1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // Package testing provides support for automated testing of Go packages.
6 // It is intended to be used in concert with the "go test" command, which automates
7 // execution of any function of the form
8 // func TestXxx(*testing.T)
9 // where Xxx does not start with a lowercase letter. The function name
10 // serves to identify the test routine.
12 // Within these functions, use the Error, Fail or related methods to signal failure.
14 // To write a new test suite, create a file whose name ends _test.go that
15 // contains the TestXxx functions as described here. Put the file in the same
16 // package as the one being tested. The file will be excluded from regular
17 // package builds but will be included when the "go test" command is run.
18 // For more detail, run "go help test" and "go help testflag".
20 // A simple test function looks like this:
22 // func TestAbs(t *testing.T) {
25 // t.Errorf("Abs(-1) = %d; want 1", got)
31 // Functions of the form
32 // func BenchmarkXxx(*testing.B)
33 // are considered benchmarks, and are executed by the "go test" command when
34 // its -bench flag is provided. Benchmarks are run sequentially.
36 // For a description of the testing flags, see
37 // https://golang.org/cmd/go/#hdr-Testing_flags.
39 // A sample benchmark function looks like this:
40 // func BenchmarkRandInt(b *testing.B) {
41 // for i := 0; i < b.N; i++ {
46 // The benchmark function must run the target code b.N times.
47 // During benchmark execution, b.N is adjusted until the benchmark function lasts
48 // long enough to be timed reliably. The output
49 // BenchmarkRandInt-8 68453040 17.8 ns/op
50 // means that the loop ran 68453040 times at a speed of 17.8 ns per loop.
52 // If a benchmark needs some expensive setup before running, the timer
55 // func BenchmarkBigLen(b *testing.B) {
58 // for i := 0; i < b.N; i++ {
63 // If a benchmark needs to test performance in a parallel setting, it may use
64 // the RunParallel helper function; such benchmarks are intended to be used with
65 // the go test -cpu flag:
67 // func BenchmarkTemplateParallel(b *testing.B) {
68 // templ := template.Must(template.New("test").Parse("Hello, {{.}}!"))
69 // b.RunParallel(func(pb *testing.PB) {
70 // var buf bytes.Buffer
73 // templ.Execute(&buf, "World")
80 // The package also runs and verifies example code. Example functions may
81 // include a concluding line comment that begins with "Output:" and is compared with
82 // the standard output of the function when the tests are run. (The comparison
83 // ignores leading and trailing space.) These are examples of an example:
85 // func ExampleHello() {
86 // fmt.Println("hello")
90 // func ExampleSalutations() {
91 // fmt.Println("hello, and")
92 // fmt.Println("goodbye")
98 // The comment prefix "Unordered output:" is like "Output:", but matches any
101 // func ExamplePerm() {
102 // for _, value := range Perm(5) {
103 // fmt.Println(value)
105 // // Unordered output: 4
112 // Example functions without output comments are compiled but not executed.
114 // The naming convention to declare examples for the package, a function F, a type T and
115 // method M on type T are:
117 // func Example() { ... }
118 // func ExampleF() { ... }
119 // func ExampleT() { ... }
120 // func ExampleT_M() { ... }
122 // Multiple example functions for a package/type/function/method may be provided by
123 // appending a distinct suffix to the name. The suffix must start with a
124 // lower-case letter.
126 // func Example_suffix() { ... }
127 // func ExampleF_suffix() { ... }
128 // func ExampleT_suffix() { ... }
129 // func ExampleT_M_suffix() { ... }
131 // The entire test file is presented as the example when it contains a single
132 // example function, at least one other function, type, variable, or constant
133 // declaration, and no test or benchmark functions.
137 // Functions of the form
138 // func FuzzXxx(*testing.F)
139 // are considered fuzz targets, and are executed by the "go test" command. When
140 // the -fuzz flag is provided, the functions will be fuzzed.
142 // For a description of the testing flags, see
143 // https://golang.org/cmd/go/#hdr-Testing_flags.
145 // For a description of fuzzing, see golang.org/s/draft-fuzzing-design.
147 // A sample fuzz target looks like this:
148 // func FuzzBytesCmp(f *testing.F) {
149 // f.Fuzz(func(t *testing.T, a, b []byte) {
150 // if bytes.HasPrefix(a, b) && !bytes.Contains(a, b) {
151 // t.Error("HasPrefix is true, but Contains is false")
158 // Tests or benchmarks may be skipped at run time with a call to
159 // the Skip method of *T or *B:
161 // func TestTimeConsuming(t *testing.T) {
162 // if testing.Short() {
163 // t.Skip("skipping test in short mode.")
168 // The Skip method of *T can be used in a fuzz target if the input is invalid,
169 // but should not be considered a crash. For example:
171 // func FuzzJSONMarshalling(f *testing.F) {
172 // f.Fuzz(func(t *testing.T, b []byte) {
174 // if err := json.Unmarshal(b, &v); err != nil {
177 // if _, err := json.Marshal(v); err != nil {
178 // t.Error("Marshal: %v", err)
183 // Subtests and Sub-benchmarks
185 // The Run methods of T and B allow defining subtests and sub-benchmarks,
186 // without having to define separate functions for each. This enables uses
187 // like table-driven benchmarks and creating hierarchical tests.
188 // It also provides a way to share common setup and tear-down code:
190 // func TestFoo(t *testing.T) {
192 // t.Run("A=1", func(t *testing.T) { ... })
193 // t.Run("A=2", func(t *testing.T) { ... })
194 // t.Run("B=1", func(t *testing.T) { ... })
195 // // <tear-down code>
198 // Each subtest and sub-benchmark has a unique name: the combination of the name
199 // of the top-level test and the sequence of names passed to Run, separated by
200 // slashes, with an optional trailing sequence number for disambiguation.
202 // The argument to the -run, -bench, and -fuzz command-line flags is an unanchored regular
203 // expression that matches the test's name. For tests with multiple slash-separated
204 // elements, such as subtests, the argument is itself slash-separated, with
205 // expressions matching each name element in turn. Because it is unanchored, an
206 // empty expression matches any string.
207 // For example, using "matching" to mean "whose name contains":
209 // go test -run '' # Run all tests.
210 // go test -run Foo # Run top-level tests matching "Foo", such as "TestFooBar".
211 // go test -run Foo/A= # For top-level tests matching "Foo", run subtests matching "A=".
212 // go test -run /A=1 # For all top-level tests, run subtests matching "A=1".
213 // go test -fuzz FuzzFoo # Fuzz the target matching "FuzzFoo"
215 // The -run argument can also be used to run a specific value in the seed
216 // corpus, for debugging. For example:
217 // go test -run=FuzzFoo/9ddb952d9814
219 // The -fuzz and -run flags can both be set, in order to fuzz a target but
220 // skip the execution of all other tests.
222 // Subtests can also be used to control parallelism. A parent test will only
223 // complete once all of its subtests complete. In this example, all tests are
224 // run in parallel with each other, and only with each other, regardless of
225 // other top-level tests that may be defined:
227 // func TestGroupedParallel(t *testing.T) {
228 // for _, tc := range tests {
229 // tc := tc // capture range variable
230 // t.Run(tc.Name, func(t *testing.T) {
237 // The race detector kills the program if it exceeds 8128 concurrent goroutines,
238 // so use care when running parallel tests with the -race flag set.
240 // Run does not return until parallel subtests have completed, providing a way
241 // to clean up after a group of parallel tests:
243 // func TestTeardownParallel(t *testing.T) {
244 // // This Run will not return until the parallel tests finish.
245 // t.Run("group", func(t *testing.T) {
246 // t.Run("Test1", parallelTest1)
247 // t.Run("Test2", parallelTest2)
248 // t.Run("Test3", parallelTest3)
250 // // <tear-down code>
255 // It is sometimes necessary for a test or benchmark program to do extra setup or teardown
256 // before or after it executes. It is also sometimes necessary to control
257 // which code runs on the main thread. To support these and other cases,
258 // if a test file contains a function:
260 // func TestMain(m *testing.M)
262 // then the generated test will call TestMain(m) instead of running the tests or benchmarks
263 // directly. TestMain runs in the main goroutine and can do whatever setup
264 // and teardown is necessary around a call to m.Run. m.Run will return an exit
265 // code that may be passed to os.Exit. If TestMain returns, the test wrapper
266 // will pass the result of m.Run to os.Exit itself.
268 // When TestMain is called, flag.Parse has not been run. If TestMain depends on
269 // command-line flags, including those of the testing package, it should call
270 // flag.Parse explicitly. Command line flags are always parsed by the time test
271 // or benchmark functions run.
273 // A simple implementation of TestMain is:
275 // func TestMain(m *testing.M) {
276 // // call flag.Parse() here if TestMain uses flags
306 // Init registers testing flags. These flags are automatically registered by
307 // the "go test" command before running test functions, so Init is only needed
308 // when calling functions such as Benchmark without using "go test".
310 // Init has no effect if it was already called.
316 // The short flag requests that tests run more quickly, but its functionality
317 // is provided by test writers themselves. The testing package is just its
318 // home. The all.bash installation script sets it to make installation more
319 // efficient, but by default the flag is off so a plain "go test" will do a
320 // full test of the package.
321 short = flag.Bool("test.short", false, "run smaller test suite to save time")
323 // The failfast flag requests that test execution stop after the first test failure.
324 failFast = flag.Bool("test.failfast", false, "do not start new tests after the first test failure")
326 // The directory in which to create profile files and the like. When run from
327 // "go test", the binary always runs in the source directory for the package;
328 // this flag lets "go test" tell the binary to write the files in the directory where
329 // the "go test" command is run.
330 outputDir = flag.String("test.outputdir", "", "write profiles to `dir`")
331 // Report as tests are run; default is silent for success.
332 chatty = flag.Bool("test.v", false, "verbose: print additional output")
333 count = flag.Uint("test.count", 1, "run tests and benchmarks `n` times")
334 coverProfile = flag.String("test.coverprofile", "", "write a coverage profile to `file`")
335 matchList = flag.String("test.list", "", "list tests, examples, and benchmarks matching `regexp` then exit")
336 match = flag.String("test.run", "", "run only tests and examples matching `regexp`")
337 memProfile = flag.String("test.memprofile", "", "write an allocation profile to `file`")
338 memProfileRate = flag.Int("test.memprofilerate", 0, "set memory allocation profiling `rate` (see runtime.MemProfileRate)")
339 cpuProfile = flag.String("test.cpuprofile", "", "write a cpu profile to `file`")
340 blockProfile = flag.String("test.blockprofile", "", "write a goroutine blocking profile to `file`")
341 blockProfileRate = flag.Int("test.blockprofilerate", 1, "set blocking profile `rate` (see runtime.SetBlockProfileRate)")
342 mutexProfile = flag.String("test.mutexprofile", "", "write a mutex contention profile to the named file after execution")
343 mutexProfileFraction = flag.Int("test.mutexprofilefraction", 1, "if >= 0, calls runtime.SetMutexProfileFraction()")
344 panicOnExit0 = flag.Bool("test.paniconexit0", false, "panic on call to os.Exit(0)")
345 traceFile = flag.String("test.trace", "", "write an execution trace to `file`")
346 timeout = flag.Duration("test.timeout", 0, "panic test binary after duration `d` (default 0, timeout disabled)")
347 cpuListStr = flag.String("test.cpu", "", "comma-separated `list` of cpu counts to run each test with")
348 parallel = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "run at most `n` tests in parallel")
349 testlog = flag.String("test.testlogfile", "", "write test action log to `file` (for use only by cmd/go)")
350 shuffle = flag.String("test.shuffle", "off", "randomize the execution order of tests and benchmarks")
357 // Flags, registered during Init.
370 blockProfileRate *int
372 mutexProfileFraction *int
375 timeout *time.Duration
381 haveExamples bool // are there examples?
386 numFailed uint32 // number of test failures
389 type chattyPrinter struct {
391 lastNameMu sync.Mutex // guards lastName
392 lastName string // last printed test name in chatty mode
395 func newChattyPrinter(w io.Writer) *chattyPrinter {
396 return &chattyPrinter{w: w}
399 // Updatef prints a message about the status of the named test to w.
401 // The formatted message must include the test name itself.
402 func (p *chattyPrinter) Updatef(testName, format string, args ...interface{}) {
404 defer p.lastNameMu.Unlock()
406 // Since the message already implies an association with a specific new test,
407 // we don't need to check what the old test name was or log an extra CONT line
408 // for it. (We're updating it anyway, and the current message already includes
410 p.lastName = testName
411 fmt.Fprintf(p.w, format, args...)
414 // Printf prints a message, generated by the named test, that does not
415 // necessarily mention that tests's name itself.
416 func (p *chattyPrinter) Printf(testName, format string, args ...interface{}) {
418 defer p.lastNameMu.Unlock()
420 if p.lastName == "" {
421 p.lastName = testName
422 } else if p.lastName != testName {
423 fmt.Fprintf(p.w, "=== CONT %s\n", testName)
424 p.lastName = testName
427 fmt.Fprintf(p.w, format, args...)
430 // The maximum number of stack frames to go through when skipping helper functions for
431 // the purpose of decorating log messages.
432 const maxStackLen = 50
434 // common holds the elements common between T and B and
435 // captures common methods such as Errorf.
437 mu sync.RWMutex // guards this group of fields
438 output []byte // Output generated by test or benchmark.
439 w io.Writer // For flushToParent.
440 ran bool // Test or benchmark (or one of its subtests) was executed.
441 failed bool // Test or benchmark has failed.
442 skipped bool // Test or benchmark has been skipped.
443 done bool // Test is finished and all subtests have completed.
444 helperPCs map[uintptr]struct{} // functions to be skipped when writing file/line info
445 helperNames map[string]struct{} // helperPCs converted to function names
446 cleanups []func() // optional functions to be called at the end of the test
447 cleanupName string // Name of the cleanup function.
448 cleanupPc []uintptr // The stack trace at the point where Cleanup was called.
449 finished bool // Test function has completed.
451 chatty *chattyPrinter // A copy of chattyPrinter, if the chatty flag is set.
452 bench bool // Whether the current test is a benchmark.
453 fuzzing bool // Whether the current test is a fuzzing target.
454 hasSub int32 // Written atomically.
455 raceErrors int // Number of races detected during test.
456 runner string // Function name of tRunner running the test.
459 level int // Nesting depth of test or benchmark.
460 creator []uintptr // If level > 0, the stack trace at the point where the parent called t.Run.
461 name string // Name of test or benchmark.
462 start time.Time // Time test or benchmark started
463 duration time.Duration
464 barrier chan bool // To signal parallel subtests they may start.
465 signal chan bool // To signal a test is done.
466 sub []*T // Queue of subtests to be run in parallel.
474 // Short reports whether the -test.short flag is set.
477 panic("testing: Short called before Init")
479 // Catch code that calls this from TestMain without first calling flag.Parse.
481 panic("testing: Short called before Parse")
487 // CoverMode reports what the test coverage mode is set to. The
488 // values are "set", "count", or "atomic". The return value will be
489 // empty if test coverage is not enabled.
490 func CoverMode() string {
494 // Verbose reports whether the -test.v flag is set.
495 func Verbose() bool {
498 panic("testing: Verbose called before Init")
501 panic("testing: Verbose called before Parse")
506 // frameSkip searches, starting after skip frames, for the first caller frame
507 // in a function not marked as a helper and returns that frame.
508 // The search stops if it finds a tRunner function that
509 // was the entry point into the test and the test is not a subtest.
510 // This function must be called with c.mu held.
511 func (c *common) frameSkip(skip int) runtime.Frame {
512 // If the search continues into the parent test, we'll have to hold
513 // its mu temporarily. If we then return, we need to unlock it.
514 shouldUnlock := false
520 var pc [maxStackLen]uintptr
521 // Skip two extra frames to account for this function
522 // and runtime.Callers itself.
523 n := runtime.Callers(skip+2, pc[:])
525 panic("testing: zero callers found")
527 frames := runtime.CallersFrames(pc[:n])
528 var firstFrame, prevFrame, frame runtime.Frame
529 for more := true; more; prevFrame = frame {
530 frame, more = frames.Next()
531 if frame.Function == c.cleanupName {
532 frames = runtime.CallersFrames(c.cleanupPc)
535 if firstFrame.PC == 0 {
538 if frame.Function == c.runner {
539 // We've gone up all the way to the tRunner calling
540 // the test function (so the user must have
541 // called tb.Helper from inside that test function).
542 // If this is a top-level test, only skip up to the test function itself.
543 // If we're in a subtest, continue searching in the parent test,
544 // starting from the point of the call to Run which created this subtest.
546 frames = runtime.CallersFrames(c.creator)
548 // We're no longer looking at the current c after this point,
549 // so we should unlock its mu, unless it's the original receiver,
550 // in which case our caller doesn't expect us to do that.
555 // Remember to unlock c.mu when we no longer need it, either
556 // because we went up another nesting level, or because we
564 // If more helper PCs have been added since we last did the conversion
565 if c.helperNames == nil {
566 c.helperNames = make(map[string]struct{})
567 for pc := range c.helperPCs {
568 c.helperNames[pcToName(pc)] = struct{}{}
571 if _, ok := c.helperNames[frame.Function]; !ok {
572 // Found a frame that wasn't inside a helper function.
579 // decorate prefixes the string with the file and line of the call site
580 // and inserts the final newline if needed and indentation spaces for formatting.
581 // This function must be called with c.mu held.
582 func (c *common) decorate(s string, skip int) string {
583 // TODO(jayconrod,katiehockman): Consider refactoring the logging logic.
584 // If more helper PCs have been added since we last did the conversion
585 if c.helperNames == nil {
586 c.helperNames = make(map[string]struct{})
587 for pc := range c.helperPCs {
588 c.helperNames[pcToName(pc)] = struct{}{}
592 frame := c.frameSkip(skip)
596 // Truncate file name at last file name separator.
597 if index := strings.LastIndex(file, "/"); index >= 0 {
598 file = file[index+1:]
599 } else if index = strings.LastIndex(file, "\\"); index >= 0 {
600 file = file[index+1:]
608 buf := new(strings.Builder)
609 // Every line is indented at least 4 spaces.
611 fmt.Fprintf(buf, "%s:%d: ", file, line)
612 lines := strings.Split(s, "\n")
613 if l := len(lines); l > 1 && lines[l-1] == "" {
616 for i, line := range lines {
618 // Second and subsequent lines are indented an additional 4 spaces.
619 buf.WriteString("\n ")
621 buf.WriteString(line)
627 // flushToParent writes c.output to the parent after first writing the header
628 // with the given format and arguments.
629 func (c *common) flushToParent(testName, format string, args ...interface{}) {
637 if len(c.output) > 0 {
639 args = append(args[:len(args):len(args)], c.output)
640 c.output = c.output[:0] // but why?
643 if c.chatty != nil && p.w == c.chatty.w {
644 // We're flushing to the actual output, so track that this output is
645 // associated with a specific test (and, specifically, that the next output
646 // is *not* associated with that test).
648 // Moreover, if c.output is non-empty it is important that this write be
649 // atomic with respect to the output of other tests, so that we don't end up
650 // with confusing '=== CONT' lines in the middle of our '--- PASS' block.
651 // Neither humans nor cmd/test2json can parse those easily.
652 // (See https://golang.org/issue/40771.)
653 c.chatty.Updatef(testName, format, args...)
655 // We're flushing to the output buffer of the parent test, which will
656 // itself follow a test-name header when it is finally flushed to stdout.
657 fmt.Fprintf(p.w, format, args...)
661 // isFuzzing returns whether the current context, or any of the parent contexts,
662 // are a fuzzing target
663 func (c *common) isFuzzing() bool {
667 for parent := c.parent; parent != nil; parent = parent.parent {
675 type indenter struct {
679 func (w indenter) Write(b []byte) (n int, err error) {
682 end := bytes.IndexByte(b, '\n')
688 // An indent of 4 spaces will neatly align the dashes with the status
689 // indicator of the parent.
691 w.c.output = append(w.c.output, indent...)
692 w.c.output = append(w.c.output, b[:end]...)
698 // fmtDuration returns a string representing d in the form "87.00s".
699 func fmtDuration(d time.Duration) string {
700 return fmt.Sprintf("%.2fs", d.Seconds())
703 // TB is the interface common to T and B.
706 Error(args ...interface{})
707 Errorf(format string, args ...interface{})
711 Fatal(args ...interface{})
712 Fatalf(format string, args ...interface{})
714 Log(args ...interface{})
715 Logf(format string, args ...interface{})
717 Skip(args ...interface{})
719 Skipf(format string, args ...interface{})
723 // A private method to prevent users implementing the
724 // interface and so future additions to it will not
725 // violate Go 1 compatibility.
732 // T is a type passed to Test functions to manage test state and support formatted test logs.
734 // A test ends when its Test function returns or calls any of the methods
735 // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods, as well as
736 // the Parallel method, must be called only from the goroutine running the
739 // The other reporting methods, such as the variations of Log and Error,
740 // may be called simultaneously from multiple goroutines.
745 context *testContext // For running tests and subtests.
748 func (c *common) private() {}
750 // Name returns the name of the running test or benchmark.
751 func (c *common) Name() string {
755 func (c *common) setRan() {
764 // Fail marks the function as having failed but continues execution.
765 func (c *common) Fail() {
771 // c.done needs to be locked to synchronize checks to c.done in parent tests.
773 panic("Fail in goroutine after " + c.name + " has completed")
778 // Failed reports whether the function has failed.
779 func (c *common) Failed() bool {
783 return failed || c.raceErrors+race.Errors() > 0
786 // FailNow marks the function as having failed and stops its execution
787 // by calling runtime.Goexit (which then runs all deferred calls in the
788 // current goroutine).
789 // Execution will continue at the next test or benchmark.
790 // FailNow must be called from the goroutine running the
791 // test or benchmark function, not from other goroutines
792 // created during the test. Calling FailNow does not stop
793 // those other goroutines.
794 func (c *common) FailNow() {
797 // Calling runtime.Goexit will exit the goroutine, which
798 // will run the deferred functions in this goroutine,
799 // which will eventually run the deferred lines in tRunner,
800 // which will signal to the test loop that this test is done.
802 // A previous version of this code said:
805 // c.signal <- c.self
808 // This previous version duplicated code (those lines are in
809 // tRunner no matter what), but worse the goroutine teardown
810 // implicit in runtime.Goexit was not guaranteed to complete
811 // before the test exited. If a test deferred an important cleanup
812 // function (like removing temporary files), there was no guarantee
813 // it would run on a test failure. Because we send on c.signal during
814 // a top-of-stack deferred function now, we know that the send
815 // only happens after any other stacked defers have completed.
822 // log generates the output. It's always at the same stack depth.
823 func (c *common) log(s string) {
824 c.logDepth(s, 3) // logDepth + log + public function
827 // logDepth generates the output at an arbitrary stack depth.
828 func (c *common) logDepth(s string, depth int) {
832 // This test has already finished. Try and log this message
833 // with our parent. If we don't have a parent, panic.
834 for parent := c.parent; parent != nil; parent = parent.parent {
836 defer parent.mu.Unlock()
838 parent.output = append(parent.output, parent.decorate(s, depth+1)...)
842 panic("Log in goroutine after " + c.name + " has completed: " + s)
846 // Benchmarks don't print === CONT, so we should skip the test
847 // printer and just print straight to stdout.
848 fmt.Print(c.decorate(s, depth+1))
850 c.chatty.Printf(c.name, "%s", c.decorate(s, depth+1))
855 c.output = append(c.output, c.decorate(s, depth+1)...)
859 // Log formats its arguments using default formatting, analogous to Println,
860 // and records the text in the error log. For tests, the text will be printed only if
861 // the test fails or the -test.v flag is set. For benchmarks, the text is always
862 // printed to avoid having performance depend on the value of the -test.v flag.
863 func (c *common) Log(args ...interface{}) { c.log(fmt.Sprintln(args...)) }
865 // Logf formats its arguments according to the format, analogous to Printf, and
866 // records the text in the error log. A final newline is added if not provided. For
867 // tests, the text will be printed only if the test fails or the -test.v flag is
868 // set. For benchmarks, the text is always printed to avoid having performance
869 // depend on the value of the -test.v flag.
870 func (c *common) Logf(format string, args ...interface{}) { c.log(fmt.Sprintf(format, args...)) }
872 // Error is equivalent to Log followed by Fail.
873 func (c *common) Error(args ...interface{}) {
874 c.log(fmt.Sprintln(args...))
878 // Errorf is equivalent to Logf followed by Fail.
879 func (c *common) Errorf(format string, args ...interface{}) {
880 c.log(fmt.Sprintf(format, args...))
884 // Fatal is equivalent to Log followed by FailNow.
885 func (c *common) Fatal(args ...interface{}) {
886 c.log(fmt.Sprintln(args...))
890 // Fatalf is equivalent to Logf followed by FailNow.
891 func (c *common) Fatalf(format string, args ...interface{}) {
892 c.log(fmt.Sprintf(format, args...))
896 // Skip is equivalent to Log followed by SkipNow.
897 func (c *common) Skip(args ...interface{}) {
898 c.log(fmt.Sprintln(args...))
902 // Skipf is equivalent to Logf followed by SkipNow.
903 func (c *common) Skipf(format string, args ...interface{}) {
904 c.log(fmt.Sprintf(format, args...))
908 // SkipNow marks the test as having been skipped and stops its execution
909 // by calling runtime.Goexit.
910 // If a test fails (see Error, Errorf, Fail) and is then skipped,
911 // it is still considered to have failed.
912 // Execution will continue at the next test or benchmark. See also FailNow.
913 // SkipNow must be called from the goroutine running the test, not from
914 // other goroutines created during the test. Calling SkipNow does not stop
915 // those other goroutines.
916 func (c *common) SkipNow() {
924 // Skipped reports whether the test was skipped.
925 func (c *common) Skipped() bool {
931 // Helper marks the calling function as a test helper function.
932 // When printing file and line information, that function will be skipped.
933 // Helper may be called simultaneously from multiple goroutines.
934 func (c *common) Helper() {
937 if c.helperPCs == nil {
938 c.helperPCs = make(map[uintptr]struct{})
940 // repeating code from callerName here to save walking a stack frame
942 n := runtime.Callers(2, pc[:]) // skip runtime.Callers + Helper
944 panic("testing: zero callers found")
946 if _, found := c.helperPCs[pc[0]]; !found {
947 c.helperPCs[pc[0]] = struct{}{}
948 c.helperNames = nil // map will be recreated next time it is needed
952 // Cleanup registers a function to be called when the test (or subtest) and all its
953 // subtests complete. Cleanup functions will be called in last added,
954 // first called order.
955 func (c *common) Cleanup(f func()) {
956 var pc [maxStackLen]uintptr
957 // Skip two extra frames to account for this function and runtime.Callers itself.
958 n := runtime.Callers(2, pc[:])
969 name := callerName(0)
972 c.cleanupPc = cleanupPc
980 c.cleanups = append(c.cleanups, fn)
983 // TempDir returns a temporary directory for the test to use.
984 // The directory is automatically removed by Cleanup when the test and
985 // all its subtests complete.
986 // Each subsequent call to t.TempDir returns a unique directory;
987 // if the directory creation fails, TempDir terminates the test by calling Fatal.
988 func (c *common) TempDir() string {
989 // Use a single parent directory for all the temporary directories
990 // created by a test, each numbered sequentially.
993 if c.tempDir == "" { // Usually the case with js/wasm
996 _, err := os.Stat(c.tempDir)
997 nonExistent = os.IsNotExist(err)
998 if err != nil && !nonExistent {
999 c.Fatalf("TempDir: %v", err)
1006 // Drop unusual characters (such as path separators or
1007 // characters interacting with globs) from the directory name to
1008 // avoid surprising os.MkdirTemp behavior.
1009 mapper := func(r rune) rune {
1010 if r < utf8.RuneSelf {
1011 const allowed = "!#$%&()+,-.=@^_{}~ "
1012 if '0' <= r && r <= '9' ||
1013 'a' <= r && r <= 'z' ||
1014 'A' <= r && r <= 'Z' {
1017 if strings.ContainsRune(allowed, r) {
1020 } else if unicode.IsLetter(r) || unicode.IsNumber(r) {
1025 pattern := strings.Map(mapper, c.Name())
1026 c.tempDir, c.tempDirErr = os.MkdirTemp("", pattern)
1027 if c.tempDirErr == nil {
1029 if err := os.RemoveAll(c.tempDir); err != nil {
1030 c.Errorf("TempDir RemoveAll cleanup: %v", err)
1035 c.tempDirMu.Unlock()
1037 if c.tempDirErr != nil {
1038 c.Fatalf("TempDir: %v", c.tempDirErr)
1040 seq := atomic.AddInt32(&c.tempDirSeq, 1)
1041 dir := fmt.Sprintf("%s%c%03d", c.tempDir, os.PathSeparator, seq)
1042 if err := os.Mkdir(dir, 0777); err != nil {
1043 c.Fatalf("TempDir: %v", err)
1048 // Setenv calls os.Setenv(key, value) and uses Cleanup to
1049 // restore the environment variable to its original value
1052 // This cannot be used in parallel tests.
1053 func (c *common) Setenv(key, value string) {
1054 prevValue, ok := os.LookupEnv(key)
1056 if err := os.Setenv(key, value); err != nil {
1057 c.Fatalf("cannot set environment variable: %v", err)
1062 os.Setenv(key, prevValue)
1071 // panicHanding is an argument to runCleanup.
1072 type panicHandling int
1075 normalPanic panicHandling = iota
1076 recoverAndReturnPanic
1079 // runCleanup is called at the end of the test.
1080 // If catchPanic is true, this will catch panics, and return the recovered
1082 func (c *common) runCleanup(ph panicHandling) (panicVal interface{}) {
1083 if ph == recoverAndReturnPanic {
1085 panicVal = recover()
1089 // Make sure that if a cleanup function panics,
1090 // we still run the remaining cleanup functions.
1093 recur := len(c.cleanups) > 0
1096 c.runCleanup(normalPanic)
1103 if len(c.cleanups) > 0 {
1104 last := len(c.cleanups) - 1
1105 cleanup = c.cleanups[last]
1106 c.cleanups = c.cleanups[:last]
1116 // callerName gives the function name (qualified with a package path)
1117 // for the caller after skip frames (where 0 means the current function).
1118 func callerName(skip int) string {
1120 n := runtime.Callers(skip+2, pc[:]) // skip + runtime.Callers + callerName
1122 panic("testing: zero callers found")
1124 return pcToName(pc[0])
1127 func pcToName(pc uintptr) string {
1128 pcs := []uintptr{pc}
1129 frames := runtime.CallersFrames(pcs)
1130 frame, _ := frames.Next()
1131 return frame.Function
1134 // Parallel signals that this test is to be run in parallel with (and only with)
1135 // other parallel tests. When a test is run multiple times due to use of
1136 // -test.count or -test.cpu, multiple instances of a single test never run in
1137 // parallel with each other.
1138 func (t *T) Parallel() {
1140 panic("testing: t.Parallel called multiple times")
1143 panic("testing: t.Parallel called after t.Setenv; cannot set environment variables in parallel tests")
1146 if t.parent.barrier == nil {
1147 // T.Parallel has no effect when fuzzing.
1148 // Multiple processes may run in parallel, but only one input can run at a
1149 // time per process so we can attribute crashes to specific inputs.
1153 // We don't want to include the time we spend waiting for serial tests
1154 // in the test duration. Record the elapsed time thus far and reset the
1155 // timer afterwards.
1156 t.duration += time.Since(t.start)
1158 // Add to the list of tests to be released by the parent.
1159 t.parent.sub = append(t.parent.sub, t)
1160 t.raceErrors += race.Errors()
1162 if t.chatty != nil {
1163 // Unfortunately, even though PAUSE indicates that the named test is *no
1164 // longer* running, cmd/test2json interprets it as changing the active test
1165 // for the purpose of log parsing. We could fix cmd/test2json, but that
1166 // won't fix existing deployments of third-party tools that already shell
1167 // out to older builds of cmd/test2json — so merely fixing cmd/test2json
1168 // isn't enough for now.
1169 t.chatty.Updatef(t.name, "=== PAUSE %s\n", t.name)
1172 t.signal <- true // Release calling test.
1173 <-t.parent.barrier // Wait for the parent test to complete.
1174 t.context.waitParallel()
1176 if t.chatty != nil {
1177 t.chatty.Updatef(t.name, "=== CONT %s\n", t.name)
1180 t.start = time.Now()
1181 t.raceErrors += -race.Errors()
1184 // Setenv calls os.Setenv(key, value) and uses Cleanup to
1185 // restore the environment variable to its original value
1188 // This cannot be used in parallel tests.
1189 func (t *T) Setenv(key, value string) {
1191 panic("testing: t.Setenv called after t.Parallel; cannot set environment variables in parallel tests")
1196 t.common.Setenv(key, value)
1199 // InternalTest is an internal type but exported because it is cross-package;
1200 // it is part of the implementation of the "go test" command.
1201 type InternalTest struct {
1206 var errNilPanicOrGoexit = errors.New("test executed panic(nil) or runtime.Goexit")
1208 func tRunner(t *T, fn func(t *T)) {
1209 t.runner = callerName(0)
1211 // When this goroutine is done, either because fn(t)
1212 // returned normally or because a test failure triggered
1213 // a call to runtime.Goexit, record the duration and send
1214 // a signal saying that the test is done.
1217 atomic.AddUint32(&numFailed, 1)
1220 if t.raceErrors+race.Errors() > 0 {
1221 t.Errorf("race detected during execution of test")
1224 // If the test panicked, print any test output before dying.
1229 finished := t.finished
1231 if !finished && err == nil {
1232 err = errNilPanicOrGoexit
1233 for p := t.parent; p != nil; p = p.parent {
1235 finished = p.finished
1238 t.Errorf("%v: subtest may have called FailNow on a parent test", err)
1245 // Use a deferred call to ensure that we report that the test is
1246 // complete even if a cleanup function calls t.FailNow. See issue 41355.
1249 isFuzzing := t.common.isFuzzing()
1250 if didPanic && !isFuzzing {
1253 if err != nil && !isFuzzing {
1256 // Only report that the test is complete if it doesn't panic,
1257 // as otherwise the test binary can exit before the panic is
1258 // reported to the user. See issue 41479.
1262 doPanic := func(err interface{}) {
1264 if r := t.runCleanup(recoverAndReturnPanic); r != nil {
1265 t.Logf("cleanup panicked with %v", r)
1267 // Flush the output log up to the root before dying.
1268 for root := &t.common; root.parent != nil; root = root.parent {
1270 root.duration += time.Since(root.start)
1273 root.flushToParent(root.name, "--- FAIL: %s (%s)\n", root.name, fmtDuration(d))
1274 if r := root.parent.runCleanup(recoverAndReturnPanic); r != nil {
1275 fmt.Fprintf(root.parent.w, "cleanup panicked with %v", r)
1279 if t.common.fuzzing {
1280 for root := &t.common; root.parent != nil; root = root.parent {
1281 fmt.Fprintf(root.parent.w, "panic: %s\n%s\n", err, string(debug.Stack()))
1291 t.duration += time.Since(t.start)
1294 // Run parallel subtests.
1295 // Decrease the running count for this test.
1297 // Release the parallel subtests.
1299 // Wait for subtests to complete.
1300 for _, sub := range t.sub {
1303 cleanupStart := time.Now()
1304 err := t.runCleanup(recoverAndReturnPanic)
1305 t.duration += time.Since(cleanupStart)
1310 // Reacquire the count for sequential tests. See comment in Run.
1311 t.context.waitParallel()
1313 } else if t.isParallel {
1314 // Only release the count for this test if it was run as a parallel
1315 // test. See comment in Run method.
1318 t.report() // Report after all subtests have finished.
1320 // Do not lock t.done to allow race detector to detect race in case
1321 // the user does not appropriately synchronizes a goroutine.
1323 if t.parent != nil && atomic.LoadInt32(&t.hasSub) == 0 {
1328 if len(t.sub) == 0 {
1329 t.runCleanup(normalPanic)
1333 t.start = time.Now()
1334 t.raceErrors = -race.Errors()
1337 // code beyond here will not be executed when FailNow is invoked
1343 // Run runs f as a subtest of t called name. It runs f in a separate goroutine
1344 // and blocks until f returns or calls t.Parallel to become a parallel test.
1345 // Run reports whether f succeeded (or at least did not fail before calling t.Parallel).
1347 // Run may be called simultaneously from multiple goroutines, but all such calls
1348 // must return before the outer test function for t returns.
1349 func (t *T) Run(name string, f func(t *T)) bool {
1350 atomic.StoreInt32(&t.hasSub, 1)
1351 testName, ok, _ := t.context.match.fullName(&t.common, name)
1352 if !ok || shouldFailFast() {
1355 // Record the stack trace at the point of this call so that if the subtest
1356 // function - which runs in a separate stack - is marked as a helper, we can
1357 // continue walking the stack into the parent test.
1358 var pc [maxStackLen]uintptr
1359 n := runtime.Callers(2, pc[:])
1362 barrier: make(chan bool),
1363 signal: make(chan bool, 1),
1372 t.w = indenter{&t.common}
1374 if t.chatty != nil {
1375 t.chatty.Updatef(t.name, "=== RUN %s\n", t.name)
1377 // Instead of reducing the running count of this test before calling the
1378 // tRunner and increasing it afterwards, we rely on tRunner keeping the
1379 // count correct. This ensures that a sequence of sequential tests runs
1380 // without being preempted, even when their parent is a parallel test. This
1381 // may especially reduce surprises if *parallel == 1.
1384 // At this point, it is likely that FailNow was called on one of the
1385 // parent tests by one of the subtests. Continue aborting up the chain.
1391 // Deadline reports the time at which the test binary will have
1392 // exceeded the timeout specified by the -timeout flag.
1394 // The ok result is false if the -timeout flag indicates “no timeout” (0).
1395 func (t *T) Deadline() (deadline time.Time, ok bool) {
1396 deadline = t.context.deadline
1397 return deadline, !deadline.IsZero()
1400 // testContext holds all fields that are common to all tests. This includes
1401 // synchronization primitives to run at most *parallel tests.
1402 type testContext struct {
1408 // Channel used to signal tests that are ready to be run in parallel.
1409 startParallel chan bool
1411 // running is the number of tests currently running in parallel.
1412 // This does not include tests that are waiting for subtests to complete.
1415 // numWaiting is the number tests waiting to be run in parallel.
1418 // maxParallel is a copy of the parallel flag.
1422 func newTestContext(maxParallel int, m *matcher) *testContext {
1423 return &testContext{
1425 startParallel: make(chan bool),
1426 maxParallel: maxParallel,
1427 running: 1, // Set the count to 1 for the main (sequential) test.
1431 func (c *testContext) waitParallel() {
1433 if c.running < c.maxParallel {
1443 func (c *testContext) release() {
1445 if c.numWaiting == 0 {
1452 c.startParallel <- true // Pick a waiting test to be run.
1455 // No one should be using func Main anymore.
1456 // See the doc comment on func Main and use MainStart instead.
1457 var errMain = errors.New("testing: unexpected use of func Main")
1459 type matchStringOnly func(pat, str string) (bool, error)
1461 func (f matchStringOnly) MatchString(pat, str string) (bool, error) { return f(pat, str) }
1462 func (f matchStringOnly) StartCPUProfile(w io.Writer) error { return errMain }
1463 func (f matchStringOnly) StopCPUProfile() {}
1464 func (f matchStringOnly) WriteProfileTo(string, io.Writer, int) error { return errMain }
1465 func (f matchStringOnly) ImportPath() string { return "" }
1466 func (f matchStringOnly) StartTestLog(io.Writer) {}
1467 func (f matchStringOnly) StopTestLog() error { return errMain }
1468 func (f matchStringOnly) SetPanicOnExit0(bool) {}
1469 func (f matchStringOnly) CoordinateFuzzing(time.Duration, int64, time.Duration, int64, int, []corpusEntry, []reflect.Type, string, string) error {
1472 func (f matchStringOnly) RunFuzzWorker(func(corpusEntry) error) error { return errMain }
1473 func (f matchStringOnly) ReadCorpus(string, []reflect.Type) ([]corpusEntry, error) {
1476 func (f matchStringOnly) CheckCorpus([]interface{}, []reflect.Type) error { return nil }
1477 func (f matchStringOnly) ResetCoverage() {}
1478 func (f matchStringOnly) SnapshotCoverage() {}
1480 // Main is an internal function, part of the implementation of the "go test" command.
1481 // It was exported because it is cross-package and predates "internal" packages.
1482 // It is no longer used by "go test" but preserved, as much as possible, for other
1483 // systems that simulate "go test" using Main, but Main sometimes cannot be updated as
1484 // new functionality is added to the testing package.
1485 // Systems simulating "go test" should be updated to use MainStart.
1486 func Main(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
1487 os.Exit(MainStart(matchStringOnly(matchString), tests, benchmarks, nil, examples).Run())
1490 // M is a type passed to a TestMain function to run the actual tests.
1493 tests []InternalTest
1494 benchmarks []InternalBenchmark
1495 fuzzTargets []InternalFuzzTarget
1496 examples []InternalExample
1503 // value to pass to os.Exit, the outer test func main
1504 // harness calls os.Exit with this code. See #34129.
1508 // testDeps is an internal interface of functionality that is
1509 // passed into this package by a test's generated main package.
1510 // The canonical implementation of this interface is
1511 // testing/internal/testdeps's TestDeps.
1512 type testDeps interface {
1514 MatchString(pat, str string) (bool, error)
1515 SetPanicOnExit0(bool)
1516 StartCPUProfile(io.Writer) error
1518 StartTestLog(io.Writer)
1520 WriteProfileTo(string, io.Writer, int) error
1521 CoordinateFuzzing(time.Duration, int64, time.Duration, int64, int, []corpusEntry, []reflect.Type, string, string) error
1522 RunFuzzWorker(func(corpusEntry) error) error
1523 ReadCorpus(string, []reflect.Type) ([]corpusEntry, error)
1524 CheckCorpus([]interface{}, []reflect.Type) error
1529 // MainStart is meant for use by tests generated by 'go test'.
1530 // It is not meant to be called directly and is not subject to the Go 1 compatibility document.
1531 // It may change signature from release to release.
1532 func MainStart(deps testDeps, tests []InternalTest, benchmarks []InternalBenchmark, fuzzTargets []InternalFuzzTarget, examples []InternalExample) *M {
1537 benchmarks: benchmarks,
1538 fuzzTargets: fuzzTargets,
1543 // Run runs the tests. It returns an exit code to pass to os.Exit.
1544 func (m *M) Run() (code int) {
1549 // Count the number of calls to m.Run.
1550 // We only ever expected 1, but we didn't enforce that,
1551 // and now there are tests in the wild that call m.Run multiple times.
1552 // Sigh. golang.org/issue/23129.
1555 // TestMain may have already called flag.Parse.
1561 fmt.Fprintln(os.Stderr, "testing: -parallel can only be given a positive integer")
1566 if *matchFuzz != "" && *fuzzCacheDir == "" {
1567 fmt.Fprintln(os.Stderr, "testing: internal error: -test.fuzzcachedir must be set if -test.fuzz is set")
1573 if len(*matchList) != 0 {
1574 listTests(m.deps.MatchString, m.tests, m.benchmarks, m.fuzzTargets, m.examples)
1579 if *shuffle != "off" {
1582 if *shuffle == "on" {
1583 n = time.Now().UnixNano()
1585 n, err = strconv.ParseInt(*shuffle, 10, 64)
1587 fmt.Fprintln(os.Stderr, `testing: -shuffle should be "off", "on", or a valid integer:`, err)
1592 fmt.Println("-test.shuffle", n)
1593 rng := rand.New(rand.NewSource(n))
1594 rng.Shuffle(len(m.tests), func(i, j int) { m.tests[i], m.tests[j] = m.tests[j], m.tests[i] })
1595 rng.Shuffle(len(m.benchmarks), func(i, j int) { m.benchmarks[i], m.benchmarks[j] = m.benchmarks[j], m.benchmarks[i] })
1603 // The fuzzing coordinator will already run all tests, examples,
1604 // and benchmarks. Don't make the workers do redundant work.
1605 deadline := m.startAlarm()
1606 haveExamples = len(m.examples) > 0
1607 testRan, testOk := runTests(m.deps.MatchString, m.tests, deadline)
1608 fuzzTargetsRan, fuzzTargetsOk := runFuzzTargets(m.deps, m.fuzzTargets, deadline)
1609 exampleRan, exampleOk := runExamples(m.deps.MatchString, m.examples)
1611 if !testRan && !exampleRan && !fuzzTargetsRan && *matchBenchmarks == "" && *matchFuzz == "" {
1612 fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
1614 if !testOk || !exampleOk || !fuzzTargetsOk || !runBenchmarks(m.deps.ImportPath(), m.deps.MatchString, m.benchmarks) || race.Errors() > 0 {
1621 fuzzingRan, fuzzingOk := runFuzzing(m.deps, m.fuzzTargets)
1622 if *matchFuzz != "" && !fuzzingRan {
1623 fmt.Fprintln(os.Stderr, "testing: warning: no targets to fuzz")
1625 if !*isFuzzWorker && !fuzzingOk {
1628 m.exitCode = fuzzWorkerExitCode
1642 func (t *T) report() {
1643 if t.parent == nil {
1646 dstr := fmtDuration(t.duration)
1647 format := "--- %s: %s (%s)\n"
1649 t.flushToParent(t.name, format, "FAIL", t.name, dstr)
1650 } else if t.chatty != nil {
1652 t.flushToParent(t.name, format, "SKIP", t.name, dstr)
1654 t.flushToParent(t.name, format, "PASS", t.name, dstr)
1659 func listTests(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, fuzzTargets []InternalFuzzTarget, examples []InternalExample) {
1660 if _, err := matchString(*matchList, "non-empty"); err != nil {
1661 fmt.Fprintf(os.Stderr, "testing: invalid regexp in -test.list (%q): %s\n", *matchList, err)
1665 for _, test := range tests {
1666 if ok, _ := matchString(*matchList, test.Name); ok {
1667 fmt.Println(test.Name)
1670 for _, bench := range benchmarks {
1671 if ok, _ := matchString(*matchList, bench.Name); ok {
1672 fmt.Println(bench.Name)
1675 for _, fuzzTarget := range fuzzTargets {
1676 if ok, _ := matchString(*matchList, fuzzTarget.Name); ok {
1677 fmt.Println(fuzzTarget.Name)
1680 for _, example := range examples {
1681 if ok, _ := matchString(*matchList, example.Name); ok {
1682 fmt.Println(example.Name)
1687 // RunTests is an internal function but exported because it is cross-package;
1688 // it is part of the implementation of the "go test" command.
1689 func RunTests(matchString func(pat, str string) (bool, error), tests []InternalTest) (ok bool) {
1690 var deadline time.Time
1692 deadline = time.Now().Add(*timeout)
1694 ran, ok := runTests(matchString, tests, deadline)
1695 if !ran && !haveExamples {
1696 fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
1701 func runTests(matchString func(pat, str string) (bool, error), tests []InternalTest, deadline time.Time) (ran, ok bool) {
1703 for _, procs := range cpuList {
1704 runtime.GOMAXPROCS(procs)
1705 for i := uint(0); i < *count; i++ {
1706 if shouldFailFast() {
1709 ctx := newTestContext(*parallel, newMatcher(matchString, *match, "-test.run"))
1710 ctx.deadline = deadline
1713 signal: make(chan bool, 1),
1714 barrier: make(chan bool),
1720 t.chatty = newChattyPrinter(t.w)
1722 tRunner(t, func(t *T) {
1723 for _, test := range tests {
1724 t.Run(test.Name, test.F)
1730 panic("internal error: tRunner exited without sending on t.signal")
1732 ok = ok && !t.Failed()
1739 // before runs before all testing.
1740 func (m *M) before() {
1741 if *memProfileRate > 0 {
1742 runtime.MemProfileRate = *memProfileRate
1744 if *cpuProfile != "" {
1745 f, err := os.Create(toOutputDir(*cpuProfile))
1747 fmt.Fprintf(os.Stderr, "testing: %s\n", err)
1750 if err := m.deps.StartCPUProfile(f); err != nil {
1751 fmt.Fprintf(os.Stderr, "testing: can't start cpu profile: %s\n", err)
1755 // Could save f so after can call f.Close; not worth the effort.
1757 if *traceFile != "" {
1758 f, err := os.Create(toOutputDir(*traceFile))
1760 fmt.Fprintf(os.Stderr, "testing: %s\n", err)
1763 if err := trace.Start(f); err != nil {
1764 fmt.Fprintf(os.Stderr, "testing: can't start tracing: %s\n", err)
1768 // Could save f so after can call f.Close; not worth the effort.
1770 if *blockProfile != "" && *blockProfileRate >= 0 {
1771 runtime.SetBlockProfileRate(*blockProfileRate)
1773 if *mutexProfile != "" && *mutexProfileFraction >= 0 {
1774 runtime.SetMutexProfileFraction(*mutexProfileFraction)
1776 if *coverProfile != "" && cover.Mode == "" {
1777 fmt.Fprintf(os.Stderr, "testing: cannot use -test.coverprofile because test binary was not built with coverage enabled\n")
1781 // Note: Not using toOutputDir.
1782 // This file is for use by cmd/go, not users.
1786 f, err = os.Create(*testlog)
1788 f, err = os.OpenFile(*testlog, os.O_WRONLY, 0)
1790 f.Seek(0, io.SeekEnd)
1794 fmt.Fprintf(os.Stderr, "testing: %s\n", err)
1797 m.deps.StartTestLog(f)
1801 m.deps.SetPanicOnExit0(true)
1805 // after runs after all testing.
1806 func (m *M) after() {
1807 m.afterOnce.Do(func() {
1811 // Restore PanicOnExit0 after every run, because we set it to true before
1812 // every run. Otherwise, if m.Run is called multiple times the behavior of
1813 // os.Exit(0) will not be restored after the second run.
1815 m.deps.SetPanicOnExit0(false)
1819 func (m *M) writeProfiles() {
1821 if err := m.deps.StopTestLog(); err != nil {
1822 fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, err)
1825 if err := testlogFile.Close(); err != nil {
1826 fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, err)
1830 if *cpuProfile != "" {
1831 m.deps.StopCPUProfile() // flushes profile to disk
1833 if *traceFile != "" {
1834 trace.Stop() // flushes trace to disk
1836 if *memProfile != "" {
1837 f, err := os.Create(toOutputDir(*memProfile))
1839 fmt.Fprintf(os.Stderr, "testing: %s\n", err)
1842 runtime.GC() // materialize all statistics
1843 if err = m.deps.WriteProfileTo("allocs", f, 0); err != nil {
1844 fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *memProfile, err)
1849 if *blockProfile != "" && *blockProfileRate >= 0 {
1850 f, err := os.Create(toOutputDir(*blockProfile))
1852 fmt.Fprintf(os.Stderr, "testing: %s\n", err)
1855 if err = m.deps.WriteProfileTo("block", f, 0); err != nil {
1856 fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *blockProfile, err)
1861 if *mutexProfile != "" && *mutexProfileFraction >= 0 {
1862 f, err := os.Create(toOutputDir(*mutexProfile))
1864 fmt.Fprintf(os.Stderr, "testing: %s\n", err)
1867 if err = m.deps.WriteProfileTo("mutex", f, 0); err != nil {
1868 fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *mutexProfile, err)
1873 if cover.Mode != "" {
1878 // toOutputDir returns the file name relocated, if required, to outputDir.
1879 // Simple implementation to avoid pulling in path/filepath.
1880 func toOutputDir(path string) string {
1881 if *outputDir == "" || path == "" {
1884 // On Windows, it's clumsy, but we can be almost always correct
1885 // by just looking for a drive letter and a colon.
1886 // Absolute paths always have a drive letter (ignoring UNC).
1887 // Problem: if path == "C:A" and outputdir == "C:\Go" it's unclear
1888 // what to do, but even then path/filepath doesn't help.
1889 // TODO: Worth doing better? Probably not, because we're here only
1890 // under the management of go test.
1891 if runtime.GOOS == "windows" && len(path) >= 2 {
1892 letter, colon := path[0], path[1]
1893 if ('a' <= letter && letter <= 'z' || 'A' <= letter && letter <= 'Z') && colon == ':' {
1894 // If path starts with a drive letter we're stuck with it regardless.
1898 if os.IsPathSeparator(path[0]) {
1901 return fmt.Sprintf("%s%c%s", *outputDir, os.PathSeparator, path)
1904 // startAlarm starts an alarm if requested.
1905 func (m *M) startAlarm() time.Time {
1910 deadline := time.Now().Add(*timeout)
1911 m.timer = time.AfterFunc(*timeout, func() {
1913 debug.SetTraceback("all")
1914 panic(fmt.Sprintf("test timed out after %v", *timeout))
1919 // stopAlarm turns off the alarm.
1920 func (m *M) stopAlarm() {
1926 func parseCpuList() {
1927 for _, val := range strings.Split(*cpuListStr, ",") {
1928 val = strings.TrimSpace(val)
1932 cpu, err := strconv.Atoi(val)
1933 if err != nil || cpu <= 0 {
1934 fmt.Fprintf(os.Stderr, "testing: invalid value %q for -test.cpu\n", val)
1937 cpuList = append(cpuList, cpu)
1940 cpuList = append(cpuList, runtime.GOMAXPROCS(-1))
1944 func shouldFailFast() bool {
1945 return *failFast && atomic.LoadUint32(&numFailed) > 0