libgo/go/crypto/rand/util_test.go

   1 // Copyright 2013 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
   5 package rand_test
   6
   7 import (
   8         "crypto/rand"
   9         "math/big"
  10         "testing"
  11 )
  12
  13 // http://golang.org/issue/6849.
  14 func TestPrimeSmall(t *testing.T) {
  15         for n := 2; n < 10; n++ {
  16                 p, err := rand.Prime(rand.Reader, n)
  17                 if err != nil {
  18                         t.Fatalf("Can't generate %d-bit prime: %v", n, err)
  19                 }
  20                 if p.BitLen() != n {
  21                         t.Fatalf("%v is not %d-bit", p, n)
  22                 }
  23                 if !p.ProbablyPrime(32) {
  24                         t.Fatalf("%v is not prime", p)
  25                 }
  26         }
  27 }
  28
  29 // Test that passing bits < 2 causes Prime to return nil, error
  30 func TestPrimeBitsLt2(t *testing.T) {
  31         if p, err := rand.Prime(rand.Reader, 1); p != nil || err == nil {
  32                 t.Errorf("Prime should return nil, error when called with bits < 2")
  33         }
  34 }
  35
  36 func TestInt(t *testing.T) {
  37         // start at 128 so the case of (max.BitLen() % 8) == 0 is covered
  38         for n := 128; n < 140; n++ {
  39                 b := new(big.Int).SetInt64(int64(n))
  40                 if i, err := rand.Int(rand.Reader, b); err != nil {
  41                         t.Fatalf("Can't generate random value: %v, %v", i, err)
  42                 }
  43         }
  44 }
  45
  46 func testIntPanics(t *testing.T, b *big.Int) {
  47         defer func() {
  48                 if err := recover(); err == nil {
  49                         t.Errorf("Int should panic when called with max <= 0: %v", b)
  50                 }
  51         }()
  52         rand.Int(rand.Reader, b)
  53 }
  54
  55 // Test that passing a new big.Int as max causes Int to panic
  56 func TestIntEmptyMaxPanics(t *testing.T) {
  57         b := new(big.Int)
  58         testIntPanics(t, b)
  59 }
  60
  61 // Test that passing a negative value as max causes Int to panic
  62 func TestIntNegativeMaxPanics(t *testing.T) {
  63         b := new(big.Int).SetInt64(int64(-1))
  64         testIntPanics(t, b)
  65 }