property_testing

property_testing

The property_testing module is a small QuickCheck/Hypothesis-style property-based testing framework. You define a generator that produces random inputs and a property predicate that should hold for all inputs; the module runs the predicate against many random inputs and reports any counterexample.

Import

use std::core::utils::property_testing

Running Properties

property_testing::property(name: string, n_trials: int, gen_fn, prop_fn)

Run a single property. gen_fn() -> input generates a random input; prop_fn(input) -> bool checks the property. Stops on the first failure.

Returns { passed: bool, name: string, trials: int, counterexample: _? }.

use std::core::utils::property_testing

let result = property_testing::property(
    "abs is non-negative",
    100,
    property_testing::gen_int(-1000, 1000),
    |x| abs(x) >= 0
)
print(f"{result.name}: {if result.passed { \"PASS\" } else { \"FAIL\" }}")

property_testing::run_properties(tests)

Run multiple properties and return a summary. Each test is { name, trials, gen, prop }.

let summary = property_testing::run_properties([
    {
        name: "addition is commutative",
        trials: 200,
        gen: property_testing::gen_int(-100, 100),
        prop: |x| {
            let y = 7
            (x + y) == (y + x)
        }
    }
])
print(f"passed: {summary.passed}/{summary.total}")

Built-in Generators

These return generator closures () -> value.

Generator	Description
gen_int(lo, hi)	Random int in [lo, hi]
gen_float(lo, hi)	Random float in [lo, hi)
gen_bool()	Random boolean
gen_string(max_len)	Random ASCII alphanumeric string of length [0, max_len]
gen_array(max_len, elem_gen)	Random array of length [0, max_len] from elem_gen
gen_one_of(choices)	Pick one value uniformly at random

use std::core::utils::property_testing

let int_gen = property_testing::gen_int(0, 100)
let arr_gen = property_testing::gen_array(10, int_gen)

let result = property_testing::property(
    "len is non-negative",
    50,
    arr_gen,
    |arr| arr.length >= 0
)

See Also

• testing — single-assertion unit tests