throw exception when there are no any configured tarantool nodes (#134)

* throw exception when there are no any configured tarantool nodes

Author: nazaroid

src/progaudi.tarantool/ClientSetupException.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace ProGaudi.Tarantool.Client
+{
+    public class ClientSetupException : Exception {
+        public ClientSetupException(string msg) : base(msg)
+        {
+            
+        }
+    }
+}

src/progaudi.tarantool/LogicalConnection.cs

@@ -127,6 +127,9 @@ public async Task<byte[]> SendRawRequest<TRequest>(TRequest request, TimeSpan? t
 
         private async Task LoginIfNotGuest(GreetingsResponse greetings)
         {
+            if (! _clientOptions.ConnectionOptions.Nodes.Any()) 
+                throw new ClientSetupException("There are zero configured nodes, you should provide one");
+
             var singleNode = _clientOptions.ConnectionOptions.Nodes.Single();
 
             if (string.IsNullOrEmpty(singleNode.Uri.UserName))
@@ -204,4 +207,4 @@ private ArraySegment<byte> CreateAndSerializeHeader<TRequest>(
             return new ArraySegment<byte>(packetSizeBuffer, 0, lengthAndHeaderLengthByteCount);
         }
     }
-}
+}

src/progaudi.tarantool/NetworkStreamPhysicalConnection.cs

@@ -36,6 +36,9 @@ public void Dispose()
 
         public async Task Connect(ClientOptions options)
         {
+            if (! options.ConnectionOptions.Nodes.Any()) 
+                throw new ClientSetupException("There are zero configured nodes, you should provide one");
+
             options.LogWriter?.WriteLine("Starting socket connection...");
             var singleNode = options.ConnectionOptions.Nodes.Single();
 
@@ -121,4 +124,4 @@ private void CheckConnectionStatus()
             }
         }
     }
-}
+}

tests/progaudi.tarantool.tests/Box/Options.cs

@@ -50,5 +50,15 @@ public async Task ReadBoxInfoOnConnectDisabled()
                 box.Info.ShouldBeNull();
             }
         }
+
+        [Fact]
+        public async Task ShouldThrowIfThereAreNoNodesWereConfigured()
+        {
+            var options = new ClientOptions();
+            using (var box = new Client.Box(options))
+            {
+                await Assert.ThrowsAsync<ClientSetupException>(() => box.Connect());
+            }
+        }
     }
 }