diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/math/big/int.go | 5 | ||||
| -rw-r--r-- | src/math/big/int_test.go | 15 |
2 files changed, 19 insertions, 1 deletions
diff --git a/src/math/big/int.go b/src/math/big/int.go index d22e39e7c9..b6c7070d9d 100644 --- a/src/math/big/int.go +++ b/src/math/big/int.go @@ -736,8 +736,11 @@ func (z *Int) binaryGCD(a, b *Int) *Int { // ProbablyPrime performs n Miller-Rabin tests to check whether x is prime. // If it returns true, x is prime with probability 1 - 1/4^n. -// If it returns false, x is not prime. +// If it returns false, x is not prime. n must be >0. func (x *Int) ProbablyPrime(n int) bool { + if n <= 0 { + panic("non-positive n for ProbablyPrime") + } return !x.neg && x.abs.probablyPrime(n) } diff --git a/src/math/big/int_test.go b/src/math/big/int_test.go index 6070cf325d..af3af910e9 100644 --- a/src/math/big/int_test.go +++ b/src/math/big/int_test.go @@ -989,6 +989,21 @@ func TestProbablyPrime(t *testing.T) { break } } + + // check that ProbablyPrime panics if n <= 0 + c := NewInt(11) // a prime + for _, n := range []int{-1, 0, 1} { + func() { + defer func() { + if n <= 0 && recover() == nil { + t.Fatalf("expected panic from ProbablyPrime(%d)", n) + } + }() + if !c.ProbablyPrime(n) { + t.Fatalf("%v should be a prime", c) + } + }() + } } type intShiftTest struct { |