tfdleak: fix flakyness on Windows (#14550)

* tfdleak_multiple: introduce stress tester for tfdleak

Imported from #14548 and tweaked for consumption by testament.

This test seems to be really good at bringing out the flakyness of
tfdleadk.

Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>

* tfdleak: increase accuracy of the test on Windows

This commit implements a new testing strategy for Windows:
1. We duplicate the handle that will be tested and enable inheritance.
   This duplicate will serve as a reference handle.
2. In addition to checking whether the handle is valid, we also verify
   whether the handle is the same as the reference. This gives us
   complete certainty on whether the handle in question is inherited
   from the parent.
   A side effect is that this uses Windows 10+ APIs. But since
   this is just for the test, we don't have to be picky about it.

Ideally we would want to do something like this for other POSIX-based
system, but most of them lack a facility to do this, and as of writing
there isn't any false positive for them, so we won't need the additional
checks.

MemFile.fHandle will also no longer be tested, as this handle defaults
to being invalid.

Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>

0 files changed, 0 insertions, 0 deletions