shape-runtime 0.3.2

/// @module std::core::utils::property_testing
/// Property-Based Testing
///
/// Generates random inputs to test invariants (properties) that should
/// hold for all inputs. Inspired by QuickCheck/Hypothesis.

/// Run a property test with random inputs.
///
/// @param name - Test name for reporting
/// @param n_trials - Number of random inputs to try
/// @param gen_fn - Generator function () => input value
/// @param prop_fn - Property function (input) => bool
/// @returns { passed, name, trials, counterexample }
pub fn property(name, n_trials, gen_fn, prop_fn) {
    var counterexample = None;
    var passed = true;

    for i in range(0, n_trials) {
        let input = gen_fn();
        let result = prop_fn(input);
        if !result {
            counterexample = input;
            passed = false;
            break;
        }
    }

    {
        passed: passed,
        name: name,
        trials: n_trials,
        counterexample: counterexample
    }
}

/// Run multiple property tests and return a summary.
///
/// @param tests - Array of { name, trials, gen, prop } objects
/// @returns { passed, failed, results }
///
/// Note: `Array<int>` is the strict-typing-required concrete element type
/// for the empty-array accumulator (Cluster C of R8 W6 audit). The real
/// payload is the TypedObject returned by `property()`, but the strict
/// typing pass rejects anonymous typed-object and named typed-object
/// empty-array bindings at module-load time; only primitive element
/// annotations are honored. End-to-end behaviour for this function is
/// blocked by Cluster B (generic-arithmetic inference loss in `property`
/// callees) and is tracked alongside the broader pure-shape stdlib
/// inference fix follow-up.
pub fn run_properties(tests) {
    let mut results: Array<int> = [];
    var passed_count = 0;
    var failed_count = 0;

    for test in tests {
        let result = property(test.name, test.trials, test.gen, test.prop);
        results.push(result);
        if result.passed {
            passed_count = passed_count + 1;
        } else {
            failed_count = failed_count + 1;
        }
    }

    {
        passed: passed_count,
        failed: failed_count,
        total: tests.len(),
        results: results
    }
}

// ===== Built-in Generators =====

/// Generate random integer in [lo, hi]
pub fn gen_int(lo: number, hi: number) {
    || __intrinsic_random_int(lo, hi)
}

/// Generate random float in [lo, hi)
pub fn gen_float(lo: number, hi: number) {
    || {
        let r: number = __intrinsic_random();
        let span: number = hi - lo;
        lo + r * span
    }
}

/// Generate random boolean
pub fn gen_bool() {
    || {
        let r: number = __intrinsic_random();
        r < 0.5
    }
}

/// Generate random string of given length from ascii letters
pub fn gen_string(max_len: number) {
    || {
        let chars: string = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        let n: number = __intrinsic_random_int(0, max_len);
        var s: string = "";
        for i in range(0, n) {
            let idx: number = __intrinsic_random_int(0, 61);
            let ch: string = chars[idx];
            s = s + ch;
        }
        s
    }
}

/// Generate random array of given max length using element generator.
///
/// Note: strict typing requires a concrete element type for the empty-array
/// accumulator. `Array<int>` is chosen as the representative concrete element
/// (matches `gen_int`); generators returning other types are v0.3-gating until
/// generic empty-array element-type inference (Cluster C of R8 W6 audit, with
/// the broader generic-arithmetic inference loss in Cluster B) is implemented.
pub fn gen_array(max_len: number, elem_gen) {
    || {
        let n = __intrinsic_random_int(0, max_len);
        let mut arr: Array<int> = [];
        for i in range(0, n) {
            arr.push(elem_gen());
        }
        arr
    }
}

/// Generate a value picked uniformly from a list of choices
pub fn gen_one_of(choices: Array<int>) {
    || {
        let idx = __intrinsic_random_int(0, choices.len() - 1);
        choices[idx]
    }
}