Add a test case involving -fno-warn-missing-signatures (#720)

* Only enable non-fatal warnings

* Revert the change since it has been taken care of in #738

test/data/ignore-fatal/IgnoreFatal.hs

@@ -0,0 +1,8 @@
+-- "missing signature" is declared a fatal warning in the cabal file,
+-- but is ignored in this module.
+
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+
+module IgnoreFatal where
+
+a = 'a'

test/data/ignore-fatal/cabal.project

@@ -0,0 +1 @@
+packages: ignore-fatal.cabal

test/data/ignore-fatal/hie.yaml

@@ -0,0 +1,4 @@
+cradle:
+  cabal:
+    - path: "."
+      component: "lib:ignore-fatal"

test/data/ignore-fatal/ignore-fatal.cabal

@@ -0,0 +1,10 @@
+name: ignore-fatal
+version: 1.0.0
+build-type: Simple
+cabal-version: >= 1.2
+
+library
+  build-depends: base
+  exposed-modules: IgnoreFatal
+  hs-source-dirs: .
+  ghc-options: -Werror=missing-signatures

test/exe/Main.hs

@@ -2786,6 +2786,7 @@ haddockTests
 cradleTests :: TestTree
 cradleTests = testGroup "cradle"
     [testGroup "dependencies" [sessionDepsArePickedUp]
+    ,testGroup "ignore-fatal" [ignoreFatalWarning]
     ,testGroup "loading" [loadCradleOnlyonce]
     ,testGroup "multi"   [simpleMultiTest, simpleMultiTest2]
     ]
@@ -2875,6 +2876,13 @@ withoutStackEnv s =
         restore var Nothing = unsetEnv var
         restore var (Just val) = setEnv var val True
 
+ignoreFatalWarning :: TestTree
+ignoreFatalWarning = testCase "ignore-fatal-warning" $ withoutStackEnv $ runWithExtraFiles "ignore-fatal" $ \dir -> do
+    let srcPath = dir </> "IgnoreFatal.hs"
+    src <- liftIO $ readFileUtf8 srcPath
+    _ <- createDoc srcPath "haskell" src
+    expectNoMoreDiagnostics 5
+
 simpleMultiTest :: TestTree
 simpleMultiTest = testCase "simple-multi-test" $ withoutStackEnv $ runWithExtraFiles "multi" $ \dir -> do
     let aPath = dir </> "a/A.hs"