Could not find module ‘Test.HUnit’

Question

I have a fresh installation of stack and ghci:

$ stack --version

 Version 1.6.3, Git revision b27e629b8c4ce369e3b8273f04db193b060000db (5454 commits) x86_64 hpack-0.20.0 

$ ghci --version

 The Glorious Glasgow Haskell Compilation System, version 8.2.1 

I make a new project:

$ stack new so-mve

 Downloading template "new-template" to create project "so-mve" in so-mve/ ... blah blah blah ... Looking for .cabal or package.yaml files to use to init the project. Using cabal packages: - so-mve/ Selecting the best among 12 snapshots... * Matches lts-10.3 Selected resolver: lts-10.3 Initialising configuration using resolver: lts-10.3 Total number of user packages considered: 1 Writing configuration to file: so-mve/stack.yaml All done. 

Looks pretty good:

$ tree so-mve

 so-mve ├── ChangeLog.md ├── LICENSE ├── README.md ├── Setup.hs ├── app │   └── Main.hs ├── package.yaml ├── so-mve.cabal ├── src │   └── Lib.hs ├── stack.yaml └── test └── Spec.hs 

It builds and runs:

$ cd so-mve
$ stack build

 so-mve-0.1.0.0: build (lib + exe) Preprocessing library for so-mve-0.1.0.0.. Building library for so-mve-0.1.0.0.. Preprocessing executable 'so-mve-exe' for so-mve-0.1.0.0.. Building executable 'so-mve-exe' for so-mve-0.1.0.0.. so-mve-0.1.0.0: copy/register Installing library in /...blah-blah.../so-mve/.stack-work/install/x86_64-osx/lts-10.3/8.2.2/lib/x86_64-osx-ghc-8.2.2/so-mve-0.1.0.0-5kG2WnHWwo99IiYYGoxrcC Installing executable so-mve-exe in /...blah-blah.../so-mve/.stack-work/install/x86_64-osx/lts-10.3/8.2.2/bin Registering library for so-mve-0.1.0.0.. 

$ stack exec so-mve-exe

 someFunc 

Tests run:

$ stack test

 blah blah blah [2 of 2] Compiling Main ( test/Spec.hs, .stack-work/dist/x86_64-osx/Cabal-2.0.1.0/build/so-mve-test/so-mve-test-tmp/Main.o ) ...blah-blah-blah... Progress: 1/2Test suite not yet implemented so-mve-0.1.0.0: Test suite so-mve-test passed Completed 2 action(s). 

I triple check that HUnit is installed

$ stack install HUnit

 Populated index cache. 

I add one line to test/Spec.hs

$ cat test/Spec.hs

 import Test.HUnit main :: IO () main = putStrLn "Test suite not yet implemented" 

Doesn't work:

$ stack test

 so-mve-0.1.0.0: unregistering (components added: test:so-mve-test) so-mve-0.1.0.0: build (lib + exe + test) Preprocessing library for so-mve-0.1.0.0.. Building library for so-mve-0.1.0.0.. Preprocessing executable 'so-mve-exe' for so-mve-0.1.0.0.. Building executable 'so-mve-exe' for so-mve-0.1.0.0.. Preprocessing test suite 'so-mve-test' for so-mve-0.1.0.0.. Building test suite 'so-mve-test' for so-mve-0.1.0.0.. [2 of 2] Compiling Main ( test/Spec.hs, .stack-work/dist/x86_64-osx/Cabal-2.0.1.0/build/so-mve-test/so-mve-test-tmp/Main.o ) 

/...blah-blah.../so-mve/test/Spec.hs:1:1: error:
    Could not find module ‘Test.HUnit’
    Use -v to see a list of the files searched for.
  |          
1 | import Test.HUnit
  | ^^^^^^^^^^^^^^^^^

Progress: 1/2
--  While building custom Setup.hs for package so-mve-0.1.0.0 using:
      /Users/XXXXXXXX/.stack/setup-exe-cache/x86_64-osx/Cabal-simple_mPHDZzAJ_2.0.1.0_ghc-8.2.2 --builddir=.stack-work/dist/x86_64-osx/Cabal-2.0.1.0 build lib:so-mve exe:so-mve-exe test:so-mve-test --ghc-options " -ddump-hi -ddump-to-file -fdiagnostics-color=always"
    Process exited with code: ExitFailure 1

I don't have trouble importing other libraries, like Text.Read and Text.Printf . I googled around a bunch, but didn't find an answer. Any ideas for me?

Answer 1

You just need to add HUnit to the dependencies for your test project. When using stack , you should edit the package.yaml file to specify dependencies. In particular, your test configuration should look something like:

tests:
  so-mve-test:
    main:                Spec.hs
    source-dirs:         test
    ghc-options:
    - ...
    dependencies:
    - HUnit

This is documented in the latest Stack Guide , under the section Adding Dependencies .

Answer 2

You installed HUnit globally with stack , but that doesn't mean it is specified for your project .

Your cabal file for the project needs to specify a dependency on HUnit :

--so-mve.cabal
...
test-suite so-mve 
  type:                exitcode-stdio-1.0
  hs-source-dirs:      test
  main-is:             Spec.hs
  build-depends:       base
                     , HUnit
  ...

Text.Read and Text.Printf are both included in base , so you don't need to specify an additional dependency.

---

As pointed out in the comments, since you're using a package.yaml (as opposed to a stack.yaml ) configuration with the newer version of stack , you'll need to specify the dependency there instead of the .cabal file:

tests:
  so-mve-test:
    main: Spec.hs
    source-dirs: test
    ghc-options:
    - -threaded
    dependencies:
    - HUnit