Bump test projects up to .NET 4.5.2

- aspnet/Testing#248
- xUnit no longer supports .NET 4.5.1
- build tests for desktop .NET only on Windows

Author: dougbu

test/Microsoft.Data.Sqlite.Tests/Microsoft.Data.Sqlite.Tests.csproj

@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <Import Project="..\..\build\common.props" />
   <PropertyGroup>
-    <TargetFrameworks>net451;netcoreapp1.1</TargetFrameworks>
+    <TargetFrameworks>net452;netcoreapp1.1</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">netcoreapp1.1</TargetFrameworks>
     <RuntimeIdentifier Condition="'$(TargetFramework)' != 'netcoreapp1.1'">win7-x64</RuntimeIdentifier>
   </PropertyGroup>
   <ItemGroup>
@@ -12,7 +13,7 @@
     <PackageReference Include="xunit" Version="2.2.0-*" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0-*" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetFramework)' == 'net451'">
+  <ItemGroup Condition="'$(TargetFramework)' == 'net452'">
     <PackageReference Include="System.AppContext" Version="4.4.0-*" />
   </ItemGroup>
 </Project>

test/Microsoft.Data.Sqlite.Tests/NativeLibraryLoaderTest.net451.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-#if NET451
+#if NET452
 using System;
 using System.IO;
 using System.Reflection;

test/Microsoft.Data.Sqlite.Tests/SqliteConnectionTest.cs

@@ -13,7 +13,7 @@ namespace Microsoft.Data.Sqlite
 {
     public class SqliteConnectionTest
     {
-#if NET451
+#if NET452
         private static readonly string BaseDirectory = AppDomain.CurrentDomain.BaseDirectory;
 #else
         private static readonly string BaseDirectory = AppContext.BaseDirectory;

test/Microsoft.Data.Sqlite.Tests/SqliteDataReaderTest.cs

@@ -634,7 +634,7 @@ public void IsClosed_returns_true_when_closed()
                 connection.Open();
 
                 var reader = connection.ExecuteReader("SELECT 1;");
-#if NET451
+#if NET452
                 reader.Close();
 #else
                 ((IDisposable)reader).Dispose();