A cabal-dev workflow

sample.cabal

name:                sample
version:             0.1.0.0
-- synopsis:            
-- description:
-- homepage:            
-- license:             
-- license-file:        
-- author:              
-- maintainer:          
-- copyright:           
-- category:            
stability:           experimental
build-type:          Simple
cabal-version:       >=1.8

-- This is where the magic happens
flag developer
  description: operate in developer mode
  default: False

-- Your usual test suite
test-suite tests
  type:               exitcode-stdio-1.0
  main-is:            tests/Main.hs
  hs-source-dirs:     tests
  other-modules:      Test.Test
  build-depends:      sample, base
                      test-framework >= 0.2.0,
                      test-framework-quickcheck2 >= 0.2.0, QuickCheck >= 2,
                      test-framework-hunit >= 0.2.0, HUnit >= 1.2 && < 2

library
  exposed-modules:  Data.YourModule
  hs-source-dirs:   src
  build-depends:    base

  if flag(developer)
    hs-source-dirs: tests
    other-modules:  Test.Test
    build-depends:  test-framework >= 0.2.0,
                    test-framework-quickcheck2 >= 0.2.0, QuickCheck >= 2,
                    test-framework-hunit >= 0.2.0, HUnit >= 1.2 && < 2

workflow.md

cabal-dev configure --flags=developer
cabal-dev build
cabal-dev ghci

> import Test.Test
> runTests