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: codegen_test.rs
    path of file: ./repos/moon/nextgen/codegen/tests
    
    the code of the file until where you have to start completion: use moon_codegen::CodeGenerator;
use moon_common::Id;
use moon_config::{FilePath, GeneratorConfig, TemplateVariable};
use starbase_sandbox::{create_empty_sandbox, create_sandbox};

mod codegen {
    use super::*;

    mod create_template {
        use super::*;

        #[test]
        #[should_panic(expected = "A template with the name standard already exists")]
        fn errors_if_already_exists() {
            let sandbox 
    
            fn inherits_extended_variables() {
                let sandbox = create_sandbox("generator");

                let template = CodeGenerator::new(sandbox.path(), &GeneratorConfig::default())
                    .load_template("extends")
                    .unwrap();

                assert_eq!(
                    template.config.variables.keys().collect::<Vec<_>>(),
                    vec!["base", "c", "b", "a"]
                );

                // Test that the base vars aren't overwritten
                let result = matches!(
                    template.config.variables.get("c").unwrap(),
                    // c template is a string
                    TemplateVariable::Boolean(_)
                );

                assert!(result);
            }