Improve internal server connection management. (#1232)

Tests/MQTTnet.Core.Tests/BaseTestClass.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Tests.Mockups;
+
+namespace MQTTnet.Tests
+{
+    public abstract class BaseTestClass
+    {
+        public TestContext TestContext { get; set; }
+        
+        protected TestEnvironment CreateTestEnvironment()
+        {
+            return new TestEnvironment(TestContext);
+        }
+
+        protected Task LongDelay()
+        {
+            return Task.Delay(TimeSpan.FromSeconds(1));
+        }
+    }
+}