These testcases are intended to provoke HDLMake
Errors, therefore not generating a synthesis Makefile.

Before making the Makefile write 'atomic' with
contextmanager, these Makefiles have been generated both
on Linux and Windows.
On Linux, the testsuite passed even then.
But on Windows, these Makefiles have been reported
as busy while the TestCase tried to delete the files.
This resulted in OsErrors.