// Copyright 2012 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 runtime_test
import (
"bytes"
"errors"
"flag"
"fmt"
"internal/testenv"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
"strings"
"sync"
"testing"
)
var toRemove []string
func TestMain(m *testing.M) {
status := m.Run()
for _, file := range toRemove {
os.RemoveAll(file)
}
os.Exit(status)
}
var testprog struct {
sync.Mutex
dir string
target map[string]*buildexe
}
type buildexe struct {
once sync.Once
exe string
err error
}
func runTestProg(t *testing.T, binary, name string, env ...string) string {
if *flagQuick {
t.Skip("-quick")
}
testenv.MustHaveGoBuild(t)
exe, err := buildTestProg(t, binary)
if err != nil {
t.Fatal(err)
}
return runBuiltTestProg(t, exe, name, env...)
}
func runBuiltTestProg(t *testing.T, exe, name string, env ...string) string {
if *flagQuick {
t.Skip("-quick")
}
testenv.MustHaveGoBuild(t)
cmd := testenv.CleanCmdEnv(exec.Command(exe, name))
cmd.Env = append(cmd.Env, env...)
if testing.Short() {
cmd.Env = append(cmd.Env, "RUNTIME_TEST_SHORT=1")
}
out, _ := testenv.RunWithTimeout(t, cmd)
return string(out)
}
var serializeBuild = make(chan bool, 2)
func buildTestProg(t *testing.T, binary string, flags ...string) (string, error) {
if *flagQuick {
t.Skip("-quick")
}
testenv.MustHaveGoBuild(t)
testprog.Lock()
if testprog.dir == "" {
dir, err := os.MkdirTemp("", "go-build")
if err != nil {
t.Fatalf("failed to create temp directory: %v", err)
}
testprog.dir = dir
toRemove = append(toRemove, dir)
}
if testprog.target == nil {
testprog.target = make(map[string]*buildexe)
}
name := binary
if len(flags) > 0 {
name += "_" + strings.Join(flags, "_")
}
target, ok := testprog.target[name]
if !ok {
target = &buildexe{}
testprog.target[name] = target
}
dir := testprog.dir
// Unlock testprog while actually building, so that other
// tests can look up executables that were already built.
testprog.Unlock()
target.once.Do(func() {
// Only do two "go build"'s at a time,
// to keep load from getting too high.
serializeBuild <- true
defer func() { <-serializeBuild }()
// Don't get confused if testenv.GoToolPath calls t.Skip.
target.err = errors.New("building test called t.Skip")
exe := filepath.Join(dir, name+".exe")
t.Logf("running go build -o %s %s", exe, strings.Join(flags, " "))
cmd := exec.Command(testenv.GoToolPath(t), append([]string{"build", "-o", exe}, flags...)...)
cmd.Dir = "testdata/" + binary
out, err := testenv.CleanCmdEnv(cmd).CombinedOutput()
if err != nil {
target.err = fmt.Errorf("building %s %v: %v\n%s", binary, flags, err, out)
} else {
target.exe = exe
target.err = nil
}
})
return target.exe, target.err
}
func TestVDSO(t *testing.T) {
t.Parallel()
output := runTestProg(t, "testprog", "SignalInVDSO")
want := "success\n"
if output != want {
t.Fatalf("output:\n%s\n\nwanted:\n%s", output, want)
}
}
func testCrashHandler(t *testing.T, cgo bool) {
type crashTest struct {
Cgo bool
}
var output string
if cgo {
output = runTestProg(t, "testprogcgo", "Crash")
} else {
output = runTestProg(t, "testprog", "Crash")
}
want := "main: recovered done\nnew-thread: recovered done\nsecond-new-thread: recovered done\nmain-again: recovered done\n"
if output != want {
t.Fatalf("output:\n%s\n\nwanted:\n%s", output, want)
}
}
func TestCrashHandler(t *testing.T) {
testCrashHandler(t, false)
}
func testDeadlock(t *testing.T, name string) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
output := runTestProg(t, "testprog", name)
want := "fatal error: all goroutines are asleep - deadlock!\n"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestSimpleDeadlock(t *testing.T) {
testDeadlock(t, "SimpleDeadlock")
}
func TestInitDeadlock(t *testing.T) {
testDeadlock(t, "InitDeadlock")
}
func TestLockedDeadlock(t *testing.T) {
testDeadlock(t, "LockedDeadlock")
}
func TestLockedDeadlock2(t *testing.T) {
testDeadlock(t, "LockedDeadlock2")
}
func TestGoexitDeadlock(t *testing.T) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
output := runTestProg(t, "testprog", "GoexitDeadlock")
want := "no goroutines (main called runtime.Goexit) - deadlock!"
if !strings.Contains(output, want) {
t.Fatalf("output:\n%s\n\nwant output containing: %s", output, want)
}
}
func TestStackOverflow(t *testing.T) {
if runtime.Compiler == "gccgo" {
t.Skip("gccgo does not do stack overflow checking")
}
output := runTestProg(t, "testprog", "StackOverflow")
want := []string{
"runtime: goroutine stack exceeds 1474560-byte limit\n",
"fatal error: stack overflow",
// information about the current SP and stack bounds
"runtime: sp=",
"stack=[",
}
if !strings.HasPrefix(output, want[0]) {
t.Errorf("output does not start with %q", want[0])
}
for _, s := range want[1:] {
if !strings.Contains(output, s) {
t.Errorf("output does not contain %q", s)
}
}
if t.Failed() {
t.Logf("output:\n%s", output)
}
}
func TestThreadExhaustion(t *testing.T) {
output := runTestProg(t, "testprog", "ThreadExhaustion")
want := "runtime: program exceeds 10-thread limit\nfatal error: thread exhaustion"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecursivePanic(t *testing.T) {
output := runTestProg(t, "testprog", "RecursivePanic")
want := `wrap: bad
panic: again
`
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecursivePanic2(t *testing.T) {
output := runTestProg(t, "testprog", "RecursivePanic2")
want := `first panic
second panic
panic: third panic
`
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecursivePanic3(t *testing.T) {
output := runTestProg(t, "testprog", "RecursivePanic3")
want := `panic: first panic
`
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecursivePanic4(t *testing.T) {
output := runTestProg(t, "testprog", "RecursivePanic4")
want := `panic: first panic [recovered]
panic: second panic
`
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecursivePanic5(t *testing.T) {
output := runTestProg(t, "testprog", "RecursivePanic5")
want := `first panic
second panic
panic: third panic
`
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestGoexitCrash(t *testing.T) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
output := runTestProg(t, "testprog", "GoexitExit")
want := "no goroutines (main called runtime.Goexit) - deadlock!"
if !strings.Contains(output, want) {
t.Fatalf("output:\n%s\n\nwant output containing: %s", output, want)
}
}
func TestGoexitDefer(t *testing.T) {
c := make(chan struct{})
go func() {
defer func() {
r := recover()
if r != nil {
t.Errorf("non-nil recover during Goexit")
}
c <- struct{}{}
}()
runtime.Goexit()
}()
// Note: if the defer fails to run, we will get a deadlock here
<-c
}
func TestGoNil(t *testing.T) {
output := runTestProg(t, "testprog", "GoNil")
want := "go of nil func value"
if !strings.Contains(output, want) {
t.Fatalf("output:\n%s\n\nwant output containing: %s", output, want)
}
}
func TestMainGoroutineID(t *testing.T) {
output := runTestProg(t, "testprog", "MainGoroutineID")
want := "panic: test\n\ngoroutine 1 [running]:\n"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestNoHelperGoroutines(t *testing.T) {
output := runTestProg(t, "testprog", "NoHelperGoroutines")
matches := regexp.MustCompile(`goroutine [0-9]+ \[`).FindAllStringSubmatch(output, -1)
if len(matches) != 1 || matches[0][0] != "goroutine 1 [" {
t.Fatalf("want to see only goroutine 1, see:\n%s", output)
}
}
func TestBreakpoint(t *testing.T) {
output := runTestProg(t, "testprog", "Breakpoint")
// If runtime.Breakpoint() is inlined, then the stack trace prints
// "runtime.Breakpoint(...)" instead of "runtime.Breakpoint()".
// For gccgo, no parens.
want := "runtime.Breakpoint"
if !strings.Contains(output, want) {
t.Fatalf("output:\n%s\n\nwant output containing: %s", output, want)
}
}
func TestGoexitInPanic(t *testing.T) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
// see issue 8774: this code used to trigger an infinite recursion
output := runTestProg(t, "testprog", "GoexitInPanic")
want := "fatal error: no goroutines (main called runtime.Goexit) - deadlock!"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
// Issue 14965: Runtime panics should be of type runtime.Error
func TestRuntimePanicWithRuntimeError(t *testing.T) {
testCases := [...]func(){
0: func() {
var m map[uint64]bool
m[1234] = true
},
1: func() {
ch := make(chan struct{})
close(ch)
close(ch)
},
2: func() {
var ch = make(chan struct{})
close(ch)
ch <- struct{}{}
},
3: func() {
var s = make([]int, 2)
_ = s[2]
},
4: func() {
n := -1
_ = make(chan bool, n)
},
5: func() {
close((chan bool)(nil))
},
}
for i, fn := range testCases {
got := panicValue(fn)
if _, ok := got.(runtime.Error); !ok {
t.Errorf("test #%d: recovered value %v(type %T) does not implement runtime.Error", i, got, got)
}
}
}
func panicValue(fn func()) (recovered any) {
defer func() {
recovered = recover()
}()
fn()
return
}
func TestPanicAfterGoexit(t *testing.T) {
// an uncaught panic should still work after goexit
output := runTestProg(t, "testprog", "PanicAfterGoexit")
want := "panic: hello"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecoveredPanicAfterGoexit(t *testing.T) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
output := runTestProg(t, "testprog", "RecoveredPanicAfterGoexit")
want := "fatal error: no goroutines (main called runtime.Goexit) - deadlock!"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecoverBeforePanicAfterGoexit(t *testing.T) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
t.Parallel()
output := runTestProg(t, "testprog", "RecoverBeforePanicAfterGoexit")
want := "fatal error: no goroutines (main called runtime.Goexit) - deadlock!"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestRecoverBeforePanicAfterGoexit2(t *testing.T) {
// External linking brings in cgo, causing deadlock detection not working.
testenv.MustInternalLink(t)
t.Parallel()
output := runTestProg(t, "testprog", "RecoverBeforePanicAfterGoexit2")
want := "fatal error: no goroutines (main called runtime.Goexit) - deadlock!"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestNetpollDeadlock(t *testing.T) {
t.Parallel()
output := runTestProg(t, "testprognet", "NetpollDeadlock")
want := "done\n"
if !strings.HasSuffix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestPanicTraceback(t *testing.T) {
t.Parallel()
output := runTestProg(t, "testprog", "PanicTraceback")
want := "panic: hello\n\tpanic: panic pt2\n\tpanic: panic pt1\n"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
// Check functions in the traceback.
fns := []string{"main.pt1.func1", "panic", "main.pt2.func1", "panic", "main.pt2", "main.pt1"}
if runtime.Compiler == "gccgo" {
fns = []string{"main.pt1..func1", "panic", "main.pt2..func1", "panic", "main.pt2", "main.pt1"}
}
for _, fn := range fns {
var re *regexp.Regexp
if runtime.Compiler != "gccgo" {
re = regexp.MustCompile(`(?m)^` + regexp.QuoteMeta(fn) + `\(.*\n`)
} else {
re = regexp.MustCompile(`(?m)^` + regexp.QuoteMeta(fn) + `.*\n`)
}
idx := re.FindStringIndex(output)
if idx == nil {
t.Fatalf("expected %q function in traceback:\n%s", fn, output)
}
output = output[idx[1]:]
}
}
func testPanicDeadlock(t *testing.T, name string, want string) {
// test issue 14432
output := runTestProg(t, "testprog", name)
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestPanicDeadlockGosched(t *testing.T) {
testPanicDeadlock(t, "GoschedInPanic", "panic: errorThatGosched\n\n")
}
func TestPanicDeadlockSyscall(t *testing.T) {
testPanicDeadlock(t, "SyscallInPanic", "1\n2\npanic: 3\n\n")
}
func TestPanicLoop(t *testing.T) {
output := runTestProg(t, "testprog", "PanicLoop")
if want := "panic while printing panic value"; !strings.Contains(output, want) {
t.Errorf("output does not contain %q:\n%s", want, output)
}
}
func TestMemPprof(t *testing.T) {
testenv.MustHaveGoRun(t)
if runtime.Compiler == "gccgo" {
t.Skip("gccgo may not have the pprof tool")
}
exe, err := buildTestProg(t, "testprog")
if err != nil {
t.Fatal(err)
}
got, err := testenv.CleanCmdEnv(exec.Command(exe, "MemProf")).CombinedOutput()
if err != nil {
t.Fatal(err)
}
fn := strings.TrimSpace(string(got))
defer os.Remove(fn)
for try := 0; try < 2; try++ {
cmd := testenv.CleanCmdEnv(exec.Command(testenv.GoToolPath(t), "tool", "pprof", "-alloc_space", "-top"))
// Check that pprof works both with and without explicit executable on command line.
if try == 0 {
cmd.Args = append(cmd.Args, exe, fn)
} else {
cmd.Args = append(cmd.Args, fn)
}
found := false
for i, e := range cmd.Env {
if strings.HasPrefix(e, "PPROF_TMPDIR=") {
cmd.Env[i] = "PPROF_TMPDIR=" + os.TempDir()
found = true
break
}
}
if !found {
cmd.Env = append(cmd.Env, "PPROF_TMPDIR="+os.TempDir())
}
top, err := cmd.CombinedOutput()
t.Logf("%s:\n%s", cmd.Args, top)
if err != nil {
t.Error(err)
} else if !bytes.Contains(top, []byte("MemProf")) {
t.Error("missing MemProf in pprof output")
}
}
}
var concurrentMapTest = flag.Bool("run_concurrent_map_tests", false, "also run flaky concurrent map tests")
func TestConcurrentMapWrites(t *testing.T) {
if !*concurrentMapTest {
t.Skip("skipping without -run_concurrent_map_tests")
}
testenv.MustHaveGoRun(t)
output := runTestProg(t, "testprog", "concurrentMapWrites")
want := "fatal error: concurrent map writes"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestConcurrentMapReadWrite(t *testing.T) {
if !*concurrentMapTest {
t.Skip("skipping without -run_concurrent_map_tests")
}
testenv.MustHaveGoRun(t)
output := runTestProg(t, "testprog", "concurrentMapReadWrite")
want := "fatal error: concurrent map read and map write"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
func TestConcurrentMapIterateWrite(t *testing.T) {
if !*concurrentMapTest {
t.Skip("skipping without -run_concurrent_map_tests")
}
testenv.MustHaveGoRun(t)
output := runTestProg(t, "testprog", "concurrentMapIterateWrite")
want := "fatal error: concurrent map iteration and map write"
if !strings.HasPrefix(output, want) {
t.Fatalf("output does not start with %q:\n%s", want, output)
}
}
type point struct {
x, y *int
}
func (p *point) negate() {
*p.x = *p.x * -1
*p.y = *p.y * -1
}
// Test for issue #10152.
func TestPanicInlined(t *testing.T) {
defer func() {
r := recover()
if r == nil {
t.Fatalf("recover failed")
}
buf := make([]byte, 2048)
n := runtime.Stack(buf, false)
buf = buf[:n]
want := []byte("(*point).negate(")
if runtime.Compiler == "gccgo" {
want = []byte("point.negate")
}
if !bytes.Contains(buf, want) {
t.Logf("%s", buf)
t.Fatalf("expecting stack trace to contain call to %s", want)
}
}()
pt := new(point)
pt.negate()
}
// Test for issues #3934 and #20018.
// We want to delay exiting until a panic print is complete.
func TestPanicRace(t *testing.T) {
testenv.MustHaveGoRun(t)
exe, err := buildTestProg(t, "testprog")
if err != nil {
t.Fatal(err)
}
// The test is intentionally racy, and in my testing does not
// produce the expected output about 0.05% of the time.
// So run the program in a loop and only fail the test if we
// get the wrong output ten times in a row.
const tries = 10
retry:
for i := 0; i < tries; i++ {
got, err := testenv.CleanCmdEnv(exec.Command(exe, "PanicRace")).CombinedOutput()
if err == nil {
t.Logf("try %d: program exited successfully, should have failed", i+1)
continue
}
if i > 0 {
t.Logf("try %d:\n", i+1)
}
t.Logf("%s\n", got)
wants := []string{
"panic: crash",
"PanicRace",
"created by ",
}
if runtime.Compiler == "gccgo" {
// gccgo will dump a function name like main.$nested30.
// Match on the file name instead.
wants[1] = "panicrace"
}
for _, want := range wants {
if !bytes.Contains(got, []byte(want)) {
t.Logf("did not find expected string %q", want)
continue retry
}
}
// Test generated expected output.
return
}
t.Errorf("test ran %d times without producing expected output", tries)
}
func TestBadTraceback(t *testing.T) {
if runtime.Compiler == "gccgo" {
t.Skip("gccgo does not do a hex dump")
}
output := runTestProg(t, "testprog", "BadTraceback")
for _, want := range []string{
"runtime: unexpected return pc",
"called from 0xbad",
"00000bad", // Smashed LR in hex dump
"<main.badLR", // Symbolization in hex dump (badLR1 or badLR2)
} {
if !strings.Contains(output, want) {
t.Errorf("output does not contain %q:\n%s", want, output)
}
}
}
func TestTimePprof(t *testing.T) {
if runtime.Compiler == "gccgo" {
t.Skip("gccgo may not have the pprof tool")
}
// This test is unreliable on any system in which nanotime
// calls into libc.
switch runtime.GOOS {
case "aix", "darwin", "illumos", "openbsd", "solaris":
t.Skipf("skipping on %s because nanotime calls libc", runtime.GOOS)
}
// Pass GOTRACEBACK for issue #41120 to try to get more
// information on timeout.
fn := runTestProg(t, "testprog", "TimeProf", "GOTRACEBACK=crash")
fn = strings.TrimSpace(fn)
defer os.Remove(fn)
cmd := testenv.CleanCmdEnv(exec.Command(testenv.GoToolPath(t), "tool", "pprof", "-top", "-nodecount=1", fn))
cmd.Env = append(cmd.Env, "PPROF_TMPDIR="+os.TempDir())
top, err := cmd.CombinedOutput()
t.Logf("%s", top)
if err != nil {
t.Error(err)
} else if bytes.Contains(top, []byte("ExternalCode")) {
t.Error("profiler refers to ExternalCode")
}
}
// Test that runtime.abort does so.
func TestAbort(t *testing.T) {
if runtime.Compiler == "gccgo" && runtime.GOOS == "solaris" {
t.Skip("not supported by gofrontend on Solaris")
}
// Pass GOTRACEBACK to ensure we get runtime frames.
output := runTestProg(t, "testprog", "Abort", "GOTRACEBACK=system")
if want := "runtime.abort"; !strings.Contains(output, want) {
t.Errorf("output does not contain %q:\n%s", want, output)
}
if strings.Contains(output, "BAD") {
t.Errorf("output contains BAD:\n%s", output)
}
// Check that it's a signal traceback.
want := "PC="
// For systems that use a breakpoint, check specifically for that.
if runtime.Compiler == "gc" {
switch runtime.GOARCH {
case "386", "amd64":
switch runtime.GOOS {
case "plan9":
want = "sys: breakpoint"
case "windows":
want = "Exception 0x80000003"
default:
want = "SIGTRAP"
}
}
}
if !strings.Contains(output, want) {
t.Errorf("output does not contain %q:\n%s", want, output)
}
}
// For TestRuntimePanic: test a panic in the runtime package without
// involving the testing harness.
func init() {
if os.Getenv("GO_TEST_RUNTIME_PANIC") == "1" {
defer func() {
if r := recover(); r != nil {
// We expect to crash, so exit 0
// to indicate failure.
os.Exit(0)
}
}()
runtime.PanicForTesting(nil, 1)
// We expect to crash, so exit 0 to indicate failure.
os.Exit(0)
}
}
func TestRuntimePanic(t *testing.T) {
testenv.MustHaveExec(t)
cmd := testenv.CleanCmdEnv(exec.Command(os.Args[0], "-test.run=TestRuntimePanic"))
cmd.Env = append(cmd.Env, "GO_TEST_RUNTIME_PANIC=1")
out, err := cmd.CombinedOutput()
t.Logf("%s", out)
if err == nil {
t.Error("child process did not fail")
} else if want := "runtime.unexportedPanicForTesting"; !bytes.Contains(out, []byte(want)) {
t.Errorf("output did not contain expected string %q", want)
}
}
// Test that g0 stack overflows are handled gracefully.
func TestG0StackOverflow(t *testing.T) {
if runtime.Compiler == "gccgo" {
t.Skip("g0 stack overflow not supported by gofrontend")
}
testenv.MustHaveExec(t)
switch runtime.GOOS {
case "darwin", "dragonfly", "freebsd", "linux", "netbsd", "openbsd", "android":
t.Skipf("g0 stack is wrong on pthread platforms (see golang.org/issue/26061)")
}
if os.Getenv("TEST_G0_STACK_OVERFLOW") != "1" {
cmd := testenv.CleanCmdEnv(exec.Command(os.Args[0], "-test.run=TestG0StackOverflow", "-test.v"))
cmd.Env = append(cmd.Env, "TEST_G0_STACK_OVERFLOW=1")
out, err := cmd.CombinedOutput()
// Don't check err since it's expected to crash.
if n := strings.Count(string(out), "morestack on g0\n"); n != 1 {
t.Fatalf("%s\n(exit status %v)", out, err)
}
// Check that it's a signal-style traceback.
if runtime.GOOS != "windows" {
if want := "PC="; !strings.Contains(string(out), want) {
t.Errorf("output does not contain %q:\n%s", want, out)
}
}
return
}
runtime.G0StackOverflow()
}
// Test that panic message is not clobbered.
// See issue 30150.
func TestDoublePanic(t *testing.T) {
output := runTestProg(t, "testprog", "DoublePanic", "GODEBUG=clobberfree=1")
wants := []string{"panic: XXX", "panic: YYY"}
for _, want := range wants {
if !strings.Contains(output, want) {
t.Errorf("output:\n%s\n\nwant output containing: %s", output, want)
}
}
}