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export const description = `
Unittests for the pseudo random number generator
`;
import { makeTestGroup } from '../common/framework/test_group.js';
import { fullU32Range } from '../webgpu/util/math.js';
import { PRNG } from '../webgpu/util/prng.js';
import { UnitTest } from './unit_test.js';
export const g = makeTestGroup(UnitTest);
// There exist more formal tests for the quality of random number generators
// that are out of the scope for testing here (and are checked against the
// original C implementation).
// These tests are just intended to be smoke tests for implementation.
// Test against the reference u32 values from the original C implementation
// https://github.com/MersenneTwister-Lab/TinyMT/blob/master/tinymt/check32.out.txt
g.test('check').fn(t => {
const p = new PRNG(1);
// prettier-ignore
const expected = [
2545341989, 981918433, 3715302833, 2387538352, 3591001365,
3820442102, 2114400566, 2196103051, 2783359912, 764534509,
643179475, 1822416315, 881558334, 4207026366, 3690273640,
3240535687, 2921447122, 3984931427, 4092394160, 44209675,
2188315343, 2908663843, 1834519336, 3774670961, 3019990707,
4065554902, 1239765502, 4035716197, 3412127188, 552822483,
161364450, 353727785, 140085994, 149132008, 2547770827,
4064042525, 4078297538, 2057335507, 622384752, 2041665899,
2193913817, 1080849512, 33160901, 662956935, 642999063,
3384709977, 1723175122, 3866752252, 521822317, 2292524454,
];
expected.forEach((_, i) => {
const val = p.randomU32();
t.expect(
val === expected[i],
`PRNG(1) failed produced the ${i}th expected item, ${val} instead of ${expected[i]})`
);
});
});
// Prove that generator is deterministic for at least 1000 values with different
// seeds.
g.test('deterministic_random').fn(t => {
fullU32Range().forEach(seed => {
const lhs = new PRNG(seed);
const rhs = new PRNG(seed);
for (let i = 0; i < 1000; i++) {
const lhs_val = lhs.random();
const rhs_val = rhs.random();
t.expect(
lhs_val === rhs_val,
`For seed ${seed}, the ${i}th item, PRNG was non-deterministic (${lhs_val} vs ${rhs_val})`
);
}
});
});
g.test('deterministic_randomU32').fn(t => {
fullU32Range().forEach(seed => {
const lhs = new PRNG(seed);
const rhs = new PRNG(seed);
for (let i = 0; i < 1000; i++) {
const lhs_val = lhs.randomU32();
const rhs_val = rhs.randomU32();
t.expect(
lhs_val === rhs_val,
`For seed ${seed}, the ${i}th item, PRNG was non-deterministic (${lhs_val} vs ${rhs_val})`
);
}
});
});
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