title: How to limit SOQL results to those accessible to a user
body: <p>I have admin API access for my organization. I'd like to run the same SOQL query, but get back results as visible to various users in my org: running "SELECT Name FROM Account" for user A, should only return account names accessible to user A.</p>
  
  <p>I know this is easy if each user provides my application with their password and security token, so I can log in as them and run the query, but I want to do this only using my admin account.</p>
  
  <p>this is very similar to:</p>
  
  <p><a href="https://stackoverflow.com/q/10102815">Salesforce: impersonation using the API</a></p>
  
  <p>but in this case I do have access to the data, I just want to filter it as though the request came from a specific user. It looks like there's an Apex "unit testing" method called System.RunAs() which looks close, but I want to run this via REST.</p>