Get all nuget packages in solution

I'm trying to write a unit test to enforce consolidation of Nuget packages (we have a build requirement that all unit tests pass so this would keep PRs that aren't consolidating from passing) and I was attempting to use Nuget.Core to do that. However, I cannot seem to find my way through their libraries and no one has asked this question yet. So, how can I get all the Nuget packages a given solution references programmatically?