Property-based testing for Odin.

Write a property, draw generated inputs, and run it many times with deterministic replay and shrinking. pbt works with Odin libraries, CLI programs, HTTP services, stateful models, and Gransk-style external runners.

package cart_test

import "core:testing"

import pbt "pbt"

cart_total :: proc(qty, price_cents: int) -> int {
  return qty * price_cents
}

cart_total_is_stable :: proc(t: ^pbt.T) -> pbt.Result {
  qty := pbt.draw(t, pbt.int_range(0, 100))
  price := pbt.draw(t, pbt.int_range(0, 10_000))

  return pbt.equal(cart_total(qty, price), qty * price)
}

@(test)
test_cart_total :: proc(t: ^testing.T) {
  result := pbt.check("cart total is stable", cart_total_is_stable, {
    num_tests = 1_000,
    seed = 123,
  })
  defer pbt.destroy_check_result(&result)

  pbt.require_pass(t, result)
}

draw records the choices needed for replay and shrinking. check runs the property many times. A failing result keeps the seed, choices, shrunk case, notes, labels, and event trace needed to reproduce the failure.

• Deterministic seeds and strict replay
• Default-on shrinking from recorded choice streams
• Integer, float, bool, string, byte, UUID, email, date, identifier, CLI, URL, HTTP, JSON, array, dictionary, tuple, enum, optional, and unique generators
• Generator combinators such as map_gen, bind, one_of, frequency, sized, resize, scale, and such_that
• pass, fail, discard, error, assert, equal, and counterexample
• Notes, labels, classification, collection, and coverage requirements
• Stateful model testing
• Process, stdin, persistent line-protocol, HTTP, and statechart adapters
• JSON/text result output and Gransk runner support

For command-line or Gransk-compatible runners, collect properties and use the CLI helpers for listing, tags, replay, JSON output, exit codes, and --fail-fast:

properties := [?]pbt.Property_Case{
  {name = "cart total", property = cart_total_is_stable, tags = []string{"cart"}},
}

pbt.run_cli(properties[:], os.args[1:], {num_tests = 1_000})

Start with docs/runner-starter.md for a runner template.

• pbt/ - core package
• pbt_statechart/ - adapter helpers for statechart model tests
• examples/ - runnable runner and adapter examples
• docs/public-api.md - full API notes
• docs/gransk-runner-contract.md - machine-readable runner contract
• BENCHMARKS.md - benchmark commands and current measurements

• docs/public-api.md - API surface and design notes
• docs/gransk-runner-example.md - minimal Gransk-facing executable
• docs/external-target-examples.md - CLI argv and stdin target wrappers
• docs/http-target-runner.md - generated HTTP requests against a service
• docs/stateful-http-runner.md - CRUD-style stateful HTTP model
• docs/line-protocol-example.md - persistent subprocess target
• docs/statechart-model-example.md - statechart-backed stateful model
• docs/api-comparison.md - comparison with QuickCheck and test.check

odin test ./pbt
odin test ./pbt_statechart

odin run examples/gransk_runner -collection:pbt=. -- --list-properties
odin run examples/runner_starter -collection:pbt=.

odin run benchmarks/check_bench.odin -file -collection:pbt=. -o:speed