect ();
+			GC.WaitForPendingFinalizers ();
+
+			Assert.IsFalse (weakReference.IsAlive);
+		}
 	}
 }
 #endif