Add test for no errors case

test/CheckSpec.hs

@@ -34,3 +34,10 @@ spec = do
                 cradle <- findCradleWithoutSandbox
                 res <- checkSyntax defaultOptions cradle ["Baz.hs"]
                 res `shouldSatisfy` ("Baz.hs:5:1:Warning:" `isPrefixOf`)
+
+        context "without errors" $ do
+            it "doesn't output empty line" $ do
+                withDirectory_ "test/data/ghc-mod-check/Data" $ do
+                    cradle <- findCradleWithoutSandbox
+                    res <- checkSyntax defaultOptions cradle ["Foo.hs"]
+                    res `shouldBe` ""

test/LintSpec.hs

@@ -10,3 +10,7 @@ spec = do
             res <- lintSyntax defaultOptions "test/data/hlint.hs"
             res `shouldBe` "test/data/hlint.hs:4:8: Error: Redundant do\NULFound:\NUL  do putStrLn \"Hello, world!\"\NULWhy not:\NUL  putStrLn \"Hello, world!\"\n"
 
+        context "without suggestions" $ do
+            it "doesn't output empty line" $ do
+                res <- lintSyntax defaultOptions "test/data/ghc-mod-check/Data/Foo.hs"
+                res `shouldBe` ""