Add test-case for show-casing issue #7395

cabal-testsuite/PackageTests/Ambiguity/multiple-cabal-files/Main.hs

@@ -0,0 +1,4 @@
+module Main where
+
+main :: IO ()
+main = putStrLn "Hello, Haskell!"

cabal-testsuite/PackageTests/Ambiguity/multiple-cabal-files/cabal.project

@@ -0,0 +1 @@
+packages: multiple-cabal-files.cabal multiple-cabal-files2.cabal

cabal-testsuite/PackageTests/Ambiguity/multiple-cabal-files/multiple-cabal-files.cabal

@@ -0,0 +1,7 @@
+cabal-version:      2.4
+name:               multiple-cabal-files
+version:            0.1.0.0
+
+executable exe
+    main-is: Main.hs
+

cabal-testsuite/PackageTests/Ambiguity/multiple-cabal-files/multiple-cabal-files2.cabal

@@ -0,0 +1,7 @@
+cabal-version:      2.4
+name:               multiple-cabal-files
+version:            0.1.0.0
+
+executable exe
+    main-is: Main.hs
+

cabal-testsuite/PackageTests/Ambiguity/setup-cabal-file.out

@@ -0,0 +1,4 @@
+# cabal v2-build
+Error: cabal: Multiple packages have been found:
+multiple-cabal-files-0.1.0.0 defined in: ./multiple-cabal-files.cabal
+multiple-cabal-files-0.1.0.0 defined in: ./multiple-cabal-files2.cabal

cabal-testsuite/PackageTests/Ambiguity/setup-cabal-file.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+-- Test that we can resolve a module name ambiguity when reexporting
+-- by explicitly specifying what package we want.
+main = cabalTest $ withDirectory "multiple-cabal-files" $
+    fails $ cabal "v2-build" []