Fixing nuget API calls and fixing the nuget test package directory creation, so that nuget can restore using it.

build/Microsoft.DotNet.Cli.Test.targets

@@ -70,6 +70,8 @@
       <TestDirectory>$(RepoRoot)/test/</TestDirectory>
       <DotnetUnderTest>$(Stage2Directory)</DotnetUnderTest>
     </PropertyGroup>
+
+    <MakeDir Directories="$(TestPackagesDir)" Condition="!Exists('$(TestPackagesDir)')"/>
   </Target>
 
   <Target Name="BuildTests"
@@ -213,9 +215,10 @@
       <DotNetPackMsbuildArgs Condition=" '$(IsDesktopAvailable)' == 'True' And '%(TestPackageProject.PackRuntime)' != '' ">/p:RuntimeIdentifier=%(TestPackageProject.PackRuntime)</DotNetPackMsbuildArgs>
     </PropertyGroup>
 
-    <DotNetRestore ToolPath="$(Stage2Directory)"
+    <DotNetRestore ToolPath="$(Stage0Directory)"
                    Source="$(TestPackagesDir)"
-                   WorkingDirectory="%(TestPackageProject.FullPath)" />
+                   ConfigFile="$(RepoRoot)\NuGet.Config"
+                   ProjectPath="%(TestPackageProject.ProjectPath)" />
 
     <DotNetBuild Framework="%(TestPackageProject.Framework)"
                  Runtime="%(TestPackageProject.Runtime)"

build_projects/dotnet-cli-build/DotNetRestore.cs

@@ -12,9 +12,11 @@ namespace Microsoft.DotNet.Cli.Build
 
         protected override string Args
         {
-            get { return $"{GetProjectPath()} {GetSource()} {GetPackages()} {GetSkipInvalidConfigurations()} {GetRuntime()} {GetAdditionalParameters()}"; }
+            get { return $"{GetProjectPath()} {GetConfigFile()} {GetSource()} {GetPackages()} {GetSkipInvalidConfigurations()} {GetRuntime()} {GetAdditionalParameters()}"; }
         }
 
+        public string ConfigFile { get; set; }
+
         public string AdditionalParameters { get; set; }
 
         public string ProjectPath { get; set; }
@@ -27,6 +29,16 @@ namespace Microsoft.DotNet.Cli.Build
         
         public string Runtime { get; set; }
 
+        private string GetConfigFile()
+        {
+            if (!string.IsNullOrEmpty(ConfigFile))
+            {
+                return $"--configfile {ConfigFile}";
+            }
+
+            return null;
+        }
+
         private string GetSource()
         {
             if (!string.IsNullOrEmpty(Source))

src/Microsoft.DotNet.Cli.Utils/CommandResolution/DepsJsonBuilder.cs

@@ -21,7 +21,7 @@ namespace Microsoft.DotNet.Cli.Utils
         public DepsJsonBuilder()
         {
             // This resolver is only used for building file names, so that base path is not required.
-            _versionFolderPathResolver = new VersionFolderPathResolver(path: null);
+            _versionFolderPathResolver = new VersionFolderPathResolver(rootPath: null);
         }
 
         public DependencyContext Build(

src/Microsoft.DotNet.ProjectJsonMigration/Microsoft.DotNet.Internal.ProjectModel/Resolution/PackageDependencyProvider.cs

@@ -28,7 +28,7 @@ namespace Microsoft.DotNet.Internal.ProjectModel.Resolution
                 _packagePathResolver = new FallbackPackagePathResolver(nugetPathContext);
 
                 // This resolver is only used for building file names, so that base path is not required.
-                _versionFolderPathResolver = new VersionFolderPathResolver(path: null);
+                _versionFolderPathResolver = new VersionFolderPathResolver(rootPath: null);
             }
 
             _frameworkReferenceResolver = frameworkReferenceResolver;