The preconditions for tests 15.12.2-0-3 and 15.12.3-0-3 do not return true
description
The preconditions for tests 15.12.2-0-3 and 15.12.3-0-3 both return a function and not a boolean.
For example, in test 15.12.2-0-3 the precondition is: "return JSON && Object.getOwnPropertyDescriptor". getOwnPropertyDescriptor is a function and therefore the whole expression returns a function. Since the test driver expects "true" the precondition fails. I believe that in this case the problem is that "fnExists" is missing and the precondition should be "return JSON && fnExists(Object.getOwnPropertyDescriptor)".