Add failing test for missing warnings #507

ghc-mod.cabal

@@ -71,6 +71,7 @@ Extra-Source-Files:     ChangeLog
                         test/data/pattern-synonyms/*.hs
                         test/data/quasi-quotes/*.hs
                         test/data/template-haskell/*.hs
+                        test/data/check-missing-warnings/*.hs
 
 Library
   Default-Language:     Haskell2010

test/CheckSpec.hs

@@ -52,3 +52,8 @@ spec = do
                 withDirectory_ "test/data/ghc-mod-check/lib/Data" $ do
                     res <- runD $ checkSyntax ["Foo.hs"]
                     res `shouldBe` ""
+
+        it "emits warnings generated in GHC's desugar stage" $ do
+            withDirectory_ "test/data/check-missing-warnings" $ do
+                res <- runD $ checkSyntax ["DesugarWarnings.hs"]
+                res `shouldBe` "test/data/check-missing-warnings/DesugarWarnings.hs:5:9:Warning: Pattern match(es) are non-exhaustiveIn a case alternative: Patterns not matched: _ : _"

test/data/check-missing-warnings/DesugarWarnings.hs

@@ -0,0 +1,5 @@
+module Warnings (zoo) where
+
+zoo :: [a] -> ()
+zoo x = case x of
+          [] -> undefined