You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: no_undefined_variables.rs
    path of file: ./repos/grafbase/engine/crates/engine/src/validation/rules
    
    the code of the file until where you have to start completion: use std::collections::{HashMap, HashSet};

use engine_value::Value;

use crate::{
    parser::types::{ExecutableDocument, FragmentDefinition, FragmentSpread, OperationDefinition, VariableDefinition},
    validation::{
        utils::{referenced_variables, Scope},
        visitor::{Visitor, VisitorContext},
    },
    Name, Pos, Positioned,
};

#[derive(Default)]
pub struct NoUnde
    
    fn multiple_variables_in_fragments_not_defined() {
        expect_fails_rule!(
            factory,
            r"
          query Foo($b: String) {
            ...FragA
          }
          fragment FragA on Type {
            field(a: $a) {
              ...FragB
            }
          }
          fragment FragB on Type {
            field(b: $b) {
              ...FragC
            }
          }
          fragment FragC on Type {
            field(c: $c)
          }
        ",
        );
    }