fresh config for cabal-install integration tests

`validate.sh` locally was being affected by my local cabal config,
leading to test failures (specifically, because I have
`documentation: True` in my config).

Note that this adds a fresh config file to the repo, which will
need to be kept up to date. The alternative is to have it create
one at the start of the tests.

cabal-install/tests/IntegrationTests2.hs

@@ -74,6 +74,7 @@ import Control.Concurrent (threadDelay)
 import Control.Exception hiding (assert)
 import System.FilePath
 import System.Directory
+import System.Environment (setEnv)
 import System.IO (hPutStrLn, stderr)
 
 import Test.Tasty
@@ -93,7 +94,9 @@ removePathForcibly = removeDirectoryRecursive
 #endif
 
 main :: IO ()
-main =
+main = do
+  -- this is needed to ensure tests aren't affected by the user's cabal config
+  setEnv "CABAL_CONFIG" (basedir </> "config" </> "cabal.config")
   defaultMainWithIngredients
     (defaultIngredients ++ [includingOptions projectConfigOptionDescriptions])
     (withProjectConfig $ \config ->
@@ -1971,8 +1974,8 @@ testNixFlags = do
 -- Tests whether config options are commented or not
 testConfigOptionComments :: Assertion
 testConfigOptionComments = do
-  _ <- createDefaultConfigFile verbosity [] (basedir </> "config/default-config")
-  defaultConfigFile <- readFile (basedir </> "config/default-config")
+  _ <- createDefaultConfigFile verbosity [] (basedir </> "config" </> "default-config")
+  defaultConfigFile <- readFile (basedir </> "config" </> "default-config")
 
   "  url" @=? findLineWith False "url" defaultConfigFile
   "  -- secure" @=? findLineWith True "secure" defaultConfigFile

tests/IntegrationTests2/config/cabal.config

@@ -0,0 +1,249 @@
+-- This is the configuration file for the 'cabal' command line tool.
+--
+-- The available configuration options are listed below.
+-- Some of them have default values listed.
+--
+-- Lines (like this one) beginning with '--' are comments.
+-- Be careful with spaces and indentation because they are
+-- used to indicate layout for nested sections.
+--
+-- This config file was generated using the following versions
+-- of Cabal and cabal-install:
+-- Cabal library version: 3.11.0.0
+-- cabal-install version: 3.11
+
+
+repository hackage.haskell.org
+  url: http://hackage.haskell.org/
+  -- secure: True
+  -- root-keys:
+  -- key-threshold: 3
+
+-- ignore-expiry: False
+-- http-transport:
+-- nix:
+-- store-dir:
+-- active-repositories:
+-- local-no-index-repo:
+remote-repo-cache: /Users/finley/.cabal/packages
+-- logs-dir: /Users/finley/.cabal/logs
+-- default-user-config:
+-- verbose: 1
+-- compiler: ghc
+-- cabal-file:
+-- with-compiler:
+-- with-hc-pkg:
+-- program-prefix: 
+-- program-suffix: 
+-- library-vanilla: True
+-- library-profiling:
+-- shared:
+-- static:
+-- executable-dynamic: False
+-- executable-static: False
+-- profiling:
+-- executable-profiling:
+-- profiling-detail:
+-- library-profiling-detail:
+-- optimization: True
+-- debug-info: False
+-- build-info:
+-- library-for-ghci:
+-- split-sections: False
+-- split-objs: False
+-- executable-stripping:
+-- library-stripping:
+-- configure-option:
+-- user-install: True
+-- package-db:
+-- flags:
+-- extra-include-dirs:
+-- deterministic:
+-- cid:
+-- extra-lib-dirs:
+-- extra-lib-dirs-static:
+-- extra-framework-dirs:
+-- extra-prog-path:
+-- instantiate-with:
+-- tests: False
+-- coverage: False
+-- library-coverage:
+-- exact-configuration: False
+-- benchmarks: False
+-- relocatable: False
+-- response-files:
+-- allow-depending-on-private-libs:
+-- cabal-lib-version:
+-- append:
+-- backup:
+-- constraint:
+-- preference:
+-- solver: modular
+-- allow-older: False
+-- allow-newer: False
+-- write-ghc-environment-files:
+-- documentation: False
+-- doc-index-file: $datadir/doc/$arch-$os-$compiler/index.html
+-- only-download: False
+-- target-package-db:
+-- max-backjumps: 4000
+-- reorder-goals: False
+-- count-conflicts: True
+-- fine-grained-conflicts: True
+-- minimize-conflict-set: False
+-- independent-goals: False
+-- prefer-oldest: False
+-- shadow-installed-packages: False
+-- strong-flags: False
+-- allow-boot-library-installs: False
+-- reject-unconstrained-dependencies: none
+-- reinstall: False
+-- avoid-reinstalls: False
+-- force-reinstalls: False
+-- upgrade-dependencies: False
+-- index-state:
+-- root-cmd:
+-- symlink-bindir:
+build-summary: /Users/finley/.cabal/logs/build.log
+-- build-log:
+remote-build-reporting: none
+-- report-planning-failure: False
+-- per-component: True
+-- run-tests:
+-- semaphore: False
+jobs: $ncpus
+-- keep-going: False
+-- offline: False
+-- lib: False
+-- package-env:
+-- overwrite-policy:
+-- install-method:
+installdir: /Users/finley/.cabal/bin
+-- username:
+-- password:
+-- password-command:
+-- multi-repl:
+-- builddir:
+
+haddock
+  -- keep-temp-files: False
+  -- hoogle: False
+  -- html: False
+  -- html-location:
+  -- executables: False
+  -- tests: False
+  -- benchmarks: False
+  -- foreign-libraries: False
+  -- all:
+  -- internal: False
+  -- css:
+  -- hyperlink-source: False
+  -- quickjump: False
+  -- hscolour-css:
+  -- contents-location:
+  -- index-location:
+  -- base-url:
+  -- resources-dir:
+  -- output-dir:
+  -- use-unicode: False
+
+init
+  -- interactive: False
+  -- quiet: False
+  -- no-comments: False
+  -- minimal: False
+  -- cabal-version: 3.0
+  -- license:
+  -- extra-doc-file:
+  -- tests:
+  -- test-dir:
+  -- simple: False
+  -- language: Haskell2010
+  -- application-dir: app
+  -- source-dir: src
+
+install-dirs user
+  -- prefix: /Users/finley/.cabal
+  -- bindir: $prefix/bin
+  -- libdir: $prefix/lib
+  -- libsubdir: $abi/$libname
+  -- dynlibdir: $libdir/$abi
+  -- libexecdir: $prefix/libexec
+  -- libexecsubdir: $abi/$pkgid
+  -- datadir: $prefix/share
+  -- datasubdir: $abi/$pkgid
+  -- docdir: $datadir/doc/$abi/$pkgid
+  -- htmldir: $docdir/html
+  -- haddockdir: $htmldir
+  -- sysconfdir: $prefix/etc
+
+install-dirs global
+  -- prefix: /usr/local
+  -- bindir: $prefix/bin
+  -- libdir: $prefix/lib
+  -- libsubdir: $abi/$libname
+  -- dynlibdir: $libdir/$abi
+  -- libexecdir: $prefix/libexec
+  -- libexecsubdir: $abi/$pkgid
+  -- datadir: $prefix/share
+  -- datasubdir: $abi/$pkgid
+  -- docdir: $datadir/doc/$abi/$pkgid
+  -- htmldir: $docdir/html
+  -- haddockdir: $htmldir
+  -- sysconfdir: $prefix/etc
+
+program-locations
+  -- alex-location:
+  -- ar-location:
+  -- c2hs-location:
+  -- cpphs-location:
+  -- doctest-location:
+  -- gcc-location:
+  -- ghc-location:
+  -- ghc-pkg-location:
+  -- ghcjs-location:
+  -- ghcjs-pkg-location:
+  -- greencard-location:
+  -- haddock-location:
+  -- happy-location:
+  -- haskell-suite-location:
+  -- haskell-suite-pkg-location:
+  -- hmake-location:
+  -- hpc-location:
+  -- hsc2hs-location:
+  -- hscolour-location:
+  -- jhc-location:
+  -- ld-location:
+  -- pkg-config-location:
+  -- runghc-location:
+  -- strip-location:
+  -- tar-location:
+  -- uhc-location:
+
+program-default-options
+  -- alex-options:
+  -- ar-options:
+  -- c2hs-options:
+  -- cpphs-options:
+  -- doctest-options:
+  -- gcc-options:
+  -- ghc-options:
+  -- ghc-pkg-options:
+  -- ghcjs-options:
+  -- ghcjs-pkg-options:
+  -- greencard-options:
+  -- haddock-options:
+  -- happy-options:
+  -- haskell-suite-options:
+  -- haskell-suite-pkg-options:
+  -- hmake-options:
+  -- hpc-options:
+  -- hsc2hs-options:
+  -- hscolour-options:
+  -- jhc-options:
+  -- ld-options:
+  -- pkg-config-options:
+  -- runghc-options:
+  -- strip-options:
+  -- tar-options:
+  -- uhc-options: