Currently, cabal-testsuite (which seems to be the main way cabal the binary is tested) cannot be used as a stand-alone binary to run the tests.

The reasons seem to be:

• it requires sources that are part of the repository
• there is a generated module that depends on the current cached LocalBuildInfo and hardcodes it into the binary, which then is used to reconstruct arguments to ghc when compiling tests
  • it's not clear to me whether this is only required for the Setup.hs tests or the cabal-install binary tests as well (e.g. there is --skip-setup-tests but my observation is that this isn't really enough)

The end goal I have is:

• build and test is strictly separated in CI and the test step does not involve building anything other than the tests
• tests can be run on the end users system (ultimately through GHCup)