diff --git a/src/SystemTests/XApiClientTestBase.cs b/src/SystemTests/XApiClientTestBase.cs
index 8f8afdd..8695444 100644
--- a/src/SystemTests/XApiClientTestBase.cs
+++ b/src/SystemTests/XApiClientTestBase.cs
@@ -42,13 +42,13 @@ public string? MessageFolder
             _messageFolder = value;
             if (value == null)
             {
-                Client.ApiConnector.MessageReceived -= Connector_MessageReceived;
-                Client.ApiConnector.MessageSent -= Connector_MessageSent;
+                Client.ApiConnector.Connector.MessageReceived -= Connector_MessageReceived;
+                Client.ApiConnector.Connector.MessageSent -= Connector_MessageSent;
             }
             else
             {
-                Client.ApiConnector.MessageReceived += Connector_MessageReceived;
-                Client.ApiConnector.MessageSent += Connector_MessageSent;
+                Client.ApiConnector.Connector.MessageReceived += Connector_MessageReceived;
+                Client.ApiConnector.Connector.MessageSent += Connector_MessageSent;
             }
         }
     }
diff --git a/src/UnitTests/XApiClientTest.cs b/src/UnitTests/XApiClientTest.cs
index 44650f1..2e8e777 100644
--- a/src/UnitTests/XApiClientTest.cs
+++ b/src/UnitTests/XApiClientTest.cs
@@ -1,15 +1,44 @@
+using NSubstitute;
+using System.Diagnostics;
+
 namespace Xtb.XApi.UnitTests;
 
 public class XApiClientTest
 {
+    private IClient _requestingConnector;
+    private IClient _streamingConnector;
+    private IXApiClient _xclient;
+
+    public XApiClientTest()
+    {
+        _requestingConnector = Substitute.For<IClient>();
+        _streamingConnector = Substitute.For<IClient>();
+        _xclient = new XApiClient(new ApiConnector(_requestingConnector, new StreamingApiConnector(_streamingConnector)));
+    }
+
     [Fact]
     public void Create()
     {
-        var client = XApiClient.Create("81.2.190.163", 5112, 5113);
+        var xclient = XApiClient.Create("81.2.190.163", 5112, 5113);
+
+        Assert.NotNull(xclient.ApiConnector);
+        Assert.NotNull(xclient.ApiConnector.Endpoint);
+        Assert.Equal("81.2.190.163", xclient.ApiConnector.Endpoint.Address.ToString());
+        Assert.Null(xclient.AccountId);
+    }
+
+    [Fact]
+    public void SendCommandsWithDelay()
+    {
+        _requestingConnector.SendMessageWaitResponse(Arg.Any<string>()).Returns("{}");
+
+        var stopwatch = Stopwatch.StartNew();
+
+        _xclient.GetSymbol("US500");
+        _xclient.GetSymbol("US500");
+
+        stopwatch.Stop();
+        Assert.True(stopwatch.Elapsed.TotalMilliseconds > 400);
 
-        Assert.NotNull(client.ApiConnector);
-        Assert.NotNull(client.ApiConnector.Endpoint);
-        Assert.Equal("81.2.190.163", client.ApiConnector.Endpoint.Address.ToString());
-        Assert.Null(client.AccountId);
     }
 }
\ No newline at end of file