Fixed flaky test

Author: sakno

src/DotNext.Tests/Test.cs

@@ -45,4 +45,18 @@ private protected static ReadOnlySequence<T> ToReadOnlySequence<T>(ReadOnlyMemor
     private protected static Action<T> Same<T>(T expected)
         where T : class
         => actual => Same(expected, actual);
+    
+    protected static TResult SuspendContext<TResult>(Func<TResult> func)
+    {
+        var currentContext = SynchronizationContext.Current;
+        SynchronizationContext.SetSynchronizationContext(null);
+        try
+        {
+            return func();
+        }
+        finally
+        {
+            SynchronizationContext.SetSynchronizationContext(currentContext);
+        }
+    }
 }

src/DotNext.Tests/Threading/Leases/LeaseTests.cs

@@ -132,7 +132,7 @@ public static async Task WorkerProtectedWithLease()
         await using var consumer = new TestLeaseConsumer(provider);
         True(await consumer.TryAcquireAsync());
 
-        var result = await consumer.ExecuteAsync(Worker);
+        var result = await SuspendContext(() => consumer.ExecuteAsync(Worker));
         Equal(42, result);
 
         static async Task<int> Worker(CancellationToken token)