#2708 add Add a judgment to the graph constructor (#2709)

* #2708 add Add a judgment to the graph constructor

* #2708 add Add a judgment to the graph constructor & added unit test

* #2708 #2079 move GraphTests to AutoGen.Tests; delete AutoGen.Core.Tests project

dotnet/test/AutoGen.Tests/GroupChat/GraphTests.cs

@@ -0,0 +1,18 @@
+
+using Xunit;
+
+namespace AutoGen.Tests
+{
+    public class GraphTests
+    {
+        [Fact]
+        public void GraphTest()
+        {
+            var graph1 = new Graph();
+            Assert.NotNull(graph1);
+
+            var graph2 = new Graph(null);
+            Assert.NotNull(graph2);
+        }
+    }
+}