project with test-only package fails both build and test

[PierreVDL]

I would like to move my organization to stack.
In my first experiments, I noticed a behaviour that is according to me a bug.
Our projects have tests localized in separate packages:
among other to prevent test dependencies end up as development dependencies.
One can argue whether or not this is a good pattern,
but I can't change it just to get stack accepted.

On Microsoft Windows [Version 6.1.7601]
with stack [Version 1.3.0, Git revision 99b910d x86_64 hpack-0.15.0]
my multi-package project with a test-only package fails to build and to execute the test suite.

Steps to reproduce

The following multi-package project
Multiple.zip
yields for stack build

test-0.1.0.0: configure
src-0.1.0.0: build (lib)
src-0.1.0.0: copy/register
app-0.1.0.0: build (exe)
test-0.1.0.0: build
app-0.1.0.0: copy/register
Completed 3 action(s).
Log files have been written to: C:\multiple\.stack-work\logs\

--  While building package test-0.1.0.0 using:
      C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_Z6RU0evB_1.24.0.0_ghc-8.0.1.exe --builddir=.stack-work\dist\b7fec021 build --ghc-options " -ddump-hi -ddump-to-file"
    Process exited with code: ExitFailure 1
    Logs have been written to: C:\multiple\.stack-work\logs\test-0.1.0.0.log

    Configuring test-0.1.0.0...
    Cabal-simple_Z6RU0evB_1.24.0.0_ghc-8.0.1.exe: No libraries, executables,
    tests, or benchmarks are enabled for package test-0.1.0.0.

This behaviour surprises me, since

1. test.cabal specifies a test-suite, so tests should be enabled for package test-0.1.0.0.
2. Test suite are irrelevant for a build, so build should not fail when only tests (and benchmarks) are available.

And for 'stack test'

test-0.1.0.0: configure (test)
test-0.1.0.0: build (test)
test-0.1.0.0: copy/register
Log files have been written to: C:\multiple\.stack-work\logs\
Progress: 1/2'cabal copy' failed.  Error message:

--  While building package test-0.1.0.0 using:
      C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_Z6RU0evB_1.24.0.0_ghc-8.0.1.exe --builddir=.stack-work\dist\b7fec021 copy
    Process exited with code: ExitFailure 1
    Logs have been written to: C:\multiple\.stack-work\logs\test-0.1.0.0.log

    Configuring test-0.1.0.0...
    Preprocessing test suite 'test-test' for test-0.1.0.0...
    Cabal-simple_Z6RU0evB_1.24.0.0_ghc-8.0.1.exe: No executables and no library
    found. Nothing to do.

One possible cause of this issue is:
* No module named "Main". The 'main-is' source file should usually have a header indicating that it's a 'Main' module.

I agree that test-0.1.0.0 contains no executables and no library: yet a test-suite is present that should be executed!

Note: by out commenting line 41 '- test' of stack.yaml 'stack build' and 'stack test' works perfectly.

Method of installation

• Official binary, downloaded from stackage.org

[begriffs]

This just happened to me as well. Got the No module named "Main". error on Stack 1.2.0 for a project which has only a test-suite section, no executable or library. I upgraded to Stack 1.3.2 and get the same error.

[mgsloan]

I've pushed a fix! It now skips the cabal copy step if there's no lib or exes.

[PierreVDL]

Bug fix confirmed with stack 1.4 !
Thanks for the fix!

[PierreVDL]

Just noticed the problem reappeared in stack 1.4.0

C:\multiple>stack --version
Version 1.4.0, Git revision e714f1dd3fade19496d91bd6a017e435a96a6bcd x86_64 hpack-0.17.0

C:\multiple>stack build
Downloaded lts-7.14 build plan.
[1 of 2] Compiling Main             ( C:\sr\setup-exe-src\setup-Z6RU0evB.hs, C:\sr\setup-exe
-src\setup-Z6RU0evB.o )
[2 of 2] Compiling StackSetupShim   ( C:\sr\setup-exe-src\setup-shim-Z6RU0evB.hs, C:\sr\setu
p-exe-src\setup-shim-Z6RU0evB.o )
Linking C:\sr\setup-exe-cache\x86_64-windows\tmp-Cabal-simple_Z6RU0evB_1.24.2.0_ghc-8.0.1.ex
e ...
test-0.1.0.0: configure
test-0.1.0.0: build
src-0.1.0.0: configure (lib)
src-0.1.0.0: build (lib)
src-0.1.0.0: copy/register
Log files have been written to: C:\multiple\.stack-work\logs\
Progress: 2/3
--  While building package test-0.1.0.0 using:
      C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_Z6RU0evB_1.24.2.0_ghc-8.0.1.exe --builddir=.stack-work\dist\ca59d0ab build --ghc-options " -ddump-hi -ddump-to-file"
    Process exited with code: ExitFailure 1
    Logs have been written to: C:\multiple\.stack-work\logs\test-0.1.0.0.log

    Configuring test-0.1.0.0...
    Cabal-simple_Z6RU0evB_1.24.2.0_ghc-8.0.1.exe: No libraries, executables,
    tests, or benchmarks are enabled for package test-0.1.0.0.

[Topsii]

This happens for me too.
I also have windows:

stack --version
Version 1.4.0, Git revision e714f1dd3fade19496d91bd6a017e435a96a6bcd x86_64 hpack-0.17.0

[PierreVDL]

Can this issue be reopened?

[mgsloan]

@PierreVDL @Topsii I've pushed a fix to master. The solution is to only mark the package as a target if some of its components are targets.