Incorrect parsing of string with trailing \"

[SimonSapin]

Description

The conversion of StringValue to String is incorrect when the value ends with an escaped double-quote \". There is likely a similar bug with block strings that end with \""" or starts with " but it is masked by #609. The offending code removes any number of " characters here:

apollo-rs/crates/apollo-parser/src/ast/node_ext.rs

Line 201 in 126816f

unescape_string(text.trim_start_matches('"').trim_end_matches('"'))

Steps to reproduce

crates/apollo-parser/src/ast/node_ext.rs

#[cfg(test)]
mod tests {
    use crate::ast;
    use crate::Parser;

    #[test]
    fn test_tailing_escaped_quote() {
        let input = r#"
            query ($arg: Int!) {
                field(
                    string: "a\""
                )
            }
        "#;
        let values = extract_argument_values(input);
        let ast::Value::StringValue(block_string) = &values[0] else { panic!() };
        assert_eq!(String::try_from(block_string).as_deref(), Ok(r#"a""#));
    }

    fn extract_argument_values(input: &str) -> Vec<ast::Value> {
        let ast = Parser::new(input).parse();
        assert_eq!(ast.errors().as_slice(), []);
        let ast::Definition::OperationDefinition(operation) = ast
            .document()
            .definitions()
            .next()
            .unwrap()
        else { panic!("expected an operation") };
        let ast::Selection::Field(field) = operation
            .selection_set()
            .unwrap()
            .selections()
            .next()
            .unwrap()
        else { panic!("expected a field") };
        field
            .arguments()
            .unwrap()
            .arguments()
            .map(|arg| arg.value().unwrap())
            .collect()
    }
}

Expected result

Test passes

Actual result

thread 'ast::node_ext::tests::test_tailing_escaped_quote' panicked at 'assertion failed: `(left == right)`
  left: `Ok("a\\")`,
 right: `Ok("a\"")`', crates/apollo-parser/src/ast/node_ext.rs:301:9

Environment

• apollo-rs crate: apollo-parser
• Crate version: either 0.5.3 or main 126816f