fixes#21353
```nim
result = newNodeIT(nkTupleConstr, info, t)
result.add(newNodeIT(nkNilLit, info, t))
result.add(newNodeIT(nkNilLit, info, t))
```
The old implementation uses `t` which is the type of the closure
function as its type. It is not correct and generates ((nil, nil), (nil,
nil)) for `default(closures)`. This PR creates `(tyPointer, tyPointer)`
for fake closure types just like what cctypes do.
Each test must have a filename of the form: t*.nim
Note:Testament is only aware of tests under a directory (eg tests/foo/) and will ignore
top-level tests like tests/tbar.nim.
Specs
Each test can contain a spec in a discard """ ... """ block.
Check out the parseSpec procedure in the specs module for a full and reliable reference
action
Specifies what action this test should take.
Default: run
Options:
compile - compiles the module and fails the test if compilations fails.
run - compiles and runs the module, fails the test if compilation or
execution of test code fails.
reject - compiles the module and fails the test if compilation succeeds.
There are certain spec keys that imply run, including output and
outputsub.
Categories
Each folder under this directory represents a test category, which can be
tested by running koch tests pcat <category> (or cat to avoid parallel
testing, which is slower).
The folder dll contains simple DLL tests.
The folder realtimeGC contains a test for validating that the realtime GC
can run properly without linking against the nimrtl.dll/so.