Dev/automation/pool blocking tests on main

src/Microsoft.Data.SqlClient/src/Microsoft/Data/Common/AdapterUtil.cs

@@ -175,6 +175,28 @@ internal static Timer UnsafeCreateTimer(TimerCallback callback, object state, Ti
             }
         }
 
+        /// <summary>
+        /// Creates an <see cref="ITimer"/> using the supplied <see cref="TimeProvider"/> without
+        /// capturing the current <see cref="ExecutionContext"/>.
+        /// </summary>
+        internal static ITimer UnsafeCreateTimer<T>(
+            TimeProvider timeProvider,
+            Action<T> callback,
+            T state,
+            TimeSpan dueTime,
+            TimeSpan period)
+        {
+            if (ExecutionContext.IsFlowSuppressed())
+            {
+                return timeProvider.CreateTimer(s => callback((T)s), state, dueTime, period);
+            }
+
+            using (ExecutionContext.SuppressFlow())
+            {
+                return timeProvider.CreateTimer(s => callback((T)s), state, dueTime, period);
+            }
+        }
+
 
 #region COM+ exceptions
         internal static ArgumentException Argument(string error)

src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/WaitHandleDbConnectionPool.cs

@@ -198,7 +198,11 @@ public void Dispose()
         private volatile bool _errorOccurred;
 
         private int _errorWait;
-        private Timer _errorTimer;
+        private ITimer _errorTimer;
+
+        // Clock used to create the error backoff timer. Defaults to the system clock in
+        // production; tests inject a fake clock to drive the exit timer deterministically.
+        private readonly TimeProvider _timeProvider;
 
         private Timer _cleanupTimer;
 
@@ -212,7 +216,8 @@ internal WaitHandleDbConnectionPool(
             SqlConnectionFactory connectionFactory,
             DbConnectionPoolGroup connectionPoolGroup,
             DbConnectionPoolIdentity identity,
-            DbConnectionPoolProviderInfo connectionPoolProviderInfo)
+            DbConnectionPoolProviderInfo connectionPoolProviderInfo,
+            TimeProvider timeProvider = null)
         {
             Debug.Assert(connectionPoolGroup != null, "null connectionPoolGroup");
 
@@ -249,6 +254,7 @@ internal WaitHandleDbConnectionPool(
             _connectionPoolGroupOptions = connectionPoolGroup.PoolGroupOptions;
             _connectionPoolProviderInfo = connectionPoolProviderInfo;
             _identity = identity;
+            _timeProvider = timeProvider ?? TimeProvider.System;
 
             _waitHandles = new PoolWaitHandles();
 
@@ -597,7 +603,7 @@ private DbConnectionInternal CreateObject(DbConnection owningObject, DbConnectio
                 _resError = e;
 
                 // Make sure the timer starts even if ThreadAbort occurs after setting the ErrorEvent.
-                Timer t = new Timer(new TimerCallback(this.ErrorCallback), null, Timeout.Infinite, Timeout.Infinite);
+                ITimer t = ADP.UnsafeCreateTimer(_timeProvider, state => state.ErrorCallback(null), this, Timeout.InfiniteTimeSpan, Timeout.InfiniteTimeSpan);
 
                 bool timerIsNotDisposed;
 
@@ -608,7 +614,7 @@ private DbConnectionInternal CreateObject(DbConnection owningObject, DbConnectio
                 // Note that the timer is created to allow periodic invocation. If ThreadAbort occurs in the middle of ErrorCallback,
                 // the timer will restart. Otherwise, the timer callback (ErrorCallback) destroys the timer after resetting the error to avoid second callback.
                 _errorTimer = t;
-                timerIsNotDisposed = t.Change(_errorWait, _errorWait);
+                timerIsNotDisposed = t.Change(TimeSpan.FromMilliseconds(_errorWait), TimeSpan.FromMilliseconds(_errorWait));
 
                 Debug.Assert(timerIsNotDisposed, "ErrorCallback timer has been disposed");
 
@@ -799,7 +805,7 @@ private void ErrorCallback(object state)
             _waitHandles.ErrorEvent.Reset();
 
             // the error state is cleaned, destroy the timer to avoid periodic invocation
-            Timer t = _errorTimer;
+            ITimer t = _errorTimer;
             _errorTimer = null;
             if (t != null)
             {

src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/SqlExceptionHelper.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.Data.SqlClient.UnitTests.ConnectionPool
+{
+    /// <summary>
+    /// Test helper for creating <see cref="SqlException"/> instances. Since <see cref="SqlException"/> has
+    /// an internal constructor, instances must be created via the <see cref="SqlException.CreateException"/> factory method.
+    /// </summary>
+    internal static class SqlExceptionHelper
+    {
+        /// <summary>
+        /// Creates a <see cref="SqlException"/> with the specified message using the internal factory method.
+        /// </summary>
+        /// <param name="message">The error message for the exception.</param>
+        /// <returns>A new <see cref="SqlException"/> with the specified message.</returns>
+        internal static SqlException CreateSqlException(string message)
+        {
+            var collection = new SqlErrorCollection();
+            collection.Add(new SqlError(0, (byte)0, (byte)0, "TestServer", message, "", 0));
+            return SqlException.CreateException(collection, "");
+        }
+    }
+}