http://stackoverflow.com/questions/20651892/tests-pass-in-ghci-but-fail-in-cabal-test

Main.hs

module Main
       where

main = undefined

rose.cabal

name: rose
version: 0.1
cabal-version: >= 1.10
build-type: Simple

executable one
  main-is:             Main.hs
  build-depends:       base
  default-language:    Haskell2010
  ghc-options:       -Wall

Test-Suite test-one
  type:              exitcode-stdio-1.0
  main-is:           Tests.hs
  build-depends:     base, HUnit
  default-language:  Haskell2010
  ghc-options:       -Wall

Tests.hs

module Main (
    main
) where

import Test.HUnit
import Data.Char

four :: Int
four = 4

tests, test1, test2, test3 :: Test
test1 = TestCase $ assertEqual "test upCase" "FOO" (map toUpper "foo")
test2 = TestCase $ assertEqual "testing that the result is 4" 4 (4::Int)
test3 = TestCase $ assertEqual "testing that 4 is 4" four 4

tests = TestList [TestLabel "test1" test1, TestLabel "test2" test2, TestLabel "test3" test3]

main :: IO ()
main = do _ <- runTestTT $ tests
          return ()

Note that you need to manually set a failing exit code when tests fail for Cabal to know (otherwise, cabal test would assume that everything passed), like so:

import qualified System.Exit as Exit

main = do
    count <- HUnit.runTestTT tests
    if HUnit.failures count > 0 then Exit.exitFailure else return ()