GHC.DiagnosticSpec: Add more tests

test/GHC/DiagnosticSpec.hs

@@ -28,7 +28,7 @@ test name = it name $ do
       bin <- lookupGhc <$> getEnvironment
       let
         process :: CreateProcess
-        process = proc bin (args ++ [dir </> "Foo.hs"])
+        process = proc bin ("-fno-code" : args ++ [dir </> "Foo.hs"])
       (_, _, err) <- readCreateProcessWithExitCode process ""
       return err
 
@@ -51,3 +51,5 @@ spec = do
     test "variable-not-in-scope-perhaps-use"
     test "use-BlockArguments"
     test "non-existing"
+    test "parse-error"
+    test "lex-error"

test/assets/lex-error/Foo.hs

@@ -0,0 +1,3 @@
+module Foo where
+
+foo = "bar

test/assets/lex-error/err.json

@@ -0,0 +1 @@
+{"version":"1.0","ghcVersion":"ghc-9.10.1","span":{"file":"test/assets/lex-error/Foo.hs","start":{"line":3,"column":11},"end":{"line":3,"column":11}},"severity":"Error","code":21231,"message":["lexical error in string/character literal at character '\\n'"],"hints":[]}

test/assets/lex-error/err.out

@@ -0,0 +1,3 @@
+test/assets/lex-error/Foo.hs:3:11: error: [GHC-21231]
+    lexical error in string/character literal at character '\n'
+

test/assets/parse-error/Foo.hs

@@ -0,0 +1,3 @@
+module Foo where
+
+data foo

test/assets/parse-error/err.json

@@ -0,0 +1 @@
+{"version":"1.0","ghcVersion":"ghc-9.10.1","span":{"file":"test/assets/parse-error/Foo.hs","start":{"line":3,"column":6},"end":{"line":3,"column":9}},"severity":"Error","code":47568,"message":["Malformed head of type or class declaration: foo"],"hints":[]}

test/assets/parse-error/err.out

@@ -0,0 +1,3 @@
+test/assets/parse-error/Foo.hs:3:6: error: [GHC-47568]
+    Malformed head of type or class declaration: foo
+