Add reproducer for bug in OPTIONS_GHC completions (#3908)

Author: jhrcek

plugins/hls-pragmas-plugin/test/Main.hs

@@ -125,6 +125,7 @@ completionTests =
   , completionTest "completes pragmas with existing closing bracket" "Completion.hs" "" "LANGUAGE" (Just InsertTextFormat_Snippet) (Just "LANGUAGE ${1:extension} #-") (Just "{-# LANGUAGE #-}") (0, 4, 0, 33, 0, 4)
   , completionTest "completes options pragma" "Completion.hs" "OPTIONS" "OPTIONS_GHC" (Just InsertTextFormat_Snippet) (Just "OPTIONS_GHC -${1:option} #-}") (Just "{-# OPTIONS_GHC #-}") (0, 4, 0, 34, 0, 4)
   , completionTest "completes ghc options pragma values" "Completion.hs" "{-# OPTIONS_GHC -Wno-red  #-}\n" "Wno-redundant-constraints" Nothing Nothing Nothing (0, 0, 0, 0, 0, 24)
+  , completionTest "completes ghc options pragma values with multiple dashes" "Completion.hs" "{-# OPTIONS_GHC -dsuppress-constant-fo #-}\n" "dsuppress-constant-folding" Nothing Nothing Nothing (0, 0, 0, 0, 0, 38)
   , completionTest "completes language extensions" "Completion.hs" "" "OverloadedStrings" Nothing Nothing Nothing (0, 24, 0, 31, 0, 24)
   , completionTest "completes language extensions case insensitive" "Completion.hs" "lAnGuaGe Overloaded" "OverloadedStrings" Nothing Nothing Nothing (0, 4, 0, 34, 0, 24)
   , completionTest "completes the Strict language extension" "Completion.hs" "Str" "Strict" Nothing Nothing Nothing (0, 13, 0, 31, 0, 16)