sieve_test.gno

 1package sieve
 2
 3import (
 4	"testing"
 5
 6	"gno.land/p/nt/uassert/v0"
 7)
 8
 9func TestPrimesUpTo(t *testing.T) {
10	cases := []struct {
11		name string
12		n    int
13		want []int
14	}{
15		{"below two", 1, []int{}},
16		{"exactly two", 2, []int{2}},
17		{"ten", 10, []int{2, 3, 5, 7}},
18		{"thirty", 30, []int{2, 3, 5, 7, 11, 13, 17, 19, 23, 29}},
19	}
20
21	for _, tc := range cases {
22		got := PrimesUpTo(tc.n)
23		uassert.Equal(t, len(tc.want), len(got), tc.name+": length")
24		for i := range tc.want {
25			if i >= len(got) {
26				break
27			}
28			uassert.Equal(t, tc.want[i], got[i], tc.name+": element")
29		}
30	}
31
32	// π(100) == 25, π(1000) == 168 — classic sieve landmarks.
33	uassert.Equal(t, 25, len(PrimesUpTo(100)), "pi(100)")
34	uassert.Equal(t, 168, len(PrimesUpTo(1000)), "pi(1000)")
35
36	// clamping: anything above MaxN yields the same set as MaxN.
37	uassert.Equal(t, len(PrimesUpTo(MaxN)), len(PrimesUpTo(MaxN+5000)), "clamp")
38}
39
40func TestIsPrimeAndNthPrime(t *testing.T) {
41	primeCases := []int{2, 3, 5, 7, 11, 13, 9973}
42	for _, p := range primeCases {
43		uassert.True(t, IsPrime(p), "expected prime")
44	}
45
46	compositeCases := []int{0, 1, 4, 9, 100, 9975}
47	for _, c := range compositeCases {
48		uassert.False(t, IsPrime(c), "expected non-prime")
49	}
50
51	uassert.Equal(t, 2, NthPrime(1), "1st prime")
52	uassert.Equal(t, 29, NthPrime(10), "10th prime")
53	uassert.Equal(t, 541, NthPrime(100), "100th prime")
54	uassert.Equal(t, 0, NthPrime(0), "0th prime is invalid")
55}