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Rust FFI Testing Strategy

Practical ffi guide for Rust/C boundary correctness with runnable examples and review-ready checklists.

Topic: FFI

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Rust FFI Testing Strategy

Problem

Teams often struggle with Rust/C boundary correctness when code grows quickly and review cycles shorten. This guide turns that into a repeatable process.

Diagnostic checklist

  • Define one concrete failure mode before changing code.
  • Reduce to a minimal example first.
  • Validate assumptions around ownership, mutability, and API boundaries.
  • Keep fix scope small and testable.

Runnable example

rust
fn main() {
    let data = vec![1, 2, 3, 4];
    let sum: i32 = data.iter().sum();
    println!("sum={}", sum);
}

Counterexample

rust
fn main() {
    let s = String::from("hello");
    let moved = s;
    println!("{}", s); // moved value
}

How to decide in production

1. Start with correctness and explicit ownership.

2. Add instrumentation before optimizing.

3. Keep interfaces small and typed.

4. Record tradeoffs directly in code and PR description.

Related reading

Related Guides

Rust FFI Debug Checklist

Practical ffi guide for Rust/C boundary correctness with runnable examples and review-ready checklists.

Rust FFI Production Guide

Practical ffi guide for Rust/C boundary correctness with runnable examples and review-ready checklists.

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