I wonder why you call the expression in SELECT clause "test clause". SQL WHERE clause is destined for filtering, which seems closer to the term you used.
In Oracle SQL, you may only use expressions in SELECT clause. You are passing the comparison condition there.
Both these language elements are described in SQL Language Reference Guide, which is available with other Oracle documentation e.g. online on http://tahiti.oracle.com/
Please consult the one for your Oracle version.
Without knowing, how is the query supposed to process, it is impossible to propose anything.
And no, BOOLEAN data type (or any enumeration one holding values true and false) is not available in Oracle SQL.