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internal/testenv: move helpers related to os/exec to a separate file 

(Suggested by Austin in CL 445596.)

Change-Id: Ic774d551e8085d15435ef2b3c78d0169a365ce41
Reviewed-on: https://go-review.googlesource.com/c/go/+/446642
Auto-Submit: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
This commit is contained in:
Bryan C. Mills 2022-10-31 16:42:30 -04:00 committed by Gopher Robot
parent c81c027982
commit 661e931dd1
2 changed files with 173 additions and 158 deletions
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173
src/internal/testenv/exec.go Normal file
View File

@ -0,0 +1,173 @@
// Copyright 2015 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 testenv
import (
"context"
"os"
"os/exec"
"runtime"
"strconv"
"strings"
"sync"
"testing"
"time"
)
// HasExec reports whether the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
func HasExec() bool {
switch runtime.GOOS {
case "js", "ios":
return false
}
return true
}
// MustHaveExec checks that the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExec calls t.Skip with an explanation.
func MustHaveExec(t testing.TB) {
if !HasExec() {
t.Skipf("skipping test: cannot exec subprocess on %s/%s", runtime.GOOS, runtime.GOARCH)
}
}
var execPaths sync.Map // path -> error
// MustHaveExecPath checks that the current system can start the named executable
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExecPath calls t.Skip with an explanation.
func MustHaveExecPath(t testing.TB, path string) {
MustHaveExec(t)
err, found := execPaths.Load(path)
if !found {
_, err = exec.LookPath(path)
err, _ = execPaths.LoadOrStore(path, err)
}
if err != nil {
t.Skipf("skipping test: %s: %s", path, err)
}
}
// CleanCmdEnv will fill cmd.Env with the environment, excluding certain
// variables that could modify the behavior of the Go tools such as
// GODEBUG and GOTRACEBACK.
func CleanCmdEnv(cmd *exec.Cmd) *exec.Cmd {
if cmd.Env != nil {
panic("environment already set")
}
for _, env := range os.Environ() {
// Exclude GODEBUG from the environment to prevent its output
// from breaking tests that are trying to parse other command output.
if strings.HasPrefix(env, "GODEBUG=") {
continue
}
// Exclude GOTRACEBACK for the same reason.
if strings.HasPrefix(env, "GOTRACEBACK=") {
continue
}
cmd.Env = append(cmd.Env, env)
}
return cmd
}
// CommandContext is like exec.CommandContext, but:
// - skips t if the platform does not support os/exec,
// - sends SIGQUIT (if supported by the platform) instead of SIGKILL
// in its Cancel function
// - adds a timeout (with an arbitrary grace period) before the test's deadline expires,
// - sets a WaitDelay for an arbitrary grace period,
// - fails the test if the command does not complete before the test's deadline, and
// - sets a Cleanup function that verifies that the test did not leak a subprocess.
func CommandContext(t testing.TB, ctx context.Context, name string, args ...string) *exec.Cmd {
t.Helper()
MustHaveExec(t)
var (
gracePeriod = 100 * time.Millisecond
cancel context.CancelFunc
)
if s := os.Getenv("GO_TEST_TIMEOUT_SCALE"); s != "" {
scale, err := strconv.Atoi(s)
if err != nil {
t.Fatalf("invalid GO_TEST_TIMEOUT_SCALE: %v", err)
}
gracePeriod *= time.Duration(scale)
}
if t, ok := t.(interface {
testing.TB
Deadline() (time.Time, bool)
}); ok {
if td, ok := t.Deadline(); ok {
if cd, ok := ctx.Deadline(); !ok || cd.Sub(td) > gracePeriod {
// Either ctx doesn't have a deadline, or its deadline would expire
// after (or too close before) the test has already timed out.
// Compute a new timeout that will expire before the test does so that
// we can terminate the subprocess with a more useful signal.
timeout := time.Until(td)
// If time allows, increase the termination grace period to 5% of the
// remaining time.
if gp := timeout / 20; gp > gracePeriod {
gracePeriod = gp
}
// When we run commands that execute subprocesses, we want to reserve two
// grace periods to clean up. We will send the first termination signal when
// the context expires, then wait one grace period for the process to
// produce whatever useful output it can (such as a stack trace). After the
// first grace period expires, we'll escalate to os.Kill, leaving the second
// grace period for the test function to record its output before the test
// process itself terminates.
timeout -= 2 * gracePeriod
ctx, cancel = context.WithTimeout(ctx, timeout)
t.Cleanup(cancel)
}
}
}
cmd := exec.CommandContext(ctx, name, args...)
cmd.Cancel = func() error {
if cancel != nil && ctx.Err() == context.DeadlineExceeded {
// The command timed out due to running too close to the test's deadline.
// There is no way the test did that intentionally — it's too close to the
// wire! — so mark it as a test failure. That way, if the test expects the
// command to fail for some other reason, it doesn't have to distinguish
// between that reason and a timeout.
t.Errorf("test timed out while running command: %v", cmd)
} else {
// The command is being terminated due to ctx being canceled, but
// apparently not due to an explicit test deadline that we added.
// Log that information in case it is useful for diagnosing a failure,
// but don't actually fail the test because of it.
t.Logf("%v: terminating command: %v", ctx.Err(), cmd)
}
return cmd.Process.Signal(Sigquit)
}
cmd.WaitDelay = gracePeriod
t.Cleanup(func() {
if cancel != nil {
cancel()
}
if cmd.Process != nil && cmd.ProcessState == nil {
t.Errorf("command was started, but test did not wait for it to complete: %v", cmd)
}
})
return cmd
}
// Command is like exec.Command, but applies the same changes as
// testenv.CommandContext (with a default Context).
func Command(t testing.TB, name string, args ...string) *exec.Cmd {
t.Helper()
return CommandContext(t, context.Background(), name, args...)
}

158
src/internal/testenv/testenv.go
View File

@ -11,7 +11,6 @@
package testenv
import (
"context"
"errors"
"flag"
"fmt"
@ -26,7 +25,6 @@ import (
"strings"
"sync"
"testing"
"time"
)
// Builder reports the name of the builder running this test
@ -217,16 +215,6 @@ func GoTool() (string, error) {
return goBin, nil
}
// HasExec reports whether the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
func HasExec() bool {
switch runtime.GOOS {
case "js", "ios":
return false
}
return true
}
// HasSrc reports whether the entire source tree is available under GOROOT.
func HasSrc() bool {
switch runtime.GOOS {
@ -236,33 +224,6 @@ func HasSrc() bool {
return true
}
// MustHaveExec checks that the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExec calls t.Skip with an explanation.
func MustHaveExec(t testing.TB) {
if !HasExec() {
t.Skipf("skipping test: cannot exec subprocess on %s/%s", runtime.GOOS, runtime.GOARCH)
}
}
var execPaths sync.Map // path -> error
// MustHaveExecPath checks that the current system can start the named executable
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExecPath calls t.Skip with an explanation.
func MustHaveExecPath(t testing.TB, path string) {
MustHaveExec(t)
err, found := execPaths.Load(path)
if !found {
_, err = exec.LookPath(path)
err, _ = execPaths.LoadOrStore(path, err)
}
if err != nil {
t.Skipf("skipping test: %s: %s", path, err)
}
}
// HasExternalNetwork reports whether the current system can use
// external (non-localhost) networks.
func HasExternalNetwork() bool {
@ -357,125 +318,6 @@ func SkipFlakyNet(t testing.TB) {
}
}
// CleanCmdEnv will fill cmd.Env with the environment, excluding certain
// variables that could modify the behavior of the Go tools such as
// GODEBUG and GOTRACEBACK.
func CleanCmdEnv(cmd *exec.Cmd) *exec.Cmd {
if cmd.Env != nil {
panic("environment already set")
}
for _, env := range os.Environ() {
// Exclude GODEBUG from the environment to prevent its output
// from breaking tests that are trying to parse other command output.
if strings.HasPrefix(env, "GODEBUG=") {
continue
}
// Exclude GOTRACEBACK for the same reason.
if strings.HasPrefix(env, "GOTRACEBACK=") {
continue
}
cmd.Env = append(cmd.Env, env)
}
return cmd
}
// CommandContext is like exec.CommandContext, but:
// - skips t if the platform does not support os/exec,
// - sends SIGQUIT (if supported by the platform) instead of SIGKILL
// in its Cancel function
// - adds a timeout (with an arbitrary grace period) before the test's deadline expires,
// - sets a WaitDelay for an arbitrary grace period,
// - fails the test if the command does not complete before the test's deadline, and
// - sets a Cleanup function that verifies that the test did not leak a subprocess.
func CommandContext(t testing.TB, ctx context.Context, name string, args ...string) *exec.Cmd {
t.Helper()
MustHaveExec(t)
var (
gracePeriod = 100 * time.Millisecond
cancel context.CancelFunc
)
if s := os.Getenv("GO_TEST_TIMEOUT_SCALE"); s != "" {
scale, err := strconv.Atoi(s)
if err != nil {
t.Fatalf("invalid GO_TEST_TIMEOUT_SCALE: %v", err)
}
gracePeriod *= time.Duration(scale)
}
if t, ok := t.(interface {
testing.TB
Deadline() (time.Time, bool)
}); ok {
if td, ok := t.Deadline(); ok {
if cd, ok := ctx.Deadline(); !ok || cd.Sub(td) > gracePeriod {
// Either ctx doesn't have a deadline, or its deadline would expire
// after (or too close before) the test has already timed out.
// Compute a new timeout that will expire before the test does so that
// we can terminate the subprocess with a more useful signal.
timeout := time.Until(td)
// If time allows, increase the termination grace period to 5% of the
// remaining time.
if gp := timeout / 20; gp > gracePeriod {
gracePeriod = gp
}
// When we run commands that execute subprocesses, we want to reserve two
// grace periods to clean up. We will send the first termination signal when
// the context expires, then wait one grace period for the process to
// produce whatever useful output it can (such as a stack trace). After the
// first grace period expires, we'll escalate to os.Kill, leaving the second
// grace period for the test function to record its output before the test
// process itself terminates.
timeout -= 2 * gracePeriod
ctx, cancel = context.WithTimeout(ctx, timeout)
t.Cleanup(cancel)
}
}
}
cmd := exec.CommandContext(ctx, name, args...)
cmd.Cancel = func() error {
if cancel != nil && ctx.Err() == context.DeadlineExceeded {
// The command timed out due to running too close to the test's deadline.
// There is no way the test did that intentionally — it's too close to the
// wire! — so mark it as a test failure. That way, if the test expects the
// command to fail for some other reason, it doesn't have to distinguish
// between that reason and a timeout.
t.Errorf("test timed out while running command: %v", cmd)
} else {
// The command is being terminated due to ctx being canceled, but
// apparently not due to an explicit test deadline that we added.
// Log that information in case it is useful for diagnosing a failure,
// but don't actually fail the test because of it.
t.Logf("%v: terminating command: %v", ctx.Err(), cmd)
}
return cmd.Process.Signal(Sigquit)
}
cmd.WaitDelay = gracePeriod
t.Cleanup(func() {
if cancel != nil {
cancel()
}
if cmd.Process != nil && cmd.ProcessState == nil {
t.Errorf("command was started, but test did not wait for it to complete: %v", cmd)
}
})
return cmd
}
// Command is like exec.Command, but applies the same changes as
// testenv.CommandContext (with a default Context).
func Command(t testing.TB, name string, args ...string) *exec.Cmd {
t.Helper()
return CommandContext(t, context.Background(), name, args...)
}
// CPUIsSlow reports whether the CPU running the test is suspected to be slow.
func CPUIsSlow() bool {
switch runtime.GOARCH {