python driver: preserve trailing quotes in agtype string values

drivers/python/age/builder.py

@@ -107,7 +107,12 @@ def visitAgValue(self, ctx:AgtypeParser.AgValueContext):
 
     # Visit a parse tree produced by AgtypeParser#StringValue.
     def visitStringValue(self, ctx:AgtypeParser.StringValueContext):
-        return ctx.STRING().getText().strip('"')
+        # 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]
 
 
     # Visit a parse tree produced by AgtypeParser#IntegerValue.
@@ -182,7 +187,8 @@ 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)
+        # See visitStringValue() for why we slice instead of using strip('"').
+        return (strNode.getText()[1:-1] , agValNode)
 
 
     # Visit a parse tree produced by AgtypeParser#array.

drivers/python/test_agtypes.py

@@ -245,6 +245,20 @@ 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: 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."""
+        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