multiple_choice

A Rust proc-macro library that provides an attribute macro #[triple_verify] for verifying function results through multiple executions.

Overview

The #[triple_verify] attribute macro automatically executes a function three times and compares the results:

• If all three results match, returns the result
• If two results match, returns the matching result and prints a warning
• If all three results differ, panics with a detailed error message

Features

• Easy to use: Simply add #[triple_verify] to any function
• Flexible: Works with any function that has non-mutable borrow parameters and returns a type implementing PartialEq
• Informative: Includes function name in error and warning messages for easier debugging
• Supports complex types: Works with tuples, arrays, vectors, and custom structs

Requirements

• Rust 2024 edition or later
• Functions using this macro must:
  1. Have no mutable borrow parameters
  2. Return a type that implements PartialEq (or tuples/arrays of such types)

Installation

Add this library as a dependency to your Cargo.toml:

[dependencies]
multiple_choice = { path = "../path/to/multiple_choice" }

Usage

extern crate multiple_choice;

use multiple_choice::triple_verify;

#[triple_verify]
fn add(a: i32, b: i32) -> i32 {
    a + b
}

#[triple_verify]
fn create_struct(id: i32, name: &str, value: f64) -> MyStruct {
    MyStruct {
        id,
        name: name.to_string(),
        value,
    }
}

fn main() {
    println!("Result: {}", add(2, 3));
}

Example Output

Normal case (all results match):

Result: 5

Warning case (two results match):

WARNING: Function add: Two results match, one differs
Result: 5

Panic case (all results differ):

thread 'main' panicked at src/main.rs:10:1:
Function different_value: All three results differ: 1, 2, 3

Testing

The library includes a comprehensive test project that verifies:

• Basic types (i32, bool, f64)
• Tuples (including tuples of structs)
• Arrays (including arrays of structs)
• Vectors (Vec)
• Custom structs
• Panic behavior

To run the tests:

cd test_project
cargo test

License

MIT