A countdown to simulated failure.
Defined in header
Throw an exception on the Nth failure.
Set an error code on the Nth failure.
Construct a counter.
On the Nth operation, the class will fail with the specified error code,
or the default error code of
test::test_failure. Instances of this
class may be used to build objects which are specifically designed to aid
in writing unit tests, for interfaces which can throw exceptions or return
error_code values representing