python driver: preserve trailing quotes in agtype string values (#2425)

* python driver: preserve trailing quotes in agtype string values

str.strip('"') in visitStringValue() and visitPair() removes every '"'
on either side of the token, not just the outer delimiters, so a value
ending in an escaped quote (e.g. '"foo \"bar\""') loses its trailing
backslash-escaped '"' character.  The Agtype grammar guarantees STRING
tokens always carry exactly one delimiter on each side, so slice with
[1:-1] to strip them precisely.

Fixes #2418

Signed-off-by: SAY-5 <saiasish.cnp@gmail.com>

* fix(python-driver): centralize string delimiter trim and clean test docstring

---------

Signed-off-by: SAY-5 <saiasish.cnp@gmail.com>

Author: SAY-5

drivers/python/age/builder.py

@@ -105,9 +105,16 @@ def visitAgValue(self, ctx:AgtypeParser.AgValueContext):
             return valueCtx.accept(self)
 
 
+    @staticmethod
+    def _stripStringDelimiters(stringToken):
+        # The STRING token always has surrounding '"' delimiters per the
+        # Agtype grammar; slice rather than strip('"') so escaped quotes
+        # at the boundaries are preserved.
+        return stringToken.getText()[1:-1]
+
     # Visit a parse tree produced by AgtypeParser#StringValue.
     def visitStringValue(self, ctx:AgtypeParser.StringValueContext):
-        return ctx.STRING().getText().strip('"')
+        return self._stripStringDelimiters(ctx.STRING())
 
 
     # Visit a parse tree produced by AgtypeParser#IntegerValue.
@@ -182,7 +189,7 @@ def visitPair(self, ctx:AgtypeParser.PairContext):
             raise AGTypeError(ctx.getText(), "Missing key in object pair")
         if agValNode is None:
             raise AGTypeError(ctx.getText(), "Missing value in object pair")
-        return (strNode.getText().strip('"') , agValNode)
+        return (self._stripStringDelimiters(strNode), agValNode)
 
 
     # Visit a parse tree produced by AgtypeParser#array.

drivers/python/test_agtypes.py

@@ -245,6 +245,22 @@ def test_array_of_mixed_types(self):
         self.assertEqual(result[4], [1, 2, 3])
         self.assertEqual(result[5], {"key": "val"})
 
+    def test_string_value_preserves_inner_quotes(self):
+        """Issue #2418: preserve escaped boundary quotes when stripping.
+
+        visitStringValue must strip only the outer delimiters; otherwise
+        values like '"foo \\"bar\\""' lose their trailing escaped quote.
+        """
+        self.assertEqual(self.parse('"foo \\"bar\\""'), 'foo \\"bar\\"')
+        self.assertEqual(self.parse('"\\"leading"'), '\\"leading')
+        self.assertEqual(self.parse('"trailing\\""'), 'trailing\\"')
+        self.assertEqual(self.parse('""'), '')
+        # Same fix applies to visitPair() for object keys.
+        self.assertEqual(
+            self.parse('{"key\\"q": 1}'),
+            {'key\\"q': 1},
+        )
+
     def test_malformed_vertex_raises_agtypeerror_or_recovers(self):
         """Issue #2367: Malformed agtype must raise AGTypeError or recover gracefully."""
         from age.exceptions import AGTypeError