Specify build and probe tables to hash join?
When you hint a query like that, you force the join order -- you've actually answered your own question. 

If you want to test join types and still leave the optimizer with room to explore things, use query options, like this:

SELECT *
FROM HumanResources.Employee e
INNER JOIN HumanResources.EmployeeDepartmentHistory edh 
ON e.BusinessEntityID = edh.BusinessEntityID
INNER JOIN HumanResources.Shift s 
ON edh.ShiftID = s.ShiftID
OPTION(MERGE JOIN, HASH JOIN);