Fix crash on empty values

CHANGELOG.md

@@ -10,6 +10,8 @@ New features:
 
 Bugfixes:
 
+- Empty values (`A=`, `A=""`, `A=''`) are now parsed as the empty string instead of failing to parse.
+
 Other improvements:
 
 ## [4.0.3] - 2023-08-05

src/Dotenv/Internal/Parser.purs

@@ -76,7 +76,7 @@ quotedValue q =
   in
     valueFromValues <$>
       ( char q
-          *> (some $ variableSubstitution <|> commandSubstitution <|> literal)
+          *> (many $ variableSubstitution <|> commandSubstitution <|> literal)
           <* char q
       )
 
@@ -97,12 +97,13 @@ unquotedValue =
   in
     valueFromValues <$>
       ( whiteSpace *>
-          (some $ variableSubstitution <|> commandSubstitution <|> literal)
+          (many $ variableSubstitution <|> commandSubstitution <|> literal)
       )
 
 -- | Assembles a single value from a series of values.
 valueFromValues :: Array UnresolvedValue -> UnresolvedValue
 valueFromValues v
+  | length v == 0 = LiteralValue ""
   | length v == 1 = fromMaybe (ValueExpression []) (head v)
   | otherwise = ValueExpression v
 

test/Parse.purs

@@ -159,4 +159,11 @@ tests = describe "parser" do
           ]
       actual = runParser "A=\"Hello, $(head -n 1 user.txt)!\"" parser
     in
-      actual `shouldEqual` expected
+      actual `shouldEqual` expected
+
+  it "parses an empty value as the empty string" $
+    let
+      expected = Right [ "A" /\ LiteralValue "" ]
+      actual = runParser "A=" parser
+    in
+      actual `shouldEqual` expected