cabal-doctest

A Setup.hs helper for running doctests.

Example Usage

See [https://github.com/phadej/cabal-doctest/tree/master/example] for an example package. (Note that the example requires Cabal-1.24 or later, but you can relax this bound safely, although running doctests won’t be supported on versions of Cabal older than 1.24.)

To use this library in your Setup.hs, you should specify a custom-setup section in your .cabal file. For example:

custom-setup
 setup-depends:
   base >= 4 && <5,
   Cabal,
   cabal-doctest >= 1 && <1.1

/Note:/ Cabal dependency is needed because of Cabal/GH-4288 bug.

You’ll also need to specify build-type: Custom at the top of the .cabal file. Now put this into your Setup.hs file:

module Main where

import Distribution.Extra.Doctest (defaultMainWithDoctests)

main :: IO ()
main = defaultMainWithDoctests "doctests"

When you build your project, this Setup will generate a Build_doctests module. To use it in a testsuite, simply do this:

module Main where

import Build_doctests (flags, pkgs, module_sources)
import Data.Foldable (traverse_)
import Test.DocTest (doctest)

main :: IO ()
main = do
    traverse_ putStrLn args -- optionally print arguments
    doctest args
  where
    args = flags ++ pkgs ++ module_sources

Additional configuration

The cabal-doctest based Setup.hs supports few extensions fields in pkg.cabal files to customise the doctest runner behaviour, without customising the default doctest.hs.

test-suite doctests:
  if impl(ghc >= 8.0)
    x-doctest-options: -fdiagnostics-color=never
  x-doctest-source-dirs: test
  x-doctest-modules: Servant.Utils.LinksSpec

  ...

• x-doctest-options Additional arguments passed into doctest command.
• x-doctest-modules Additional modules to doctest. May be useful if you have doctest in test or executables (i.e not default library complonent).
• x-doctest-src-dirs Additional source directories to look for the modules.

Notes

• custom-setup section is supported starting from cabal-install-1.24. For older cabal-install's you have to install custom setup dependencies manually.

• stack respects custom-setup starting from version 1.3.3. Before that you have to use explicit-setup-deps setting in your stack.yaml. (stack/GH-2094)

• There is an issue in the Cabal issue tracker about adding cabal doctest command. After that command is implemented, this library will be deprecated.

• If your library contains cbits, you might need to depend on the library itself in doctests test-suite. We aren’t sure whether this a bug or not. See #5 issue for longer explanation.

• You can use x-doctest-options field in test-suite doctests to pass additional flags to the doctest.

• For build-type: Configure packages, you can use defaultMainAutoconfWithDoctests function to make custom Setup.hs script.

• If you use the default . in hs-source-dirs, then running doctests might fail with weird errors (ambigious module errors). Workaround is to move sources under src/ or some non-top-level directory.

Copyright

Copyright 2017 Oleg Grenrus.

Available under the BSD 3-clause license.