Fixed wrong application domain selected (#410)

This change fixed the FileNotFoundException at SqlDependency.Start() by replacing the default AppDomain with the current.

Author: DavidEshtehari

src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/Interop/SNINativeMethodWrapper.cs

@@ -80,10 +80,7 @@ internal static int SniMaxComposedSpnLength
 
         static AppDomain GetDefaultAppDomainInternal()
         {
-            var host = new mscoree.CorRuntimeHost();
-            host.GetDefaultDomain(out object temp);
-            AppDomain defaultAppDomain = temp as AppDomain;
-            return defaultAppDomain;
+            return AppDomain.CurrentDomain;
         }
 
         internal static _AppDomain GetDefaultAppDomain()

src/Microsoft.Data.SqlClient/tests/ManualTests/Microsoft.Data.SqlClient.ManualTesting.Tests.csproj

@@ -121,6 +121,7 @@
     <Compile Include="SQL\SqlBulkCopyTest\CopyWidenNullInexactNumerics.cs" />
     <Compile Include="SQL\SqlCommand\SqlCommandSetTest.cs" />
     <Compile Include="SQL\SqlCredentialTest\SqlCredentialTest.cs" />
+    <Compile Include="SQL\SqlDependencyTest\SqlDependencyTest.cs" />
     <Compile Include="SQL\SqlSchemaInfoTest\SqlSchemaInfoTest.cs" />
     <Compile Include="SQL\SqlStatisticsTest\SqlStatisticsTest.cs" />
     <Compile Include="SQL\SqlBulkCopyTest\AdjustPrecScaleForBulkCopy.cs" />

src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/SqlDependencyTest/SqlDependencyTest.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using Xunit;
+
+namespace Microsoft.Data.SqlClient.ManualTesting.Tests
+{
+    public class SqlDependencyTest
+    {
+        [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup), nameof(DataTestUtility.IsNotAzureServer))]
+        public void SqlDependencyStartStopTest()
+        {
+            try
+            {
+                SqlDependency.Start(DataTestUtility.TCPConnectionString);
+                SqlDependency.Stop(DataTestUtility.TCPConnectionString);
+            }
+            catch (Exception e)
+            {
+                Assert.True(false, e.Message);
+            }
+        }
+    }
+}