Doctests assume cabal-install

[mboes]

The doctests test suite fails when using Stack:

$ stack test
[...]
Test suite failure for package network-2.6.2.2
    doctest:  exited with: ExitFailure 1
Logs printed to console

This is because doctests.hs hardcodes a bunch of paths that are private to Cabal and private to where cabal-install decides to put the builddir etc.

We need a more generic way of running doctests so as to support running all test suites on all build tools users/developers commonly use.

[hvr]

fwiw, this also affects cabal new-build

$ dist-newstyle/build/network-2.6.2.2/build/doctest/doctest
doctest: doctest: can't find a package database at dist/package.conf.inplace

[eborden]

Yes, the new travis.yml is showing this: https://travis-ci.org/haskell/network/jobs/135456991

[hvr]

I've seen doctest-related issues to appear in a few places already with new-build.

[eborden]

Hmm, digging around a bit. This might just require a doctest upgrade for auto discovery. Will dig further, but Warp's doctest usage is quite simple:
yesodweb/wai@52f892c

[eborden]

Hmm, actually we are using the same version. @kazu-yamamoto do you have any specifics on the current doc test setup?

[hvr]

the problem for new-build is that doctest simply doesn't know about new-build's different package-db layout. See https://github.com/sol/doctest/blob/master/src/PackageDBs.hs

[kazu-yamamoto]

I close this in favor of #268.