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

Author: SAY-5

drivers/python/age/builder.py

@@ -105,14 +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):
-        # The STRING token always has surrounding '"' delimiters per the
-        # Agtype grammar.  str.strip('"') would also drop any '"' characters
-        # that are part of the actual data when the value starts or ends
-        # with an escaped quote, e.g. '"foo \\"bar\\""' -> 'foo \\"bar\\',
-        # so trim exactly the first and last character instead.
-        return ctx.STRING().getText()[1:-1]
+        return self._stripStringDelimiters(ctx.STRING())
 
 
     # Visit a parse tree produced by AgtypeParser#IntegerValue.
@@ -187,8 +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")
-        # See visitStringValue() for why we slice instead of using strip('"').
-        return (strNode.getText()[1:-1] , agValNode)
+        return (self._stripStringDelimiters(strNode), agValNode)
 
 
     # Visit a parse tree produced by AgtypeParser#array.

drivers/python/test_agtypes.py

@@ -246,9 +246,11 @@ def test_array_of_mixed_types(self):
         self.assertEqual(result[5], {"key": "val"})
 
     def test_string_value_preserves_inner_quotes(self):
-        """Issue #2418: visitStringValue must remove only the outer quote
-        delimiters, not every '"' on either side, otherwise values that end
-        with an escaped quote (e.g. '"foo \\"bar\\""') lose data."""
+        """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\\"')