Functional tests rely on stack and don't seem to work with new-build

[michaelpj]

After adding stack to the shell.nix dependencies and hie to the build-tool-depends I get:

Test suite func-test: RUNNING...
Warming up HIE cache...
func-test: fd:45: hGetLine: end of file
func-test: Language server unexpectedly terminated
Test suite func-test: FAIL

[lukel97]

I did a bit of debugging on this last night: the hie instance invoked by cabal new-test :func-test isn’t able to find cabal-helper-wrapper. Oddly enough cabal new-run :func-test is.
The solution was to add cabal-helper:cabal-helper-wrapper to build-tool-depends for func-test, but then I ran into this issue with cabal haskell/cabal#6011

[jneira]

hie does not longer use cabal-helper-wrapper and we are gonna to run the test suite with cabal v2-test soon in azure ci: #1571