From dbe5cf42d2de1a74ce363b2514fc51de3e673ae8 Mon Sep 17 00:00:00 2001
From: Matthew Pickering <matthewtpickering@gmail.com>
Date: Fri, 19 Jan 2024 19:49:05 +0000
Subject: [PATCH] Don't inherit package database to tests

I can't think of a reason why it would be desirable to expose the user's
cabal store or local dist-newstyle to the test runner. In fact, this can
break test output in certain situations depending on what is in your
store.

Tests should run in as hemertic environment as possible and not
depend on anything to do with external system configuration.

I have introduced a Note [Testsuite package environments] which explains
what the environments are for the three different components of the
testsuite.

{- Note [Testsuite package environments]

There are three different package environments which are used when running the
testsuite.

1. Environment used to compile `cabal-tests` executable
2. Environment used to run test scripts "setup.test.hs"
3. Environment made available to tests themselves via `./Setup configure`

These are all distinct from each other and should be specified separately.

Where are these environments specified:

1. The build-depends on `cabal-tests` executable in `cabal-testsuite.cabal`
2. The build-depends of `test-runtime-deps` executable in `cabal-testsuite.cabal`
   These dependencies are injected in a special module (`Test.Cabal.ScriptEnv0`) which
   then is consulted in `Test.Cabal.Monad` in order to pass the right environmnet.
   This is mechanism by which the `./Setup` tests have access to the in-tree `Cabal`
   and `Cabal-syntax` libraries.
3. No specification, only the `GlobalPackageDb` is available (see
   `testPackageDBStack`) unless the test itself augments the environment with
   `withPackageDb`.

At the moment, `cabal-install` tests always use the bootstrap cabal, which is a
bit confusing but `cabal-install` is not flexible enough to be given additional
package databases (yet).

-}
---
 cabal-testsuite/main/cabal-tests.hs     | 29 +++++++++++++++++++++++++++++
 cabal-testsuite/src/Test/Cabal/Monad.hs | 19 +------------------
 2 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/cabal-testsuite/main/cabal-tests.hs b/cabal-testsuite/main/cabal-tests.hs
index 2ea070bff..8f8e8ec28 100644
--- a/cabal-testsuite/main/cabal-tests.hs
+++ b/cabal-testsuite/main/cabal-tests.hs
@@ -34,6 +34,35 @@ import Data.Monoid ((<>))
 import Data.Monoid (mempty)
 #endif
 
+{- Note [Testsuite package environments]
+
+There are three different package environments which are used when running the
+testsuite.
+
+1. Environment used to compile `cabal-tests` executable
+2. Environment used to run test scripts "setup.test.hs"
+3. Environment made available to tests themselves via `./Setup configure`
+
+These are all distinct from each other and should be specified separately.
+
+Where are these environments specified:
+
+1. The build-depends on `cabal-tests` executable in `cabal-testsuite.cabal`
+2. The build-depends of `test-runtime-deps` executable in `cabal-testsuite.cabal`
+   These dependencies are injected in a special module (`Test.Cabal.ScriptEnv0`) which
+   then is consulted in `Test.Cabal.Monad` in order to pass the right environmnet.
+   This is mechanism by which the `./Setup` tests have access to the in-tree `Cabal`
+   and `Cabal-syntax` libraries.
+3. No specification, only the `GlobalPackageDb` is available (see
+   `testPackageDBStack`) unless the test itself augments the environment with
+   `withPackageDb`.
+
+At the moment, `cabal-install` tests always use the bootstrap cabal, which is a
+bit confusing but `cabal-install` is not flexible enough to be given additional
+package databases (yet).
+
+-}
+
 -- | Record for arguments that can be passed to @cabal-tests@ executable.
 data MainArgs = MainArgs {
         mainArgThreads :: Int,
diff --git a/cabal-testsuite/src/Test/Cabal/Monad.hs b/cabal-testsuite/src/Test/Cabal/Monad.hs
index c1ecf3dfe..366217733 100644
--- a/cabal-testsuite/src/Test/Cabal/Monad.hs
+++ b/cabal-testsuite/src/Test/Cabal/Monad.hs
@@ -289,24 +289,7 @@ runTestM mode m = withSystemTempDirectory "cabal-testsuite" $ \tmp_dir -> do
     -- them up we must configure them
     program_db <- configureAllKnownPrograms verbosity program_db3
 
-    let ghcAndRunnedGhcAreTheSame :: Bool
-        ghcAndRunnedGhcAreTheSame = fromMaybe False $ do
-            ghc_program        <- lookupProgram ghcProgram program_db
-            runner_ghc_program <- lookupProgram ghcProgram (runnerProgramDb senv)
-            return $ programPath ghc_program == programPath runner_ghc_program
-
-    let db_stack =
-            case argGhcPath (testCommonArgs args) of
-                Nothing -> runnerPackageDbStack senv -- NB: canonicalized
-                -- Can't use the build package db stack since they
-                -- are all for the wrong versions!  TODO: Make
-                -- this configurable
-                --
-                -- Oleg: if runner ghc and provided ghc are the same,
-                -- use runnerPackageDbStack. See 'hasCabalForGhc' check.
-                Just _
-                    | ghcAndRunnedGhcAreTheSame -> runnerPackageDbStack senv
-                    | otherwise                 -> [GlobalPackageDB]
+    let db_stack = [GlobalPackageDB]
         env = TestEnv {
                     testSourceDir = script_dir,
                     testTmpDir = tmp_dir,
-- 
2.11.4.GIT