chaos_theory

chaos_theory is a modern Rust property-based testing and structure-aware fuzzing library.

You drive tests using Source to get structured pseudo-random values and control flow, chaos_theory ensures that this exploration is efficient and any failures found are automatically minimized.

use chaos_theory::check;

#[test]
fn sort_strings() {
    check(|src| {
        let mut strings: Vec<String> = src.any("strings");
        strings.sort();
        assert!(strings.is_sorted(), "unsorted after sort: {strings:?}");
    });
}

More complete examples:

• parse_date function test
• Queue state machine test

When a failure happens, chaos_theory prints a CHAOS_THEORY_REPLAY=... string you can use to reproduce the case.

• Property testing and structure-aware fuzzing in one library
• Efficient state space exploration:
  • bias towards small values and edge cases
  • structural mutations and crossover
  • example-guided generation
  • built-in swarm testing
• Macro-free, immediate-mode API: generate values and control flow as the test runs
• Zero unsafe code, zero required dependencies and no_std-compatible

• API reference
• Guide
• FAQ
• Changelog

Beta – chaos_theory works well and is useful, but does not guarantee API stability.

Notable gaps:

• Proper recursive generators

• Feedback – bug reports, issues, proposals – is welcome
• Pull requests require prior discussion before being open
• All AI usage must be disclosed

MPL-2.0, see LICENSE.