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: ffi_tests.rs
    path of file: ./repos/ferrocarril/mruby-sys/src
    
    the code of the file until where you have to start completion: #![allow(non_snake_case)]
#![allow(non_upper_case_globals)]
// Tests derived from mrusty @ 1.0.0
// <https://github.com/anima-engine/mrusty/tree/v1.0.0>

// mrusty. mruby safe bindings for Rust
// Copyright (C) 2016  Drago»ô Tiselice
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

//! The tests for crate `mruby-sys` defined in this module serve as an
//! implementation gui
    
fn define_class_and_instance_method_with_one_rust_function() {
    unsafe {
        extern "C" fn rust__mruby__test_class__method__value(
            _mrb: *mut mrb_state,
            slf: mrb_value,
        ) -> mrb_value {
            unsafe {
                match slf.tt {
                    mrb_vtype::MRB_TT_OBJECT => mrb_sys_fixnum_value(2),
                    mrb_vtype::MRB_TT_CLASS => mrb_sys_fixnum_value(3),
                    tt => unreachable!("unexpected mrb_value type: {:?}", tt),
                }
            }
        }

        let mrb = mrb_open();
        let context = mrbc_context_new(mrb);

        let obj_str = CString::new("Object").unwrap();
        let obj_class = mrb_class_get(mrb, obj_str.as_ptr());
        let new_class_str = CString::new("TestClass").unwrap();
        let new_class = mrb_define_class(mrb, new_class_str.as_ptr(), obj_class);

        let rust__mruby__test_class__class_method__value = rust__mruby__test_class__method__value;

        let new_method_str = CString::new("value").unwrap();
        let new_class_method_str = CString::new("value").unwrap();

        mrb_define_method(
            mrb,
            new_class,
            new_method_str.as_ptr(),
            Some(rust__mruby__test_class__method__value),
            0,
        );
        mrb_define_class_method(
            mrb,
            new_class,
            new_class_method_str.as_ptr(),
            Some(rust__mruby__test_class__class_method__value),
            0,
        );

        let code = "TestClass.value + TestClass.new.value";
        let result = mrb_load_nstring_cxt(mrb, code.as_ptr() as *const i8, code.len(), context);
        assert_eq!(mrb_sys_fixnum_to_cint(result), 5);

        mrbc_context_free(mrb, context);
        mrb_close(mrb);
    }
}