Proptest

Spec sheet

Purpose

Proptest is a property testing framework for Rust inspired by Python’s Hypothesis framework.Read 1 Oct 2026 · proptest-rs.github.io

Support

Bug reports and questions are welcome through the project repository, and contributors are asked to include Rust version, Proptest version, and relevant operating-system details.Read 1 Oct 2026 · github.com

Default test count

The default number of successful test cases required for a test to pass is 256.Read 1 Oct 2026 · proptest-rs.github.io

Failure minimization

When a failure is found, Proptest automatically finds a minimal test case that reproduces it.Read 1 Oct 2026 · proptest-rs.github.io

Failure persistence

Failing cases are persisted under a proptest-regressions directory and replayed in later test runs.Read 1 Oct 2026 · proptest-rs.github.io

Forking and timeouts

Optional fork and timeout features run test cases in subprocesses and limit their execution time.Read 1 Oct 2026 · proptest-rs.github.io

Generation model

Generation and shrinking are defined per value rather than per type, which enables flexible composition.Read 1 Oct 2026 · proptest-rs.github.io

Input generation

Generation and shrinking are defined per value rather than per type.Read 1 Oct 2026 · proptest-rs.github.io

Licensing

The repository contains Apache-2.0 and MIT licenses.Read 1 Oct 2026 · github.com

Maintenance model

Proptest is maintained on a volunteer basis.Read 1 Oct 2026 · github.com

Maintenance status

The crate is feature-complete and mainly receives passive maintenance.Read 1 Oct 2026 · proptest-rs.github.io

Minimal cases

When a failure is found, Proptest automatically finds the minimal test case that reproduces it.Read 1 Oct 2026 · proptest-rs.github.io

no_std limitations

The no_std build does not provide failure persistence, forking, or features depending on crates such as regex.Read 1 Oct 2026 · proptest-rs.github.io

no_std support

Proptest has partial no_std support and requires a nightly compiler with alloc or std for memory allocation.Read 1 Oct 2026 · proptest-rs.github.io

No-std limits

Failure persistence, forking, and regex support are unavailable in the no_std build.Read 1 Oct 2026 · proptest-rs.github.io

Rust version

The current minimum supported Rust version is 1.88.Read 1 Oct 2026 · github.com

State-machine testing

Proptest supports state-machine testing for systems such as database APIs and client-server interactions.Read 1 Oct 2026 · proptest-rs.github.io

Strategies

Tests can use regular expressions, integer ranges, and other Strategy expressions to generate inputs.Read 1 Oct 2026 · proptest-rs.github.io

WebAssembly

Proptest can compile for WebAssembly targets, but this support is highly experimental and has had little substantial testing.Read 1 Oct 2026 · proptest-rs.github.io

WebAssembly limits

On WebAssembly targets, numeric strategies for i128 and u128 are unavailable.Read 1 Oct 2026 · proptest-rs.github.io

Where Specifiction places it

• Property-Based Testing Tools#20 of 287.0