cabal-install/tests/IntegrationTests2.hs is sensitive to local configuration

[geekosaur]

Describe the bug
If my local cabal configuration contains documentation: True, running validate.sh locally fails with

Integration tests (internal)
  Regression tests
    program options scope all:                 FAIL (1.36s)
      tests/IntegrationTests2.hs:1560:
      q
      expected: Just ["-fno-full-laziness"]
       but got: Just ["-haddock"]
      Use -p '/program options scope all/' to rerun this test only.
    program options scope local:               FAIL (1.26s)
      tests/IntegrationTests2.hs:1585:
      q
      expected: Just ["-fno-full-laziness"]
       but got: Just ["-haddock"]
      Use -p '/program options scope local/' to rerun this test only.
    program options scope specific:            FAIL (1.33s)
      tests/IntegrationTests2.hs:1610:
      q
      expected: Nothing
       but got: Just ["-haddock"]
      Use -p '/program options scope specific/' to rerun this test only.

Validation succeeds if I comment out the documentation directive in my local config.

To Reproduce
Steps to reproduce the behavior:

$ vi ~/.config/cabal/config # and set "documentation: True"
$ git clone https://github.com/haskell/cabal
$ cd cabal
$ cabal build all
$ ./validate.sh --with-cabal=$(cabal list-bin cabal)

Expected behavior
Validation should succeed regardless of the local setting of documentation.

System information

• Linux Ubuntu 22.04.3
• cabal master HEAD as of 2024-07-08, ghc 9.6.6

[geekosaur]

Should validate.sh point to a default config file via CABAL_CONFIG, or does it need to use some other mechanism to avoid overriding test-specific config files?

[ulysses4ever]

dunno but perhaps if you do something wrong and override the test-specific configs it will fail horribly?..

[geekosaur]

It looks like IntegrationTests2 already has a default cabal config; it's just not using it, as far as I can tell, or at least isn't using it everywhere it needs to be used. I'm thinking that needs to be moved into validate.sh.