Use GHC 8.3, not GHC 7. Not sure why 7 is enabled, let me try and disable it.

I got this error when running the tests.

TinyThreePassCompilerSpec.hs:1:53:
    Not in scope: `main'
    Perhaps you meant `min' (imported from Prelude)

I modified it, by adding

main :: IO ()
main = hspec spec

And then the basic test runs normally.
But when I want to attampt to the final tests. The same error occurs.