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testing: add -shuffle=off|on|N to alter the execution order of tests and benchmarks

This CL adds a new flag to the testing package and the go test command
which randomizes the execution order for tests and benchmarks.
This can be useful for identifying unwanted dependencies
between test or benchmark functions.
The flag is off by default. If `-shuffle` is set to `on` then the system
clock will be used as the seed value. If `-shuffle` is set to an integer
N, then N will be used as the seed value. In both cases, the seed will
be reported for failed runs so that they can reproduced later on.

Fixes #28592

Change-Id: I62e7dfae5f63f97a0cbd7830ea844d9f7beac335
Reviewed-on: https://go-review.googlesource.com/c/go/+/310033
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Trust: Bryan C. Mills <bcmills@google.com>
This commit is contained in:
Paschalis Tsilias 2021-04-14 23:55:38 +03:00 committed by Ian Lance Taylor
parent e51246c881
commit cbb3f09047
10 changed files with 249 additions and 4 deletions

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@ -2667,6 +2667,13 @@
// the Go tree can run a sanity check but not spend time running
// exhaustive tests.
//
// -shuffle off,on,N
// Randomize the execution order of tests and benchmarks.
// It is off by default. If -shuffle is set to on, then it will seed
// the randomizer using the system clock. If -shuffle is set to an
// integer N, then N will be used as the seed value. In both cases,
// the seed will be reported for reproducibility.
//
// -timeout d
// If a test binary runs longer than duration d, panic.
// If d is 0, the timeout is disabled.

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@ -28,6 +28,7 @@ var passFlagToTest = map[string]bool{
"parallel": true,
"run": true,
"short": true,
"shuffle": true,
"timeout": true,
"trace": true,
"v": true,

View File

@ -272,6 +272,13 @@ control the execution of any test:
the Go tree can run a sanity check but not spend time running
exhaustive tests.
-shuffle off,on,N
Randomize the execution order of tests and benchmarks.
It is off by default. If -shuffle is set to on, then it will seed
the randomizer using the system clock. If -shuffle is set to an
integer N, then N will be used as the seed value. In both cases,
the seed will be reported for reproducibility.
-timeout d
If a test binary runs longer than duration d, panic.
If d is 0, the timeout is disabled.
@ -480,6 +487,7 @@ var (
testList string // -list flag
testO string // -o flag
testOutputDir = base.Cwd // -outputdir flag
testShuffle shuffleFlag // -shuffle flag
testTimeout time.Duration // -timeout flag
testV bool // -v flag
testVet = vetFlag{flags: defaultVetFlags} // -vet flag

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@ -10,6 +10,7 @@ import (
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
"time"
@ -68,6 +69,7 @@ func init() {
cf.DurationVar(&testTimeout, "timeout", 10*time.Minute, "")
cf.StringVar(&testTrace, "trace", "", "")
cf.BoolVar(&testV, "v", false, "")
cf.Var(&testShuffle, "shuffle", "")
for name, _ := range passFlagToTest {
cf.Var(cf.Lookup(name).Value, "test."+name, "")
@ -194,6 +196,41 @@ func (f *vetFlag) Set(value string) error {
return nil
}
type shuffleFlag struct {
on bool
seed *int64
}
func (f *shuffleFlag) String() string {
if !f.on {
return "off"
}
if f.seed == nil {
return "on"
}
return fmt.Sprintf("%d", *f.seed)
}
func (f *shuffleFlag) Set(value string) error {
if value == "off" {
*f = shuffleFlag{on: false}
return nil
}
if value == "on" {
*f = shuffleFlag{on: true}
return nil
}
seed, err := strconv.ParseInt(value, 10, 64)
if err != nil {
return fmt.Errorf(`-shuffle argument must be "on", "off", or an int64: %v`, err)
}
*f = shuffleFlag{on: true, seed: &seed}
return nil
}
// testFlags processes the command line, grabbing -x and -c, rewriting known flags
// to have "test" before them, and reading the command line for the test binary.
// Unfortunately for us, we need to do our own flag processing because go test

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@ -0,0 +1,148 @@
# Shuffle order of tests and benchmarks
# Run tests
go test -v foo_test.go
! stdout '-test.shuffle '
stdout '(?s)TestOne(.*)TestTwo(.*)TestThree'
go test -v -shuffle=off foo_test.go
! stdout '-test.shuffle '
stdout '(?s)TestOne(.*)TestTwo(.*)TestThree'
go test -v -shuffle=42 foo_test.go
stdout '^-test.shuffle 42'
stdout '(?s)TestThree(.*)TestOne(.*)TestTwo'
go test -v -shuffle=43 foo_test.go
stdout '^-test.shuffle 43'
stdout '(?s)TestThree(.*)TestTwo(.*)TestOne'
go test -v -shuffle=44 foo_test.go
stdout '^-test.shuffle 44'
stdout '(?s)TestOne(.*)TestThree(.*)TestTwo'
go test -v -shuffle=0 foo_test.go
stdout '^-test.shuffle 0'
stdout '(?s)TestTwo(.*)TestOne(.*)TestThree'
go test -v -shuffle -1 foo_test.go
stdout '^-test.shuffle -1'
stdout '(?s)TestThree(.*)TestOne(.*)TestTwo'
go test -v -shuffle=on foo_test.go
stdout '^-test.shuffle '
stdout '(?s)=== RUN TestOne(.*)--- PASS: TestOne'
stdout '(?s)=== RUN TestTwo(.*)--- PASS: TestTwo'
stdout '(?s)=== RUN TestThree(.*)--- PASS: TestThree'
# Run tests and benchmarks
go test -v -bench=. foo_test.go
! stdout '-test.shuffle '
stdout '(?s)TestOne(.*)TestTwo(.*)TestThree(.*)BenchmarkOne(.*)BenchmarkTwo(.*)BenchmarkThree'
go test -v -bench=. -shuffle=off foo_test.go
! stdout '-test.shuffle '
stdout '(?s)TestOne(.*)TestTwo(.*)TestThree(.*)BenchmarkOne(.*)BenchmarkTwo(.*)BenchmarkThree'
go test -v -bench=. -shuffle=42 foo_test.go
stdout '^-test.shuffle 42'
stdout '(?s)TestThree(.*)TestOne(.*)TestTwo(.*)BenchmarkThree(.*)BenchmarkOne(.*)BenchmarkTwo'
go test -v -bench=. -shuffle=43 foo_test.go
stdout '^-test.shuffle 43'
stdout '(?s)TestThree(.*)TestTwo(.*)TestOne(.*)BenchmarkThree(.*)BenchmarkOne(.*)BenchmarkTwo'
go test -v -bench=. -shuffle=44 foo_test.go
stdout '^-test.shuffle 44'
stdout '(?s)TestOne(.*)TestThree(.*)TestTwo(.*)BenchmarkTwo(.*)BenchmarkOne(.*)BenchmarkThree'
go test -v -bench=. -shuffle=0 foo_test.go
stdout '^-test.shuffle 0'
stdout '(?s)TestTwo(.*)TestOne(.*)TestThree(.*)BenchmarkThree(.*)BenchmarkOne(.*)BenchmarkTwo'
go test -v -bench=. -shuffle -1 foo_test.go
stdout '^-test.shuffle -1'
stdout '(?s)TestThree(.*)TestOne(.*)TestTwo(.*)BenchmarkOne(.*)BenchmarkThree(.*)BenchmarkTwo'
go test -v -bench=. -shuffle=on foo_test.go
stdout '^-test.shuffle '
stdout '(?s)=== RUN TestOne(.*)--- PASS: TestOne'
stdout '(?s)=== RUN TestTwo(.*)--- PASS: TestTwo'
stdout '(?s)=== RUN TestThree(.*)--- PASS: TestThree'
stdout -count=2 'BenchmarkOne'
stdout -count=2 'BenchmarkTwo'
stdout -count=2 'BenchmarkThree'
# When running go test -count=N, each of the N runs distinct runs should maintain the same
# shuffled order of these tests.
go test -v -shuffle=43 -count=4 foo_test.go
stdout '^-test.shuffle 43'
stdout '(?s)TestThree(.*)TestTwo(.*)TestOne(.*)TestThree(.*)TestTwo(.*)TestOne(.*)TestThree(.*)TestTwo(.*)TestOne(.*)TestThree(.*)TestTwo(.*)TestOne'
go test -v -bench=. -shuffle=44 -count=2 foo_test.go
stdout '^-test.shuffle 44'
stdout '(?s)TestOne(.*)TestThree(.*)TestTwo(.*)TestOne(.*)TestThree(.*)TestTwo(.*)BenchmarkTwo(.*)BenchmarkOne(.*)BenchmarkThree(.*)'
# The feature should work with test binaries as well
go test -c
exec ./m.test -test.shuffle=off
! stdout '^-test.shuffle '
exec ./m.test -test.shuffle=on
stdout '^-test.shuffle '
exec ./m.test -test.v -test.bench=. -test.shuffle=0 foo_test.go
stdout '^-test.shuffle 0'
stdout '(?s)TestTwo(.*)TestOne(.*)TestThree(.*)BenchmarkThree(.*)BenchmarkOne(.*)BenchmarkTwo'
exec ./m.test -test.v -test.bench=. -test.shuffle=123 foo_test.go
stdout '^-test.shuffle 123'
stdout '(?s)TestThree(.*)TestOne(.*)TestTwo(.*)BenchmarkThree(.*)BenchmarkTwo(.*)BenchmarkOne'
exec ./m.test -test.v -test.bench=. -test.shuffle=-1 foo_test.go
stdout '^-test.shuffle -1'
stdout '(?s)TestThree(.*)TestOne(.*)TestTwo(.*)BenchmarkOne(.*)BenchmarkThree(.*)BenchmarkTwo'
exec ./m.test -test.v -test.bench=. -test.shuffle=44 -test.count=2 foo_test.go
stdout '^-test.shuffle 44'
stdout '(?s)TestOne(.*)TestThree(.*)TestTwo(.*)TestOne(.*)TestThree(.*)TestTwo(.*)BenchmarkTwo(.*)BenchmarkOne(.*)BenchmarkThree(.*)'
# Negative testcases for invalid input
! go test -shuffle -count=2
stderr 'invalid value "-count=2" for flag -shuffle: -shuffle argument must be "on", "off", or an int64: strconv.ParseInt: parsing "-count=2": invalid syntax'
! go test -shuffle=
stderr '(?s)invalid value "" for flag -shuffle: -shuffle argument must be "on", "off", or an int64: strconv.ParseInt: parsing "": invalid syntax'
! go test -shuffle=' '
stderr '(?s)invalid value " " for flag -shuffle: -shuffle argument must be "on", "off", or an int64: strconv.ParseInt: parsing " ": invalid syntax'
! go test -shuffle=true
stderr 'invalid value "true" for flag -shuffle: -shuffle argument must be "on", "off", or an int64: strconv.ParseInt: parsing "true": invalid syntax'
! go test -shuffle='abc'
stderr 'invalid value "abc" for flag -shuffle: -shuffle argument must be "on", "off", or an int64: strconv.ParseInt: parsing "abc": invalid syntax'
-- go.mod --
module m
go 1.16
-- foo_test.go --
package foo
import "testing"
func TestOne(t *testing.T) {}
func TestTwo(t *testing.T) {}
func TestThree(t *testing.T) {}
func BenchmarkOne(b *testing.B) {}
func BenchmarkTwo(b *testing.B) {}
func BenchmarkThree(b *testing.B) {}
-- foo.go --
package foo

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@ -503,7 +503,7 @@ var depsRules = `
FMT, flag, math/rand
< testing/quick;
FMT, flag, runtime/debug, runtime/trace, internal/sysinfo
FMT, flag, runtime/debug, runtime/trace, internal/sysinfo, math/rand
< testing;
internal/testlog, runtime/pprof, regexp

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@ -0,0 +1,17 @@
// Copyright 2021 The Go 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 rand
func Int31nForTest(r *Rand, n int32) int32 {
return r.int31n(n)
}
func GetNormalDistributionParameters() (float64, [128]uint32, [128]float32, [128]float32) {
return rn, kn, wn, fn
}
func GetExponentialDistributionParameters() (float64, [256]uint32, [256]float32, [256]float32) {
return re, ke, we, fe
}

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@ -2,9 +2,10 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package rand
package rand_test
import (
. "math/rand"
"sync"
"testing"
)

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@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package rand
package rand_test
import (
"bytes"
@ -11,6 +11,7 @@ import (
"internal/testenv"
"io"
"math"
. "math/rand"
"os"
"runtime"
"testing"
@ -21,6 +22,9 @@ const (
numTestSamples = 10000
)
var rn, kn, wn, fn = GetNormalDistributionParameters()
var re, ke, we, fe = GetExponentialDistributionParameters()
type statsResults struct {
mean float64
stddev float64
@ -503,7 +507,7 @@ func TestUniformFactorial(t *testing.T) {
fn func() int
}{
{name: "Int31n", fn: func() int { return int(r.Int31n(int32(nfact))) }},
{name: "int31n", fn: func() int { return int(r.int31n(int32(nfact))) }},
{name: "int31n", fn: func() int { return int(Int31nForTest(r, int32(nfact))) }},
{name: "Perm", fn: func() int { return encodePerm(r.Perm(n)) }},
{name: "Shuffle", fn: func() int {
// Generate permutation using Shuffle.

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@ -242,6 +242,7 @@ import (
"fmt"
"internal/race"
"io"
"math/rand"
"os"
"runtime"
"runtime/debug"
@ -299,6 +300,7 @@ func Init() {
cpuListStr = flag.String("test.cpu", "", "comma-separated `list` of cpu counts to run each test with")
parallel = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "run at most `n` tests in parallel")
testlog = flag.String("test.testlogfile", "", "write test action log to `file` (for use only by cmd/go)")
shuffle = flag.String("test.shuffle", "off", "randomize the execution order of tests and benchmarks")
initBenchmarkFlags()
}
@ -325,6 +327,7 @@ var (
timeout *time.Duration
cpuListStr *string
parallel *int
shuffle *string
testlog *string
haveExamples bool // are there examples?
@ -1456,6 +1459,25 @@ func (m *M) Run() (code int) {
return
}
if *shuffle != "off" {
var n int64
var err error
if *shuffle == "on" {
n = time.Now().UnixNano()
} else {
n, err = strconv.ParseInt(*shuffle, 10, 64)
if err != nil {
fmt.Fprintln(os.Stderr, `testing: -shuffle should be "off", "on", or a valid integer:`, err)
m.exitCode = 2
return
}
}
fmt.Println("-test.shuffle", n)
rng := rand.New(rand.NewSource(n))
rng.Shuffle(len(m.tests), func(i, j int) { m.tests[i], m.tests[j] = m.tests[j], m.tests[i] })
rng.Shuffle(len(m.benchmarks), func(i, j int) { m.benchmarks[i], m.benchmarks[j] = m.benchmarks[j], m.benchmarks[i] })
}
parseCpuList()
m.before()