1// Copyright 2022 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package rand_test 6 7import ( 8 . "math/rand/v2" 9 "testing" 10) 11 12// This test is first, in its own file with an alphabetically early name, 13// to try to make sure that it runs early. It has the best chance of 14// detecting deterministic seeding if it's the first test that runs. 15 16func TestAuto(t *testing.T) { 17 // Pull out 10 int64s from the global source 18 // and then check that they don't appear in that 19 // order in the deterministic seeded result. 20 var out []int64 21 for i := 0; i < 10; i++ { 22 out = append(out, Int64()) 23 } 24 25 // Look for out in seeded output. 26 // Strictly speaking, we should look for them in order, 27 // but this is good enough and not significantly more 28 // likely to have a false positive. 29 r := New(NewPCG(1, 0)) 30 found := 0 31 for i := 0; i < 1000; i++ { 32 x := r.Int64() 33 if x == out[found] { 34 found++ 35 if found == len(out) { 36 t.Fatalf("found unseeded output in Seed(1) output") 37 } 38 } 39 } 40} 41