From 54d27b29a5793894806ce3ca22bbe70e0d62b353 Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Fri, 6 Nov 2020 05:33:25 -0500
Subject: [PATCH] Tweak StreamConformanceTests for cancellation (#44342)

- Avoid unnecessary timers
- Separate tests for precancellation, ReadAsync(byte[], ...) cancellation, and ReadAsync(Memory, ...) cancellation
---
 .../Tests/System/IO/StreamConformanceTests.cs      | 44 +++++++++++++++++-----
 1 file changed, 34 insertions(+), 10 deletions(-)

diff --git a/src/libraries/Common/tests/Tests/System/IO/StreamConformanceTests.cs b/src/libraries/Common/tests/Tests/System/IO/StreamConformanceTests.cs
index 309a340..47d12e7 100644
--- a/src/libraries/Common/tests/Tests/System/IO/StreamConformanceTests.cs
+++ b/src/libraries/Common/tests/Tests/System/IO/StreamConformanceTests.cs
@@ -532,23 +532,30 @@ namespace System.IO.Tests
             }
         }
 
-        protected async Task ValidateCancelableReads_AfterInvocation_ThrowsCancellationException(Stream stream)
+        protected async Task ValidateCancelableReadAsyncTask_AfterInvocation_ThrowsCancellationException(Stream stream)
         {
             if (!stream.CanRead || !FullyCancelableOperations)
             {
                 return;
             }
 
-            CancellationTokenSource cts;
-
-            cts = new CancellationTokenSource(1);
-            await AssertCanceledAsync(cts.Token, () => stream.ReadAsync(new byte[1], 0, 1, cts.Token));
+            var cts = new CancellationTokenSource();
+            Task<int> t = stream.ReadAsync(new byte[1], 0, 1, cts.Token);
+            cts.Cancel();
+            await AssertCanceledAsync(cts.Token, () => t);
+        }
 
-            if (UsableAfterCanceledReads)
+        protected async Task ValidateCancelableReadAsyncValueTask_AfterInvocation_ThrowsCancellationException(Stream stream)
+        {
+            if (!stream.CanRead || !FullyCancelableOperations)
             {
-                cts = new CancellationTokenSource(1);
-                await AssertCanceledAsync(cts.Token, async () => { await stream.ReadAsync(new Memory<byte>(new byte[1]), cts.Token); });
+                return;
             }
+
+            var cts = new CancellationTokenSource();
+            Task<int> t = stream.ReadAsync(new byte[1], cts.Token).AsTask();
+            cts.Cancel();
+            await AssertCanceledAsync(cts.Token, () => t);
         }
 
         protected async Task WhenAllOrAnyFailed(Task task1, Task task2)
@@ -1624,18 +1631,35 @@ namespace System.IO.Tests
         }
 
         [Fact]
-        public virtual async Task ReadWriteAsync_Canceled_ThrowsOperationCanceledException()
+        public virtual async Task ReadWriteAsync_PrecanceledOperations_ThrowsCancellationException()
         {
             using StreamPair streams = await CreateConnectedStreamsAsync();
 
             foreach (Stream stream in streams)
             {
                 await ValidatePrecanceledOperations_ThrowsCancellationException(stream);
-                await ValidateCancelableReads_AfterInvocation_ThrowsCancellationException(stream);
             }
         }
 
         [Fact]
+        public virtual async Task ReadAsync_CancelPendingTask_ThrowsCancellationException()
+        {
+            using StreamPair streams = await CreateConnectedStreamsAsync();
+            (Stream writeable, Stream readable) = GetReadWritePair(streams);
+
+            await ValidateCancelableReadAsyncTask_AfterInvocation_ThrowsCancellationException(readable);
+        }
+
+        [Fact]
+        public virtual async Task ReadAsync_CancelPendingValueTask_ThrowsCancellationException()
+        {
+            using StreamPair streams = await CreateConnectedStreamsAsync();
+            (Stream writeable, Stream readable) = GetReadWritePair(streams);
+
+            await ValidateCancelableReadAsyncValueTask_AfterInvocation_ThrowsCancellationException(readable);
+        }
+
+        [Fact]
         public virtual async Task ReadWriteByte_Success()
         {
             using StreamPair streams = await CreateConnectedStreamsAsync();
-- 
2.7.4