Loading a file under test-suite fails when importing library

[mjhoy]

Loading a file in a cabal project's test suite that links to a library defined in the project with inferior-haskell-load-file (C-c C-l) fails.

For example. Given a project layout such as:

src/Foo/Bar.hs
foo.cabal
test.hs

foo.cabal

name:                  foo
-- ...
library
  -- ...
  hs-source-dirs:      src
  exposed-modules:     Foo.Bar

test-suite test-foo
  type: exitcode-stdio-1.0
  main-is: test.hs
  build-depends:       base >=4.9 && <4.10,
                       foo

test.hs:

module Main where

import Foo.Bar

main :: IO ()
main = -- ...

Running C-c C-l from test.hs fails with:

test.hs:3:1: error:
    Failed to load interface for ‘Foo.Bar’
    Use -v to see a list of the files searched for.
Failed, modules loaded: none.

The proper way to load a file in the test suite with cabal is to run cabal repl <test target>; in this case cabal repl test-foo, which will work correctly. See the comment here: haskell/cabal#2032 (comment)

I can get around this by C-u M-x inferior-haskell-start-process cabal repl test-foo. Once you figure that out, it's not so difficult, but I wonder if there could be more intelligent loading of test files?

[mjhoy]

I should clarify I am using "cabal repl" as haskell-program-name.