// Copyright 2009 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 testing provides support for automated testing of Go packages.
// It is intended to be used in concert with the ``go test'' command, which automates
// execution of any function of the form
// func TestXxx(*testing.T)
// where Xxx can be any alphanumeric string (but the first letter must not be in
// [a-z]) and serves to identify the test routine.
//
// Within these functions, use the Error, Fail or related methods to signal failure.
//
// To write a new test suite, create a file whose name ends _test.go that
// contains the TestXxx functions as described here. Put the file in the same
// package as the one being tested. The file will be excluded from regular
// package builds but will be included when the ``go test'' command is run.
// For more detail, run ``go help test'' and ``go help testflag''.
//
// Tests and benchmarks may be skipped if not applicable with a call to
// the Skip method of *T and *B:
// func TestTimeConsuming(t *testing.T) {
// if testing.Short() {
// t.Skip("skipping test in short mode.")
// }
// ...
// }
//
// Benchmarks
//
// Functions of the form
// func BenchmarkXxx(*testing.B)
// are considered benchmarks, and are executed by the "go test" command when
// its -bench flag is provided. Benchmarks are run sequentially.
//
// For a description of the testing flags, see
// https://golang.org/cmd/go/#hdr-Description_of_testing_flags.
//
// A sample benchmark function looks like this:
// func BenchmarkHello(b *testing.B) {
// for i := 0; i < b.N; i++ {
// fmt.Sprintf("hello")
// }
// }
//
// The benchmark function must run the target code b.N times.
// During benchmark execution, b.N is adjusted until the benchmark function lasts
// long enough to be timed reliably. The output
// BenchmarkHello 10000000 282 ns/op
// means that the loop ran 10000000 times at a speed of 282 ns per loop.
//
// If a benchmark needs some expensive setup before running, the timer
// may be reset:
//
// func BenchmarkBigLen(b *testing.B) {
// big := NewBig()
// b.ResetTimer()
// for i := 0; i < b.N; i++ {
// big.Len()
// }
// }
//
// If a benchmark needs to test performance in a parallel setting, it may use
// the RunParallel helper function; such benchmarks are intended to be used with
// the go test -cpu flag:
//
// func BenchmarkTemplateParallel(b *testing.B) {
// templ := template.Must(template.New("test").Parse("Hello, {{.}}!"))
// b.RunParallel(func(pb *testing.PB) {
// var buf bytes.Buffer
// for pb.Next() {
// buf.Reset()
// templ.Execute(&buf, "World")
// }
// })
// }
//
// Examples
//
// The package also runs and verifies example code. Example functions may
// include a concluding line comment that begins with "Output:" and is compared with
// the standard output of the function when the tests are run. (The comparison
// ignores leading and trailing space.) These are examples of an example:
//
// func ExampleHello() {
// fmt.Println("hello")
// // Output: hello
// }
//
// func ExampleSalutations() {
// fmt.Println("hello, and")
// fmt.Println("goodbye")
// // Output:
// // hello, and
// // goodbye
// }
//
// Example functions without output comments are compiled but not executed.
//
// The naming convention to declare examples for the package, a function F, a type T and
// method M on type T are:
//
// func Example() { ... }
// func ExampleF() { ... }
// func ExampleT() { ... }
// func ExampleT_M() { ... }
//
// Multiple example functions for a package/type/function/method may be provided by
// appending a distinct suffix to the name. The suffix must start with a
// lower-case letter.
//
// func Example_suffix() { ... }
// func ExampleF_suffix() { ... }
// func ExampleT_suffix() { ... }
// func ExampleT_M_suffix() { ... }
//
// The entire test file is presented as the example when it contains a single
// example function, at least one other function, type, variable, or constant
// declaration, and no test or benchmark functions.
//
// Main
//
// It is sometimes necessary for a test program to do extra setup or teardown
// before or after testing. It is also sometimes necessary for a test to control
// which code runs on the main thread. To support these and other cases,
// if a test file contains a function:
//
// func TestMain(m *testing.M)
//
// then the generated test will call TestMain(m) instead of running the tests
// directly. TestMain runs in the main goroutine and can do whatever setup
// and teardown is necessary around a call to m.Run. It should then call
// os.Exit with the result of m.Run. When TestMain is called, flag.Parse has
// not been run. If TestMain depends on command-line flags, including those
// of the testing package, it should call flag.Parse explicitly.
//
// A simple implementation of TestMain is:
//
// func TestMain(m *testing.M) {
// flag.Parse()
// os.Exit(m.Run())
// }
//
package testing
import (
"bytes"
"flag"
"fmt"
"os"
"runtime"
"runtime/pprof"
"runtime/trace"
"strconv"
"strings"
"sync"
"time"
)
var (
// The short flag requests that tests run more quickly, but its functionality
// is provided by test writers themselves. The testing package is just its
// home. The all.bash installation script sets it to make installation more
// efficient, but by default the flag is off so a plain "go test" will do a
// full test of the package.
short = flag.Bool("test.short", false, "run smaller test suite to save time")
// The directory in which to create profile files and the like. When run from
// "go test", the binary always runs in the source directory for the package;
// this flag lets "go test" tell the binary to write the files in the directory where
// the "go test" command is run.
outputDir = flag.String("test.outputdir", "", "directory in which to write profiles")
// Report as tests are run; default is silent for success.
chatty = flag.Bool("test.v", false, "verbose: print additional output")
count = flag.Uint("test.count", 1, "run tests and benchmarks `n` times")
coverProfile = flag.String("test.coverprofile", "", "write a coverage profile to the named file after execution")
match = flag.String("test.run", "", "regular expression to select tests and examples to run")
memProfile = flag.String("test.memprofile", "", "write a memory profile to the named file after execution")
memProfileRate = flag.Int("test.memprofilerate", 0, "if >=0, sets runtime.MemProfileRate")
cpuProfile = flag.String("test.cpuprofile", "", "write a cpu profile to the named file during execution")
blockProfile = flag.String("test.blockprofile", "", "write a goroutine blocking profile to the named file after execution")
blockProfileRate = flag.Int("test.blockprofilerate", 1, "if >= 0, calls runtime.SetBlockProfileRate()")
traceFile = flag.String("test.trace", "", "write an execution trace to the named file after execution")
timeout = flag.Duration("test.timeout", 0, "if positive, sets an aggregate time limit for all tests")
cpuListStr = flag.String("test.cpu", "", "comma-separated list of number of CPUs to use for each test")
parallel = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "maximum test parallelism")
haveExamples bool // are there examples?
cpuList []int
)
// common holds the elements common between T and B and
// captures common methods such as Errorf.
type common struct {
mu sync.RWMutex // guards output and failed
output []byte // Output generated by test or benchmark.
failed bool // Test or benchmark has failed.
skipped bool // Test of benchmark has been skipped.
finished bool
start time.Time // Time test or benchmark started
duration time.Duration
self interface{} // To be sent on signal channel when done.
signal chan interface{} // Output for serial tests.
}
// Short reports whether the -test.short flag is set.
func Short() bool {
return *short
}
// Verbose reports whether the -test.v flag is set.
func Verbose() bool {
return *chatty
}
// decorate prefixes the string with the file and line of the call site
// and inserts the final newline if needed and indentation tabs for formatting.
func decorate(s string) string {
_, file, line, ok := runtime.Caller(3) // decorate + log + public function.
if ok {
// Truncate file name at last file name separator.
if index := strings.LastIndex(file, "/"); index >= 0 {
file = file[index+1:]
} else if index = strings.LastIndex(file, "\\"); index >= 0 {
file = file[index+1:]
}
} else {
file = "???"
line = 1
}
buf := new(bytes.Buffer)
// Every line is indented at least one tab.
buf.WriteByte('\t')
fmt.Fprintf(buf, "%s:%d: ", file, line)
lines := strings.Split(s, "\n")
if l := len(lines); l > 1 && lines[l-1] == "" {
lines = lines[:l-1]
}
for i, line := range lines {
if i > 0 {
// Second and subsequent lines are indented an extra tab.
buf.WriteString("\n\t\t")
}
buf.WriteString(line)
}
buf.WriteByte('\n')
return buf.String()
}
// fmtDuration returns a string representing d in the form "87.00s".
func fmtDuration(d time.Duration) string {
return fmt.Sprintf("%.2fs", d.Seconds())
}
// TB is the interface common to T and B.
type TB interface {
Error(args ...interface{})
Errorf(format string, args ...interface{})
Fail()
FailNow()
Failed() bool
Fatal(args ...interface{})
Fatalf(format string, args ...interface{})
Log(args ...interface{})
Logf(format string, args ...interface{})
Skip(args ...interface{})
SkipNow()
Skipf(format string, args ...interface{})
Skipped() bool
// A private method to prevent users implementing the
// interface and so future additions to it will not
// violate Go 1 compatibility.
private()
}
var _ TB = (*T)(nil)
var _ TB = (*B)(nil)
// T is a type passed to Test functions to manage test state and support formatted test logs.
// Logs are accumulated during execution and dumped to standard error when done.
type T struct {
common
name string // Name of test.
startParallel chan bool // Parallel tests will wait on this.
}
func (c *common) private() {}
// Fail marks the function as having failed but continues execution.
func (c *common) Fail() {
c.mu.Lock()
defer c.mu.Unlock()
c.failed = true
}
// Failed reports whether the function has failed.
func (c *common) Failed() bool {
c.mu.RLock()
defer c.mu.RUnlock()
return c.failed
}
// FailNow marks the function as having failed and stops its execution.
// Execution will continue at the next test or benchmark.
// FailNow must be called from the goroutine running the
// test or benchmark function, not from other goroutines
// created during the test. Calling FailNow does not stop
// those other goroutines.
func (c *common) FailNow() {
c.Fail()
// Calling runtime.Goexit will exit the goroutine, which
// will run the deferred functions in this goroutine,
// which will eventually run the deferred lines in tRunner,
// which will signal to the test loop that this test is done.
//
// A previous version of this code said:
//
// c.duration = ...
// c.signal <- c.self
// runtime.Goexit()
//
// This previous version duplicated code (those lines are in
// tRunner no matter what), but worse the goroutine teardown
// implicit in runtime.Goexit was not guaranteed to complete
// before the test exited. If a test deferred an important cleanup
// function (like removing temporary files), there was no guarantee
// it would run on a test failure. Because we send on c.signal during
// a top-of-stack deferred function now, we know that the send
// only happens after any other stacked defers have completed.
c.finished = true
runtime.Goexit()
}
// log generates the output. It's always at the same stack depth.
func (c *common) log(s string) {
c.mu.Lock()
defer c.mu.Unlock()
c.output = append(c.output, decorate(s)...)
}
// Log formats its arguments using default formatting, analogous to Println,
// and records the text in the error log. For tests, the text will be printed only if
// the test fails or the -test.v flag is set. For benchmarks, the text is always
// printed to avoid having performance depend on the value of the -test.v flag.
func (c *common) Log(args ...interface{}) { c.log(fmt.Sprintln(args...)) }
// Logf formats its arguments according to the format, analogous to Printf,
// and records the text in the error log. For tests, the text will be printed only if
// the test fails or the -test.v flag is set. For benchmarks, the text is always
// printed to avoid having performance depend on the value of the -test.v flag.
func (c *common) Logf(format string, args ...interface{}) { c.log(fmt.Sprintf(format, args...)) }
// Error is equivalent to Log followed by Fail.
func (c *common) Error(args ...interface{}) {
c.log(fmt.Sprintln(args...))
c.Fail()
}
// Errorf is equivalent to Logf followed by Fail.
func (c *common) Errorf(format string, args ...interface{}) {
c.log(fmt.Sprintf(format, args...))
c.Fail()
}
// Fatal is equivalent to Log followed by FailNow.
func (c *common) Fatal(args ...interface{}) {
c.log(fmt.Sprintln(args...))
c.FailNow()
}
// Fatalf is equivalent to Logf followed by FailNow.
func (c *common) Fatalf(format string, args ...interface{}) {
c.log(fmt.Sprintf(format, args...))
c.FailNow()
}
// Skip is equivalent to Log followed by SkipNow.
func (c *common) Skip(args ...interface{}) {
c.log(fmt.Sprintln(args...))
c.SkipNow()
}
// Skipf is equivalent to Logf followed by SkipNow.
func (c *common) Skipf(format string, args ...interface{}) {
c.log(fmt.Sprintf(format, args...))
c.SkipNow()
}
// SkipNow marks the test as having been skipped and stops its execution.
// Execution will continue at the next test or benchmark. See also FailNow.
// SkipNow must be called from the goroutine running the test, not from
// other goroutines created during the test. Calling SkipNow does not stop
// those other goroutines.
func (c *common) SkipNow() {
c.skip()
c.finished = true
runtime.Goexit()
}
func (c *common) skip() {
c.mu.Lock()
defer c.mu.Unlock()
c.skipped = true
}
// Skipped reports whether the test was skipped.
func (c *common) Skipped() bool {
c.mu.RLock()
defer c.mu.RUnlock()
return c.skipped
}
// Parallel signals that this test is to be run in parallel with (and only with)
// other parallel tests.
func (t *T) Parallel() {
t.signal <- (*T)(nil) // Release main testing loop
<-t.startParallel // Wait for serial tests to finish
// Assuming Parallel is the first thing a test does, which is reasonable,
// reinitialize the test's start time because it's actually starting now.
t.start = time.Now()
}
// An internal type but exported because it is cross-package; part of the implementation
// of the "go test" command.
type InternalTest struct {
Name string
F func(*T)
}
func tRunner(t *T, test *InternalTest) {
// When this goroutine is done, either because test.F(t)
// returned normally or because a test failure triggered
// a call to runtime.Goexit, record the duration and send
// a signal saying that the test is done.
defer func() {
t.duration = time.Now().Sub(t.start)
// If the test panicked, print any test output before dying.
err := recover()
if !t.finished && err == nil {
err = fmt.Errorf("test executed panic(nil) or runtime.Goexit")
}
if err != nil {
t.Fail()
t.report()
panic(err)
}
t.signal <- t
}()
t.start = time.Now()
test.F(t)
t.finished = true
}
// An internal function but exported because it is cross-package; part of the implementation
// of the "go test" command.
func Main(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
os.Exit(MainStart(matchString, tests, benchmarks, examples).Run())
}
// M is a type passed to a TestMain function to run the actual tests.
type M struct {
matchString func(pat, str string) (bool, error)
tests []InternalTest
benchmarks []InternalBenchmark
examples []InternalExample
}
// MainStart is meant for use by tests generated by 'go test'.
// It is not meant to be called directly and is not subject to the Go 1 compatibility document.
// It may change signature from release to release.
func MainStart(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) *M {
return &M{
matchString: matchString,
tests: tests,
benchmarks: benchmarks,
examples: examples,
}
}
// Run runs the tests. It returns an exit code to pass to os.Exit.
func (m *M) Run() int {
flag.Parse()
parseCpuList()
before()
startAlarm()
haveExamples = len(m.examples) > 0
testOk := RunTests(m.matchString, m.tests)
exampleOk := RunExamples(m.matchString, m.examples)
stopAlarm()
if !testOk || !exampleOk {
fmt.Println("FAIL")
after()
return 1
}
fmt.Println("PASS")
RunBenchmarks(m.matchString, m.benchmarks)
after()
return 0
}
func (t *T) report() {
dstr := fmtDuration(t.duration)
format := "--- %s: %s (%s)\n%s"
if t.Failed() {
fmt.Printf(format, "FAIL", t.name, dstr, t.output)
} else if *chatty {
if t.Skipped() {
fmt.Printf(format, "SKIP", t.name, dstr, t.output)
} else {
fmt.Printf(format, "PASS", t.name, dstr, t.output)
}
}
}
func RunTests(matchString func(pat, str string) (bool, error), tests []InternalTest) (ok bool) {
ok = true
if len(tests) == 0 && !haveExamples {
fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
return
}
for _, procs := range cpuList {
runtime.GOMAXPROCS(procs)
// We build a new channel tree for each run of the loop.
// collector merges in one channel all the upstream signals from parallel tests.
// If all tests pump to the same channel, a bug can occur where a test
// kicks off a goroutine that Fails, yet the test still delivers a completion signal,
// which skews the counting.
var collector = make(chan interface{})
numParallel := 0
startParallel := make(chan bool)
for i := 0; i < len(tests); i++ {
matched, err := matchString(*match, tests[i].Name)
if err != nil {
fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.run: %s\n", err)
os.Exit(1)
}
if !matched {
continue
}
testName := tests[i].Name
t := &T{
common: common{
signal: make(chan interface{}),
},
name: testName,
startParallel: startParallel,
}
t.self = t
if *chatty {
fmt.Printf("=== RUN %s\n", t.name)
}
go tRunner(t, &tests[i])
out := (<-t.signal).(*T)
if out == nil { // Parallel run.
go func() {
collector <- <-t.signal
}()
numParallel++
continue
}
t.report()
ok = ok && !out.Failed()
}
running := 0
for numParallel+running > 0 {
if running < *parallel && numParallel > 0 {
startParallel <- true
running++
numParallel--
continue
}
t := (<-collector).(*T)
t.report()
ok = ok && !t.Failed()
running--
}
}
return
}
// before runs before all testing.
func before() {
if *memProfileRate > 0 {
runtime.MemProfileRate = *memProfileRate
}
if *cpuProfile != "" {
f, err := os.Create(toOutputDir(*cpuProfile))
if err != nil {
fmt.Fprintf(os.Stderr, "testing: %s", err)
return
}
if err := pprof.StartCPUProfile(f); err != nil {
fmt.Fprintf(os.Stderr, "testing: can't start cpu profile: %s", err)
f.Close()
return
}
// Could save f so after can call f.Close; not worth the effort.
}
if *traceFile != "" {
f, err := os.Create(toOutputDir(*traceFile))
if err != nil {
fmt.Fprintf(os.Stderr, "testing: %s", err)
return
}
if err := trace.Start(f); err != nil {
fmt.Fprintf(os.Stderr, "testing: can't start tracing: %s", err)
f.Close()
return
}
// Could save f so after can call f.Close; not worth the effort.
}
if *blockProfile != "" && *blockProfileRate >= 0 {
runtime.SetBlockProfileRate(*blockProfileRate)
}
if *coverProfile != "" && cover.Mode == "" {
fmt.Fprintf(os.Stderr, "testing: cannot use -test.coverprofile because test binary was not built with coverage enabled\n")
os.Exit(2)
}
}
// after runs after all testing.
func after() {
if *cpuProfile != "" {
pprof.StopCPUProfile() // flushes profile to disk
}
if *traceFile != "" {
trace.Stop() // flushes trace to disk
}
if *memProfile != "" {
f, err := os.Create(toOutputDir(*memProfile))
if err != nil {
fmt.Fprintf(os.Stderr, "testing: %s\n", err)
os.Exit(2)
}
runtime.GC() // materialize all statistics
if err = pprof.WriteHeapProfile(f); err != nil {
fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *memProfile, err)
os.Exit(2)
}
f.Close()
}
if *blockProfile != "" && *blockProfileRate >= 0 {
f, err := os.Create(toOutputDir(*blockProfile))
if err != nil {
fmt.Fprintf(os.Stderr, "testing: %s\n", err)
os.Exit(2)
}
if err = pprof.Lookup("block").WriteTo(f, 0); err != nil {
fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *blockProfile, err)
os.Exit(2)
}
f.Close()
}
if cover.Mode != "" {
coverReport()
}
}
// toOutputDir returns the file name relocated, if required, to outputDir.
// Simple implementation to avoid pulling in path/filepath.
func toOutputDir(path string) string {
if *outputDir == "" || path == "" {
return path
}
if runtime.GOOS == "windows" {
// On Windows, it's clumsy, but we can be almost always correct
// by just looking for a drive letter and a colon.
// Absolute paths always have a drive letter (ignoring UNC).
// Problem: if path == "C:A" and outputdir == "C:\Go" it's unclear
// what to do, but even then path/filepath doesn't help.
// TODO: Worth doing better? Probably not, because we're here only
// under the management of go test.
if len(path) >= 2 {
letter, colon := path[0], path[1]
if ('a' <= letter && letter <= 'z' || 'A' <= letter && letter <= 'Z') && colon == ':' {
// If path starts with a drive letter we're stuck with it regardless.
return path
}
}
}
if os.IsPathSeparator(path[0]) {
return path
}
return fmt.Sprintf("%s%c%s", *outputDir, os.PathSeparator, path)
}
var timer *time.Timer
// startAlarm starts an alarm if requested.
func startAlarm() {
if *timeout > 0 {
timer = time.AfterFunc(*timeout, func() {
panic(fmt.Sprintf("test timed out after %v", *timeout))
})
}
}
// stopAlarm turns off the alarm.
func stopAlarm() {
if *timeout > 0 {
timer.Stop()
}
}
func parseCpuList() {
for _, val := range strings.Split(*cpuListStr, ",") {
val = strings.TrimSpace(val)
if val == "" {
continue
}
cpu, err := strconv.Atoi(val)
if err != nil || cpu <= 0 {
fmt.Fprintf(os.Stderr, "testing: invalid value %q for -test.cpu\n", val)
os.Exit(1)
}
for i := uint(0); i < *count; i++ {
cpuList = append(cpuList, cpu)
}
}
if cpuList == nil {
for i := uint(0); i < *count; i++ {
cpuList = append(cpuList, runtime.GOMAXPROCS(-1))
}
}
}