package captcha

import "testing"

func TestPrngKnownVectors(t *testing.T) {
	cases := []struct {
		seed   string
		length int
		want   string
	}{
		{"hello", 8, "eb492c6e"},
		{"hello", 16, "eb492c6e1655ea8c"},
		{"test", 32, "9c7ca3730a4a283aa6e4bc1c1d83b14f"},
		{"a", 8, "441aaeb8"},
		{"z", 8, "da40eb31"},
	}
	for _, c := range cases {
		if got := prng(c.seed, c.length); got != c.want {
			t.Errorf("prng(%q,%d)=%q want %q", c.seed, c.length, got, c.want)
		}
	}
}

func TestPrngLengthAndDeterminism(t *testing.T) {
	for _, n := range []int{1, 8, 16, 32, 64} {
		if got := prng("x", n); len(got) != n {
			t.Errorf("len(prng(\"x\",%d))=%d want %d", n, len(got), n)
		}
	}
	if prng("seed1", 16) == prng("seed2", 16) {
		t.Error("different seeds produced identical output")
	}
	a, b := prng("test", 16), prng("test", 16)
	if a != b {
		t.Error("prng not deterministic")
	}
}