Crate chaos_theory 

chaos_theory is a modern 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.

Quickstart

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.

Highlights

• 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

Documentation

• Guide
• FAQ
• Changelog

Modules

_docs

Additional documentation.

_examples

Complete examples.

make

Collection of built-in generator implementations.

Macros

assume

Mark the current test case as invalid if the expression is false.

fuzz_target_libfuzzer

Define a libfuzzer_sys fuzz target compatible with cargo-fuzz.

vdbg

dbg wrapper that only outputs values for visible test case runs.

veprintln

eprintln wrapper that only outputs values for visible test case runs.

vprintln

println wrapper that only outputs values for visible test case runs.

Structs

Config

Builder for a customized Env.

Env

Structural pseudo-random generation and property-checking environment.

Gen

Type-erased generator of T, implemented as a boxed trait object.

GenShared

Thread-safe type-erased generator of T, implemented as a boxed trait object.

Source

Primary interface for working with pseudo-random data and control flow.

SourceEx

Lower-level variant of Source with explicit example threading and structural control.

Enums

Effect

Result of the Source::repeat or SourceEx::repeat step.

MaybeOwned

Type that represents either owned or borrowed values.

Traits

Arbitrary

A trait for types that have a default Generator implementation.

Generator

A trait for types that describe composable generation of values.

OptionExt

Utility trait to give Option an OptionExt::assume_some helper.

Functions

checkstd

Check that property holds (does not panic).

should_log

Determine whether debug output should be emitted for the current test-case run.

Derive Macros

Arbitraryderive

Derives an implementation of chaos_theory::Arbitrary.