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// Copyright ©2020 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package testrand provides random generation and flags for testing.
package testrand
import (
"flag"
"golang.org/x/exp/rand"
)
var (
seedFlag = flag.Uint64("testrand.seed", 1, "random seed for tests (0=randomize)")
extremeFlag = flag.Float64("testrand.extreme", 0, "probability of returning extreme values")
nanFlag = flag.Float64("testrand.nan", 0, "probability of returning nan")
)
// TB is an interface that corresponds to a subset of *testing.T and *testing.B.
type TB interface {
Logf(format string, args ...interface{})
}
// Source corresponds to the interface in golang.org/x/exp/rand.Source.
type Source = rand.Source
// Rand corresponds to golang.org/x/exp/rand.Rand.
type Rand interface {
ExpFloat64() float64
Float32() float32
Float64() float64
Int() int
Int31() int32
Int31n(n int32) int32
Int63() int64
Int63n(n int64) int64
Intn(n int) int
NormFloat64() float64
Perm(n int) []int
Read(p []byte) (n int, err error)
Seed(seed uint64)
Shuffle(n int, swap func(i, j int))
Uint32() uint32
Uint64() uint64
Uint64n(n uint64) uint64
}
// New returns a new random number generator using the global flags.
func New(tb TB) Rand {
seed := *seedFlag
if seed == 0 {
seed = rand.Uint64()
}
// Don't log the default case.
if seed == 1 && *extremeFlag == 0 && *nanFlag == 0 {
base := rand.New(rand.NewSource(seed))
return base
}
tb.Logf("seed=%d, prob=%.2f, nan=%.2f", seed, *extremeFlag, *nanFlag)
base := rand.New(rand.NewSource(seed))
if *extremeFlag <= 0 && *nanFlag <= 0 {
return base
}
return newExtreme(*extremeFlag, *nanFlag, base)
}
// NewSource returns a new source for random numbers.
func NewSource(tb TB) Source {
seed := *seedFlag
if seed == 0 {
seed = rand.Uint64()
}
// Don't log the default case.
if seed == 1 {
return rand.NewSource(seed)
}
tb.Logf("seed %d", seed)
return rand.NewSource(seed)
}
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