fix: Correctly parse newline and multiline strings in dotenv files (#192

)

* test: Add tests for correctly escaping new lines characters `\n`

* fix: Correctly parse newline and multiline strings in dotenv files

* test: Enhance test cases for more robust `\n`

spec/Configuration/Dotenv/TextSpec.hs

@@ -27,3 +27,11 @@ spec =
     it "recognizes unicode characters" $
       liftM (!! 1) (parseFile "spec/fixtures/.dotenv") `shouldReturn`
         (T.pack "UNICODE_TEST", T.pack "Manabí")
+
+    it "handles newline characters correctly" $ do
+      liftM (!! 6) (parseFile "spec/fixtures/.dotenv") `shouldReturn`
+        (T.pack "NEWLINE_TEST", T.pack "Hello\nWorld\nThis is a test\n")
+
+    it "handles manual line breaks correctly" $ do
+      liftM (!! 7) (parseFile "spec/fixtures/.dotenv") `shouldReturn`
+        (T.pack "MULTILINE_TEST", T.pack "Roses are red\nViolets are blue\nCode is my art\nAnd bugs are my glue\n")

spec/fixtures/.dotenv

@@ -4,3 +4,9 @@ ENVIRONMENT="$HOME"
 PREVIOUS="$DOTENV"
 ME="$(whoami)"
 BLANK=
+NEWLINE_TEST="Hello\nWorld\nThis is a test\n"
+MULTILINE_TEST="Roses are red
+Violets are blue
+Code is my art
+And bugs are my glue
+"

src/Configuration/Dotenv/Parse.hs

@@ -25,7 +25,7 @@ import           Text.Megaparsec                     (Parsec, anySingle,
                                                       between, eof, noneOf,
                                                       oneOf, sepEndBy, (<?>))
 import           Text.Megaparsec.Char                (char, digitChar, eol,
-                                                      letterChar, spaceChar)
+                                                      letterChar, spaceChar, string)
 import qualified Text.Megaparsec.Char.Lexer          as L
 
 type Parser = Parsec Void String
@@ -85,8 +85,9 @@ interpolatedValueCommandInterpolation = do
       symbol = L.symbol sc
 
 literalValueFragment :: String -> Parser VarFragment
-literalValueFragment charsToEscape = VarLiteral <$> some (escapedChar <|> normalChar)
+literalValueFragment charsToEscape = VarLiteral <$> some (newlineChar <|> escapedChar <|> normalChar)
   where
+    newlineChar  = string "\\n" >> return '\n'
     escapedChar = (char '\\' *> anySingle) <?> "escaped character"
     normalChar  = noneOf charsToEscape <?> "unescaped character"