prng_test.go

package qrprng_test

import (
	"testing"

	"github.com/mattwiller/qrprng"
	"github.com/stretchr/testify/assert"
)

func TestPermutationTrivial(t *testing.T) {
	testPermutation(t, 11, 0, 0)
}

func TestPermutationTiny(t *testing.T) {
	testPermutation(t, 83, 72, 0)
}

func TestPermutationSmall(t *testing.T) {
	testPermutation(t, 727, 253, 0)
}

func TestFullExample(t *testing.T) {
	prime := uint64(727)
	rng, err := qrprng.New(prime, 253, 0)
	// expected mask: 471, maxMask: 511
	assert.NoError(t, err)

	expected := []uint64{110, 242, 722, 61, 269, 172, 175, 206, 231, 145, 409, 476, 103, 410, 484, 81, 310, 671, 37, 317, 340, 365, 22, 59, 77, 620, 528, 376, 462, 414, 358, 123, 659, 542, 156, 96, 460, 165, 205, 264, 474, 117, 3, 302, 291, 84, 182, 270, 91, 196, 693, 719, 79, 385, 480, 326, 8, 486, 403, 378, 388, 703, 625, 29, 558, 373, 66, 161, 130, 191, 107, 281, 419, 456, 428, 62, 407, 56, 457, 507, 355, 128, 23, 337, 437, 104, 504, 636, 621, 212, 53, 250, 678, 224, 427, 605, 532, 716, 590, 618, 374, 221, 64, 332, 489, 72, 634, 593, 92, 362, 691, 106, 685, 266, 473, 301, 89, 644, 73, 118, 31, 46, 548, 261, 98, 357, 211, 346, 214, 335, 431, 298, 580, 341, 541, 436, 582, 351, 467, 610, 30, 662, 537, 252, 615, 568, 220, 78, 698, 381, 14, 247, 342, 651, 243, 15, 80, 533, 569, 82, 425, 320, 233, 614, 453, 633, 314, 553, 148, 676, 176, 240, 527, 155, 702, 93, 430, 690, 307, 97, 518, 255, 137, 479, 35, 186, 699, 669, 51, 321, 530, 299, 599, 609, 39, 169, 392, 115, 557, 287, 706, 271, 535, 675, 101, 640, 550, 306, 296, 190, 421, 109, 20, 674, 207, 408, 547, 125, 141, 708, 499, 126, 664, 681, 132, 583, 492, 503, 183, 594, 622, 313, 514, 352, 420, 244, 554, 32, 194, 154, 139, 363, 189, 95, 389, 393, 589, 394, 10, 57, 87, 217, 395, 416, 277, 160, 442, 134, 600, 441, 63, 360, 129, 423, 577, 500, 86, 322, 116, 601, 324, 418, 672, 377, 529, 561, 402, 143, 144, 556, 364, 613, 555, 397, 197, 552, 501, 0, 26, 203, 333, 369, 114, 700, 202, 171, 574, 228, 448, 71, 282, 286, 58, 2, 440, 433, 446, 663, 140, 717, 181, 177, 238, 564, 198, 626, 227, 348, 526, 163, 210, 283, 151, 396, 300, 576, 513, 665, 650, 273, 215, 630, 725, 76, 336, 44, 49, 113, 68, 639, 174, 619, 239, 602, 12, 323, 187, 327, 204, 546, 259, 406, 572, 318, 635, 482, 692, 100, 36, 256, 638, 468, 153, 549, 667, 517, 193, 27, 565, 166, 339, 405, 726, 366, 660, 641, 45, 38, 308, 519, 311, 573, 234, 603, 122, 50, 162, 643, 375, 368, 661, 458, 531, 632, 24, 168, 4, 262, 567, 575, 222, 697, 21, 229, 588, 449, 120, 131, 343, 292, 150, 711, 178, 54, 344, 380, 631, 483, 521, 704, 432, 679, 497, 515, 152, 40, 712, 538, 673, 562, 248, 138, 9, 658, 188, 560, 235, 319, 508, 545, 88, 379, 361, 648, 157, 670, 213, 657, 372, 713, 475, 536, 353, 496, 383, 185, 653, 316, 677, 399, 510, 170, 315, 142, 450, 99, 1, 293, 701, 275, 477, 288, 328, 689, 43, 723, 429, 612, 434, 680, 415, 656, 481, 345, 216, 463, 34, 83, 655, 444, 312, 596, 683, 505, 209, 354, 85, 135, 511, 90, 179, 359, 666, 512, 581, 721, 485, 401, 278, 471, 370, 274, 566, 295, 417, 598, 19, 498, 52, 616, 540, 438, 652, 470, 523, 435, 330, 551, 624, 367, 102, 263, 714, 637, 570, 25, 617, 297, 447, 506, 254, 258, 195, 251, 445, 382, 611, 164, 218, 180, 539, 629, 455, 146, 7, 121, 280, 226, 595, 208, 627, 94, 487, 424, 347, 272, 28, 232, 111, 623, 391, 260, 578, 384, 41, 387, 606, 411, 585, 715, 289, 159, 13, 592, 413, 331, 108, 586, 70, 509, 682, 465, 686, 225, 472, 559, 654, 276, 452, 133, 591, 724, 607, 60, 584, 443, 267, 112, 426, 524, 469, 124, 147, 390, 69, 439, 649, 303, 11, 237, 350, 459, 105, 647, 304, 684, 696, 587, 42, 522, 167, 334, 604, 488, 563, 5, 493, 534, 246, 571, 65, 520, 33, 16, 75, 74, 257, 284, 223, 502, 454, 404, 544, 219, 694, 645, 705, 249, 494, 646, 398, 597, 18, 356, 709, 309, 525, 668, 461, 230, 253, 294, 338, 495, 47, 173, 464, 6, 265, 688, 136, 491, 268, 642, 192, 386, 490, 608, 543, 371, 241, 687, 628, 285, 478, 245, 710, 516, 422, 17, 579, 290, 412, 127, 400, 67, 279, 201, 695, 48, 158, 718, 149, 236, 720, 199, 55, 325, 305, 184, 119, 200, 466, 451, 349, 329, 707}
	for i := uint64(0); i < prime; i++ {
		n, err := rng.Index(i)
		assert.NoError(t, err)
		assert.Equal(t, expected[i], n, "Sequence permutation diverged at index %d: expected %d / got %d", i, expected[i], n)
	}
}

func TestPermutationMedium(t *testing.T) {
	testPermutation(t, 11_587, 1234, 0)
}

func testPermutation(t *testing.T, prime, intermediateOffset, offset uint64) {
	t.Helper()

	rng, err := qrprng.New(prime, intermediateOffset, offset)
	assert.NoError(t, err)

	seen := make(map[uint64]struct{}, prime-1)
	for i := uint64(0); i < prime; i++ {
		n, err := rng.Index(i)
		assert.NoError(t, err)
		seen[n] = struct{}{}
	}

	for i := uint64(0); i < prime; i++ {
		assert.Contains(t, seen, i, "Expected sequence to contain permuted element: %d", i)
	}
}