xorshift64star_test.gno

  1package xorshift64star
  2
  3import (
  4	"math/rand"
  5	"testing"
  6)
  7
  8func TestXorshift64StarSeeding(t *testing.T) {
  9	rnd := New()
 10	value1 := rnd.Uint64()
 11
 12	rnd = New(987654321)
 13	value2 := rnd.Uint64()
 14
 15	if value1 != 3506338452768534464 || value2 != 18211065302896784785 || value1 == value2 {
 16		t.Errorf("Expected 2 different values; got: %d and %d", value1, value2)
 17	}
 18}
 19
 20func TestXorshift64StarRand(t *testing.T) {
 21	rnd := New(987654321)
 22	rng := rand.New(rnd)
 23
 24	// Expected outputs for the first 5 random floats with the given seed
 25	expected := []float64{
 26		.8344002228310946,
 27		0.01777174153236205,
 28		0.23521769507865276,
 29		0.5387610198576143,
 30		0.631539862225968,
 31		0.9369068148346704,
 32		0.6387002315083188,
 33		0.5047507613688854,
 34		0.5208486273732391,
 35		0.25023746271541747,
 36	}
 37
 38	for i, exp := range expected {
 39		val := rng.Float64()
 40		if exp != val {
 41			t.Errorf("Rand.Float64() at iteration %d: got %g, expected %g", i, val, exp)
 42		}
 43	}
 44}
 45
 46func TestXorshift64StarUint64(t *testing.T) {
 47	rnd := New(1000)
 48
 49	expected := []uint64{
 50		12487186097140327178,
 51		14661465266242046735,
 52		14694269887751719025,
 53		15763651124252725051,
 54		6358063137690011177,
 55		16123467710013993794,
 56		8086526499083208127,
 57		5907916440057635441,
 58		7074828965897564835,
 59		219959441764368518,
 60	}
 61
 62	for i, exp := range expected {
 63		val := rnd.Uint64()
 64		if exp != val {
 65			t.Errorf("Xorshift64Star.Uint64() at iteration %d: got %d, expected %d", i, val, exp)
 66		}
 67	}
 68}
 69
 70func TestXorshift64StarMarshalUnmarshal(t *testing.T) {
 71	rnd := New(1001)
 72
 73	expected1 := []uint64{
 74		17667678392346722343,
 75		8998941448230025236,
 76		6038719778092581458,
 77		9916057400810746083,
 78		3240504040424884895,
 79	}
 80
 81	expected2 := []uint64{
 82		3977048231667561376,
 83		18438555156602529247,
 84		2172795924893074637,
 85		12043507788481457357,
 86		8032279100325099159,
 87	}
 88
 89	for i, exp := range expected1 {
 90		val := rnd.Uint64()
 91		if exp != val {
 92			t.Errorf("Xorshift64Star.Uint64() at iteration %d: got %d, expected %d", i, val, exp)
 93		}
 94	}
 95
 96	marshalled, err := rnd.MarshalBinary()
 97
 98	// t.Logf("Original State: [%x]\n", rnd.seed)
 99	// t.Logf("Marshalled State: [%x] -- %v\n", marshalled, err)
100	state_before := rnd.seed
101
102	if err != nil {
103		t.Errorf("Xorshift64Star.MarshalBinary() error: %v", err)
104	}
105
106	// Advance state by one number; then check the next 5. The expectation is that they _will_ fail.
107	rnd.Uint64()
108
109	for i, exp := range expected2 {
110		val := rnd.Uint64()
111		if exp == val {
112			t.Errorf("  Iteration %d matched %d; which is from iteration %d; something strange is happening.", (i + 6), val, (i + 5))
113		}
114	}
115
116	// t.Logf("State before unmarshall: [%x]\n", rnd.seed)
117
118	// Now restore the state of the PRNG
119	err = rnd.UnmarshalBinary(marshalled)
120
121	// t.Logf("State after unmarshall: [%x]\n", rnd.seed)
122
123	if state_before != rnd.seed {
124		t.Errorf("States before and after marshal/unmarshal are not equal; go %x and %x", state_before, rnd.seed)
125	}
126
127	// Now we should be back on track for the last 5 numbers
128	for i, exp := range expected2 {
129		val := rnd.Uint64()
130		if exp != val {
131			t.Errorf("Xorshift64Star.Uint64() at iteration %d: got %d, expected %d", (i + 5), val, exp)
132		}
133	}
134}