testsuite: Add two tests for independent goals (haskell#9466)

These tests check how constraints interact with the --independent-goals
flag.

Author: mpickering

cabal-install/tests/UnitTests/Distribution/Solver/Modular/Solver.hs

@@ -361,6 +361,8 @@ tests =
       , runTest $ testIndepGoals5 "indepGoals5 - default goal order" DefaultGoalOrder
       , runTest $ testIndepGoals6 "indepGoals6 - fixed goal order" FixedGoalOrder
       , runTest $ testIndepGoals6 "indepGoals6 - default goal order" DefaultGoalOrder
+      , expectFailBecause "#9466" $ runTest $ testIndepGoals7 "indepGoals7"
+      , runTest $ testIndepGoals8 "indepGoals8"
       ]
   , -- Tests designed for the backjumping blog post
     testGroup
@@ -2013,6 +2015,41 @@ dbLangs1 =
   , Right $ exAv "C" 1 [ExLang (UnknownLanguage "Haskell3000"), ExAny "B"]
   ]
 
+-- This test checks how the scope of a constraint interacts with qualified goals.
+-- If you specify `B == 2`, then should that apply to an independent goal or not?
+testIndepGoals7 :: String -> SolverTest
+testIndepGoals7 name =
+  constraints [ExVersionConstraint (scopeToplevel "B") (V.thisVersion (V.mkVersion [2, 0, 0]))] $
+    independentGoals $
+      mkTest db name ["A"] $
+        -- TODO: Place correct string here when it fails
+        solverFailure (const False)
+  where
+    db :: ExampleDb
+    db =
+      [ Right $ exAv "A" 1 [ExAny "B"]
+      , Right $ exAv "B" 1 [ExAny "does-not-exist"]
+      , Right $ exAv "B" 2 []
+      , Right $ exAv "B" 3 [ExAny "does-not-exist"]
+      ]
+
+-- This test checks how the scope of a constraint interacts with qualified goals.
+-- If you specify `any.B == 2`, then that should apply inside an independent goal.
+testIndepGoals8 :: String -> SolverTest
+testIndepGoals8 name =
+  constraints [ExVersionConstraint (ScopeAnyQualifier "B") (V.thisVersion (V.mkVersion [2, 0, 0]))] $
+    independentGoals $
+      mkTest db name ["A"] $
+        solverSuccess [("A", 1), ("B", 2)]
+  where
+    db :: ExampleDb
+    db =
+      [ Right $ exAv "A" 1 [ExAny "B"]
+      , Right $ exAv "B" 1 []
+      , Right $ exAv "B" 2 []
+      , Right $ exAv "B" 3 []
+      ]
+
 -- | cabal must set enable-exe to false in order to avoid the unavailable
 -- dependency. Flags are true by default. The flag choice causes "pkg" to
 -- depend on "false-dep".