Detect and run tests in sandbox if present
Detect and run tests in sandbox if present

Instead of assuming a global install, use the sandbox to run tests when
available. Mimics behaviour of cabal install.

Signed-off-by: Rohan Jain <1d6e1cf70ec6f9ab28d3ea4b27a49a77654d370e@rohanjain.in>

crodjer/haste-compiler,szatkus/haste-compiler,akru/haste-compiler,crodjer/haste-compiler,jtojnar/haste-compiler,beni55/haste-compiler,akru/haste-compiler,kranich/haste-compiler,santolucito/haste-compiler,szatkus/haste-compiler,santolucito/haste-compiler,szatkus/haste-compiler,crodjer/haste-compiler,crodjer/haste-compiler,santolucito/haste-compiler,joelburget/haste-compiler,szatkus/haste-compiler,akru/haste-compiler,santolucito/haste-compiler,jtojnar/haste-compiler,joelburget/haste-compiler,jtojnar/haste-compiler,kranich/haste-compiler,akru/haste-compiler,beni55/haste-compiler,joelburget/haste-compiler,akru/haste-compiler,beni55/haste-compiler,jtojnar/haste-compiler,kranich/haste-compiler,nyson/haste-compiler,nyson/haste-compiler,nyson/haste-compiler,nyson/haste-compiler,kranich/haste-compiler,crodjer/haste-compiler,joelburget/haste-compiler,beni55/haste-compiler