private IEnumerable <MissingPackageDependency> GetMissingPackages(FrameworkName targetFramework)
{
// All dependencies of all packages ...
return(Packages.SelectMany(p => p.GetCompatiblePackageDependencies(targetFramework),
(package, dependency) => new { package, dependency })
// ... that aren't installed as a package ...
.Where(d => !Packages.Select(p => p.Id).Contains(d.dependency.Id))
// ... or as a project
.Where(d => !MsBuildProject.GetProjectReferenceNames().Contains(d.dependency.Id))
// Dependencies don't have good equality checking
.GroupBy(d => d.dependency.ToString())
.Select(g => new MissingPackageDependency(g.First().dependency, g.Select(d => d.package))));
}