Could not find module ‘Test.Hspec.Discover’

I am a noob.

I have tried to copy and paste a single Hspec/QuickCheck test out of a bigger project into my own so I can tweak it and see how it behaves.

I have a structure like:

myproject/test/Spec.hs
myproject/test/mytest.hs

Copying from the other project my Spec.hs just has:

{-# OPTIONS_GHC -F -pgmF hspec-discover #-}

This is exactly the same as the example shown in the docs: http://hspec.github.io/hspec-discover.html

Additionally I have in my package.yml:

tests:
  myproject-test:
    main:                Spec.hs
    source-dirs:         test
    ghc-options:
    - -threaded
    - -rtsopts
    - -with-rtsopts=-N
    dependencies:
    - myproject
    - QuickCheck
    - hspec-megaparsec
    - hspec-discover

When I run stack test I get the following error:

$ stack test
hspec-discover  > configure
hspec-discover  > Configuring hspec-discover-2.6.1...
hspec-discover  > build
hspec-discover  > Preprocessing library for hspec-discover-2.6.1..
hspec-discover  > Building library for hspec-discover-2.6.1..
hspec-discover  > [1 of 4] Compiling Paths_hspec_discover
hspec-discover  > [2 of 4] Compiling Test.Hspec.Discover.Config
hspec-discover  > [3 of 4] Compiling Test.Hspec.Discover.Sort
hspec-discover  > [4 of 4] Compiling Test.Hspec.Discover.Run
hspec-discover  > Preprocessing executable 'hspec-discover' for hspec-discover-2.6.1..
hspec-discover  > Building executable 'hspec-discover' for hspec-discover-2.6.1..
hspec-discover  > [1 of 2] Compiling Main
hspec-discover  > [2 of 2] Compiling Paths_hspec_discover
hspec-discover  > Linking .stack-work/dist/x86_64-osx/Cabal-2.4.0.1/build/hspec-discover/hspec-discover ...
hspec-discover  > copy/register
hspec-discover  > Installing library in /Users/anentropic/.stack/snapshots/x86_64-osx/9ea21a5325b81a2dfa4286ce80451092e847f54dde50f04e1f7e952425f2d334/8.6.5/lib/x86_64-osx-ghc-8.6.5/hspec-discover-2.6.1-GcEMs7l4z3NWJQPD5eMXU
hspec-discover  > Installing executable hspec-discover in /Users/anentropic/.stack/snapshots/x86_64-osx/9ea21a5325b81a2dfa4286ce80451092e847f54dde50f04e1f7e952425f2d334/8.6.5/bin
hspec-discover  > Registering library for hspec-discover-2.6.1..
Building all executables for `myproject' once. After a successful build of all of them, only specified executables will be rebuilt.
myproject> configure (lib + exe + test)
Configuring myproject-0.1.0.0...
myproject> build (lib + exe + test)
Preprocessing library for myproject-0.1.0.0..
Building library for myproject-0.1.0.0..
[1 of 2] Compiling Lib
[2 of 2] Compiling Paths_waterloo_haskell
Preprocessing executable 'myproject-exe' for myproject-0.1.0.0..
Building executable 'myproject-exe' for myproject-0.1.0.0..
[1 of 2] Compiling Main
[2 of 2] Compiling Paths_waterloo_haskell
Linking .stack-work/dist/x86_64-osx/Cabal-2.4.0.1/build/myproject-exe/myproject-exe ...
Preprocessing test suite 'myproject-test' for myproject-0.1.0.0..
Building test suite 'myproject-test' for myproject-0.1.0.0..
[1 of 2] Compiling Main

/Users/anentropic/Documents/Dev/Personal/waterloo/myproject/test/Spec.hs:3:1: error:
    Could not find module ‘Test.Hspec.Discover’
    Perhaps you meant
      Test.Hspec.Discover.Run (from hspec-discover-2.6.1)
      Test.Hspec.Discover.Sort (from hspec-discover-2.6.1)
    Use -v to see a list of the files searched for.


--  While building package myproject-0.1.0.0 using:
      /Users/anentropic/.stack/setup-exe-cache/x86_64-osx/Cabal-simple_mPHDZzAJ_2.4.0.1_ghc-8.6.5 --builddir=.stack-work/dist/x86_64-osx/Cabal-2.4.0.1 build lib:myproject exe:myproject-exe test:myproject-test --ghc-options " -fdiagnostics-color=always"
    Process exited with code: ExitFailure 1
Progress 2/3

There's a lot I don't understand. But the main puzzle here is the output appears to show that hspec-discover-2.6.1 was successfully installed.

I have not written Test.Hspec.Discover anywhere in my bits of code so I have to assume the error comes from {-# OPTIONS_GHC -F -pgmF hspec-discover #-} (also the error message points to Spec.hs as the source).

Um, what am I doing wrong? hspec-discover can't find itself?

Doing a Hoogle search for that module name shows that it is in hspec, not hspec-discover. Please try adding a test suite dependency on hspec.