private async Task <string> CreatePackageWithTargetFrameworkInternal(string nuspecFileFullPath, string frameworkVersion)
{
string nuspecDir = Path.GetDirectoryName(nuspecFileFullPath);
AddContent(nuspecDir, frameworkVersion);
AddLib(nuspecDir, frameworkVersion);
var arguments = string.Join(string.Empty, CommandlineHelper.PackCommandString, @"""" + nuspecFileFullPath + @"""", CommandlineHelper.OutputDirectorySwitchString, @"""" + nuspecDir + @"""");
var commandlineHelper = new CommandlineHelper(TestOutputHelper);
await commandlineHelper.InvokeNugetProcess(arguments, Path.GetFullPath(Path.GetDirectoryName(nuspecFileFullPath)));
string[] nupkgFiles = Directory.GetFiles(nuspecDir, "*.nupkg").ToArray();
return(nupkgFiles.Length == 0 ? null : nupkgFiles[0]);
}