// 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 does not start with a lowercase letter. The function name // 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". // // A simple test function looks like this: // // func TestAbs(t *testing.T) { // got := Abs(-1) // if got != 1 { // t.Errorf("Abs(-1) = %d; want 1", got) // } // } // // 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-Testing_flags // // A sample benchmark function looks like this: // func BenchmarkRandInt(b *testing.B) { // for i := 0; i < b.N; i++ { // rand.Int() // } // } // // 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 // BenchmarkRandInt-8 68453040 17.8 ns/op // means that the loop ran 68453040 times at a speed of 17.8 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 // } // // The comment prefix "Unordered output:" is like "Output:", but matches any // line order: // // func ExamplePerm() { // for _, value := range Perm(5) { // fmt.Println(value) // } // // Unordered output: 4 // // 2 // // 1 // // 3 // // 0 // } // // 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. // // Skipping // // Tests or benchmarks may be skipped at run time with a call to // the Skip method of *T or *B: // // func TestTimeConsuming(t *testing.T) { // if testing.Short() { // t.Skip("skipping test in short mode.") // } // ... // } // // Subtests and Sub-benchmarks // // The Run methods of T and B allow defining subtests and sub-benchmarks, // without having to define separate functions for each. This enables uses // like table-driven benchmarks and creating hierarchical tests. // It also provides a way to share common setup and tear-down code: // // func TestFoo(t *testing.T) { // // <setup code> // t.Run("A=1", func(t *testing.T) { ... }) // t.Run("A=2", func(t *testing.T) { ... }) // t.Run("B=1", func(t *testing.T) { ... }) // // <tear-down code> // } // // Each subtest and sub-benchmark has a unique name: the combination of the name // of the top-level test and the sequence of names passed to Run, separated by // slashes, with an optional trailing sequence number for disambiguation. // // The argument to the -run and -bench command-line flags is an unanchored regular // expression that matches the test's name. For tests with multiple slash-separated // elements, such as subtests, the argument is itself slash-separated, with // expressions matching each name element in turn. Because it is unanchored, an // empty expression matches any string. // For example, using "matching" to mean "whose name contains": // // go test -run '' # Run all tests. // go test -run Foo # Run top-level tests matching "Foo", such as "TestFooBar". // go test -run Foo/A= # For top-level tests matching "Foo", run subtests matching "A=". // go test -run /A=1 # For all top-level tests, run subtests matching "A=1". // // Subtests can also be used to control parallelism. A parent test will only // complete once all of its subtests complete. In this example, all tests are // run in parallel with each other, and only with each other, regardless of // other top-level tests that may be defined: // // func TestGroupedParallel(t *testing.T) { // for _, tc := range tests { // tc := tc // capture range variable // t.Run(tc.Name, func(t *testing.T) { // t.Parallel() // ... // }) // } // } // // The race detector kills the program if it exceeds 8192 concurrent goroutines, // so use care when running parallel tests with the -race flag set. // // Run does not return until parallel subtests have completed, providing a way // to clean up after a group of parallel tests: // // func TestTeardownParallel(t *testing.T) { // // This Run will not return until the parallel tests finish. // t.Run("group", func(t *testing.T) { // t.Run("Test1", parallelTest1) // t.Run("Test2", parallelTest2) // t.Run("Test3", parallelTest3) // }) // // <tear-down code> // } // // 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. m.Run will return an exit // code that may be passed to os.Exit. If TestMain returns, the test wrapper // will pass the result of m.Run to os.Exit itself. // // 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. Command line flags are always parsed by the time test // or benchmark functions run. // // A simple implementation of TestMain is: // // func TestMain(m *testing.M) { // // call flag.Parse() here if TestMain uses flags // os.Exit(m.Run()) // } //
package testing import ( ) var initRan bool // Init registers testing flags. These flags are automatically registered by // the "go test" command before running test functions, so Init is only needed // when calling functions such as Benchmark without using "go test". // // Init has no effect if it was already called. func () { if initRan { return } initRan = true // 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 failfast flag requests that test execution stop after the first test failure. failFast = flag.Bool("test.failfast", false, "do not start new tests after the first test failure") // 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", "", "write profiles to `dir`") // 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 `file`") matchList = flag.String("test.list", "", "list tests, examples, and benchmarks matching `regexp` then exit") match = flag.String("test.run", "", "run only tests and examples matching `regexp`") memProfile = flag.String("test.memprofile", "", "write an allocation profile to `file`") memProfileRate = flag.Int("test.memprofilerate", 0, "set memory allocation profiling `rate` (see runtime.MemProfileRate)") cpuProfile = flag.String("test.cpuprofile", "", "write a cpu profile to `file`") blockProfile = flag.String("test.blockprofile", "", "write a goroutine blocking profile to `file`") blockProfileRate = flag.Int("test.blockprofilerate", 1, "set blocking profile `rate` (see runtime.SetBlockProfileRate)") mutexProfile = flag.String("test.mutexprofile", "", "write a mutex contention profile to the named file after execution") mutexProfileFraction = flag.Int("test.mutexprofilefraction", 1, "if >= 0, calls runtime.SetMutexProfileFraction()") panicOnExit0 = flag.Bool("test.paniconexit0", false, "panic on call to os.Exit(0)") traceFile = flag.String("test.trace", "", "write an execution trace to `file`") timeout = flag.Duration("test.timeout", 0, "panic test binary after duration `d` (default 0, timeout disabled)") cpuListStr = flag.String("test.cpu", "", "comma-separated `list` of cpu counts to run each test with") parallel = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "run at most `n` tests in parallel") testlog = flag.String("test.testlogfile", "", "write test action log to `file` (for use only by cmd/go)") initBenchmarkFlags() } var ( // Flags, registered during Init. short *bool failFast *bool outputDir *string chatty *bool count *uint coverProfile *string matchList *string match *string memProfile *string memProfileRate *int cpuProfile *string blockProfile *string blockProfileRate *int mutexProfile *string mutexProfileFraction *int panicOnExit0 *bool traceFile *string timeout *time.Duration cpuListStr *string parallel *int testlog *string haveExamples bool // are there examples? cpuList []int testlogFile *os.File numFailed uint32 // number of test failures ) type chattyPrinter struct { w io.Writer lastNameMu sync.Mutex // guards lastName lastName string // last printed test name in chatty mode } func newChattyPrinter( io.Writer) *chattyPrinter { return &chattyPrinter{w: } } // Updatef prints a message about the status of the named test to w. // // The formatted message must include the test name itself. func ( *chattyPrinter) (, string, ...interface{}) { .lastNameMu.Lock() defer .lastNameMu.Unlock() // Since the message already implies an association with a specific new test, // we don't need to check what the old test name was or log an extra CONT line // for it. (We're updating it anyway, and the current message already includes // the test name.) .lastName = fmt.Fprintf(.w, , ...) } // Printf prints a message, generated by the named test, that does not // necessarily mention that tests's name itself. func ( *chattyPrinter) (, string, ...interface{}) { .lastNameMu.Lock() defer .lastNameMu.Unlock() if .lastName == "" { .lastName = } else if .lastName != { fmt.Fprintf(.w, "=== CONT %s\n", ) .lastName = } fmt.Fprintf(.w, , ...) } // The maximum number of stack frames to go through when skipping helper functions for // the purpose of decorating log messages. const maxStackLen = 50 // common holds the elements common between T and B and // captures common methods such as Errorf. type common struct { mu sync.RWMutex // guards this group of fields output []byte // Output generated by test or benchmark. w io.Writer // For flushToParent. ran bool // Test or benchmark (or one of its subtests) was executed. failed bool // Test or benchmark has failed. skipped bool // Test of benchmark has been skipped. done bool // Test is finished and all subtests have completed. helperPCs map[uintptr]struct{} // functions to be skipped when writing file/line info helperNames map[string]struct{} // helperPCs converted to function names cleanups []func() // optional functions to be called at the end of the test cleanupName string // Name of the cleanup function. cleanupPc []uintptr // The stack trace at the point where Cleanup was called. chatty *chattyPrinter // A copy of chattyPrinter, if the chatty flag is set. bench bool // Whether the current test is a benchmark. finished bool // Test function has completed. hasSub int32 // Written atomically. raceErrors int // Number of races detected during test. runner string // Function name of tRunner running the test. parent *common level int // Nesting depth of test or benchmark. creator []uintptr // If level > 0, the stack trace at the point where the parent called t.Run. name string // Name of test or benchmark. start time.Time // Time test or benchmark started duration time.Duration barrier chan bool // To signal parallel subtests they may start. signal chan bool // To signal a test is done. sub []*T // Queue of subtests to be run in parallel. tempDirMu sync.Mutex tempDir string tempDirErr error tempDirSeq int32 } // Short reports whether the -test.short flag is set. func () bool { if short == nil { panic("testing: Short called before Init") } // Catch code that calls this from TestMain without first calling flag.Parse. if !flag.Parsed() { panic("testing: Short called before Parse") } return *short } // CoverMode reports what the test coverage mode is set to. The // values are "set", "count", or "atomic". The return value will be // empty if test coverage is not enabled. func () string { return cover.Mode } // Verbose reports whether the -test.v flag is set. func () bool { // Same as in Short. if chatty == nil { panic("testing: Verbose called before Init") } if !flag.Parsed() { panic("testing: Verbose called before Parse") } return *chatty } // frameSkip searches, starting after skip frames, for the first caller frame // in a function not marked as a helper and returns that frame. // The search stops if it finds a tRunner function that // was the entry point into the test and the test is not a subtest. // This function must be called with c.mu held. func ( *common) ( int) runtime.Frame { // If the search continues into the parent test, we'll have to hold // its mu temporarily. If we then return, we need to unlock it. := false defer func() { if { .mu.Unlock() } }() var [maxStackLen]uintptr // Skip two extra frames to account for this function // and runtime.Callers itself. := runtime.Callers(+2, [:]) if == 0 { panic("testing: zero callers found") } := runtime.CallersFrames([:]) var , , runtime.Frame for := true; ; = { , = .Next() if .Function == .cleanupName { = runtime.CallersFrames(.cleanupPc) continue } if .PC == 0 { = } if .Function == .runner { // We've gone up all the way to the tRunner calling // the test function (so the user must have // called tb.Helper from inside that test function). // If this is a top-level test, only skip up to the test function itself. // If we're in a subtest, continue searching in the parent test, // starting from the point of the call to Run which created this subtest. if .level > 1 { = runtime.CallersFrames(.creator) := .parent // We're no longer looking at the current c after this point, // so we should unlock its mu, unless it's the original receiver, // in which case our caller doesn't expect us to do that. if { .mu.Unlock() } = // Remember to unlock c.mu when we no longer need it, either // because we went up another nesting level, or because we // returned. = true .mu.Lock() continue } return } if , := .helperNames[.Function]; ! { // Found a frame that wasn't inside a helper function. return } } return } // decorate prefixes the string with the file and line of the call site // and inserts the final newline if needed and indentation spaces for formatting. // This function must be called with c.mu held. func ( *common) ( string, int) string { // If more helper PCs have been added since we last did the conversion if .helperNames == nil { .helperNames = make(map[string]struct{}) for := range .helperPCs { .helperNames[pcToName()] = struct{}{} } } := .frameSkip() := .File := .Line if != "" { // Truncate file name at last file name separator. if := strings.LastIndex(, "/"); >= 0 { = [+1:] } else if = strings.LastIndex(, "\\"); >= 0 { = [+1:] } } else { = "???" } if == 0 { = 1 } := new(strings.Builder) // Every line is indented at least 4 spaces. .WriteString(" ") fmt.Fprintf(, "%s:%d: ", , ) := strings.Split(, "\n") if := len(); > 1 && [-1] == "" { = [:-1] } for , := range { if > 0 { // Second and subsequent lines are indented an additional 4 spaces. .WriteString("\n ") } .WriteString() } .WriteByte('\n') return .String() } // flushToParent writes c.output to the parent after first writing the header // with the given format and arguments. func ( *common) (, string, ...interface{}) { := .parent .mu.Lock() defer .mu.Unlock() .mu.Lock() defer .mu.Unlock() if len(.output) > 0 { += "%s" = append([:len():len()], .output) .output = .output[:0] // but why? } if .chatty != nil && .w == .chatty.w { // We're flushing to the actual output, so track that this output is // associated with a specific test (and, specifically, that the next output // is *not* associated with that test). // // Moreover, if c.output is non-empty it is important that this write be // atomic with respect to the output of other tests, so that we don't end up // with confusing '=== CONT' lines in the middle of our '--- PASS' block. // Neither humans nor cmd/test2json can parse those easily. // (See https://golang.org/issue/40771.) .chatty.Updatef(, , ...) } else { // We're flushing to the output buffer of the parent test, which will // itself follow a test-name header when it is finally flushed to stdout. fmt.Fprintf(.w, , ...) } } type indenter struct { c *common } func ( indenter) ( []byte) ( int, error) { = len() for len() > 0 { := bytes.IndexByte(, '\n') if == -1 { = len() } else { ++ } // An indent of 4 spaces will neatly align the dashes with the status // indicator of the parent. const = " " .c.output = append(.c.output, ...) .c.output = append(.c.output, [:]...) = [:] } return } // fmtDuration returns a string representing d in the form "87.00s". func fmtDuration( time.Duration) string { return fmt.Sprintf("%.2fs", .Seconds()) } // TB is the interface common to T and B. type TB interface { Cleanup(func()) Error(args ...interface{}) Errorf(format string, args ...interface{}) Fail() FailNow() Failed() bool Fatal(args ...interface{}) Fatalf(format string, args ...interface{}) Helper() Log(args ...interface{}) Logf(format string, args ...interface{}) Name() string Skip(args ...interface{}) SkipNow() Skipf(format string, args ...interface{}) Skipped() bool TempDir() string // 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. // // A test ends when its Test function returns or calls any of the methods // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods, as well as // the Parallel method, must be called only from the goroutine running the // Test function. // // The other reporting methods, such as the variations of Log and Error, // may be called simultaneously from multiple goroutines. type T struct { common isParallel bool context *testContext // For running tests and subtests. } func ( *common) () {} // Name returns the name of the running test or benchmark. func ( *common) () string { return .name } func ( *common) () { if .parent != nil { .parent.() } .mu.Lock() defer .mu.Unlock() .ran = true } // Fail marks the function as having failed but continues execution. func ( *common) () { if .parent != nil { .parent.() } .mu.Lock() defer .mu.Unlock() // c.done needs to be locked to synchronize checks to c.done in parent tests. if .done { panic("Fail in goroutine after " + .name + " has completed") } .failed = true } // Failed reports whether the function has failed. func ( *common) () bool { .mu.RLock() := .failed .mu.RUnlock() return || .raceErrors+race.Errors() > 0 } // FailNow marks the function as having failed and stops its execution // by calling runtime.Goexit (which then runs all deferred calls in the // current goroutine). // 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 ( *common) () { .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. .finished = true runtime.Goexit() } // log generates the output. It's always at the same stack depth. func ( *common) ( string) { .logDepth(, 3) // logDepth + log + public function } // logDepth generates the output at an arbitrary stack depth. func ( *common) ( string, int) { .mu.Lock() defer .mu.Unlock() if .done { // This test has already finished. Try and log this message // with our parent. If we don't have a parent, panic. for := .parent; != nil; = .parent { .mu.Lock() defer .mu.Unlock() if !.done { .output = append(.output, .decorate(, +1)...) return } } panic("Log in goroutine after " + .name + " has completed") } else { if .chatty != nil { if .bench { // Benchmarks don't print === CONT, so we should skip the test // printer and just print straight to stdout. fmt.Print(.decorate(, +1)) } else { .chatty.Printf(.name, "%s", .decorate(, +1)) } return } .output = append(.output, .decorate(, +1)...) } } // 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 ( *common) ( ...interface{}) { .log(fmt.Sprintln(...)) } // Logf formats its arguments according to the format, analogous to Printf, and // records the text in the error log. A final newline is added if not provided. 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 ( *common) ( string, ...interface{}) { .log(fmt.Sprintf(, ...)) } // Error is equivalent to Log followed by Fail. func ( *common) ( ...interface{}) { .log(fmt.Sprintln(...)) .Fail() } // Errorf is equivalent to Logf followed by Fail. func ( *common) ( string, ...interface{}) { .log(fmt.Sprintf(, ...)) .Fail() } // Fatal is equivalent to Log followed by FailNow. func ( *common) ( ...interface{}) { .log(fmt.Sprintln(...)) .FailNow() } // Fatalf is equivalent to Logf followed by FailNow. func ( *common) ( string, ...interface{}) { .log(fmt.Sprintf(, ...)) .FailNow() } // Skip is equivalent to Log followed by SkipNow. func ( *common) ( ...interface{}) { .log(fmt.Sprintln(...)) .SkipNow() } // Skipf is equivalent to Logf followed by SkipNow. func ( *common) ( string, ...interface{}) { .log(fmt.Sprintf(, ...)) .SkipNow() } // SkipNow marks the test as having been skipped and stops its execution // by calling runtime.Goexit. // If a test fails (see Error, Errorf, Fail) and is then skipped, // it is still considered to have failed. // 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 ( *common) () { .skip() .finished = true runtime.Goexit() } func ( *common) () { .mu.Lock() defer .mu.Unlock() .skipped = true } // Skipped reports whether the test was skipped. func ( *common) () bool { .mu.RLock() defer .mu.RUnlock() return .skipped } // Helper marks the calling function as a test helper function. // When printing file and line information, that function will be skipped. // Helper may be called simultaneously from multiple goroutines. func ( *common) () { .mu.Lock() defer .mu.Unlock() if .helperPCs == nil { .helperPCs = make(map[uintptr]struct{}) } // repeating code from callerName here to save walking a stack frame var [1]uintptr := runtime.Callers(2, [:]) // skip runtime.Callers + Helper if == 0 { panic("testing: zero callers found") } if , := .helperPCs[[0]]; ! { .helperPCs[[0]] = struct{}{} .helperNames = nil // map will be recreated next time it is needed } } // Cleanup registers a function to be called when the test and all its // subtests complete. Cleanup functions will be called in last added, // first called order. func ( *common) ( func()) { var [maxStackLen]uintptr // Skip two extra frames to account for this function and runtime.Callers itself. := runtime.Callers(2, [:]) := [:] := func() { defer func() { .mu.Lock() defer .mu.Unlock() .cleanupName = "" .cleanupPc = nil }() := callerName(0) .mu.Lock() .cleanupName = .cleanupPc = .mu.Unlock() () } .mu.Lock() defer .mu.Unlock() .cleanups = append(.cleanups, ) } var tempDirReplacer struct { sync.Once r *strings.Replacer } // TempDir returns a temporary directory for the test to use. // The directory is automatically removed by Cleanup when the test and // all its subtests complete. // Each subsequent call to t.TempDir returns a unique directory; // if the directory creation fails, TempDir terminates the test by calling Fatal. func ( *common) () string { // Use a single parent directory for all the temporary directories // created by a test, each numbered sequentially. .tempDirMu.Lock() var bool if .tempDir == "" { // Usually the case with js/wasm = true } else { , := os.Stat(.tempDir) = os.IsNotExist() if != nil && ! { .Fatalf("TempDir: %v", ) } } if { .Helper() // os.MkdirTemp doesn't like path separators in its pattern, // so mangle the name to accommodate subtests. tempDirReplacer.Do(func() { tempDirReplacer.r = strings.NewReplacer("/", "_", "\\", "_", ":", "_") }) := tempDirReplacer.r.Replace(.Name()) .tempDir, .tempDirErr = os.MkdirTemp("", ) if .tempDirErr == nil { .Cleanup(func() { if := os.RemoveAll(.tempDir); != nil { .Errorf("TempDir RemoveAll cleanup: %v", ) } }) } } .tempDirMu.Unlock() if .tempDirErr != nil { .Fatalf("TempDir: %v", .tempDirErr) } := atomic.AddInt32(&.tempDirSeq, 1) := fmt.Sprintf("%s%c%03d", .tempDir, os.PathSeparator, ) if := os.Mkdir(, 0777); != nil { .Fatalf("TempDir: %v", ) } return } // panicHanding is an argument to runCleanup. type panicHandling int const ( normalPanic panicHandling = iota recoverAndReturnPanic ) // runCleanup is called at the end of the test. // If catchPanic is true, this will catch panics, and return the recovered // value if any. func ( *common) ( panicHandling) ( interface{}) { if == recoverAndReturnPanic { defer func() { = recover() }() } // Make sure that if a cleanup function panics, // we still run the remaining cleanup functions. defer func() { .mu.Lock() := len(.cleanups) > 0 .mu.Unlock() if { .(normalPanic) } }() for { var func() .mu.Lock() if len(.cleanups) > 0 { := len(.cleanups) - 1 = .cleanups[] .cleanups = .cleanups[:] } .mu.Unlock() if == nil { return nil } () } } // callerName gives the function name (qualified with a package path) // for the caller after skip frames (where 0 means the current function). func callerName( int) string { var [1]uintptr := runtime.Callers(+2, [:]) // skip + runtime.Callers + callerName if == 0 { panic("testing: zero callers found") } return pcToName([0]) } func pcToName( uintptr) string { := []uintptr{} := runtime.CallersFrames() , := .Next() return .Function } // Parallel signals that this test is to be run in parallel with (and only with) // other parallel tests. When a test is run multiple times due to use of // -test.count or -test.cpu, multiple instances of a single test never run in // parallel with each other. func ( *T) () { if .isParallel { panic("testing: t.Parallel called multiple times") } .isParallel = true // We don't want to include the time we spend waiting for serial tests // in the test duration. Record the elapsed time thus far and reset the // timer afterwards. .duration += time.Since(.start) // Add to the list of tests to be released by the parent. .parent.sub = append(.parent.sub, ) .raceErrors += race.Errors() if .chatty != nil { // Unfortunately, even though PAUSE indicates that the named test is *no // longer* running, cmd/test2json interprets it as changing the active test // for the purpose of log parsing. We could fix cmd/test2json, but that // won't fix existing deployments of third-party tools that already shell // out to older builds of cmd/test2json — so merely fixing cmd/test2json // isn't enough for now. .chatty.Updatef(.name, "=== PAUSE %s\n", .name) } .signal <- true // Release calling test. <-.parent.barrier // Wait for the parent test to complete. .context.waitParallel() if .chatty != nil { .chatty.Updatef(.name, "=== CONT %s\n", .name) } .start = time.Now() .raceErrors += -race.Errors() } // InternalTest is an internal type but exported because it is cross-package; // it is part of the implementation of the "go test" command. type InternalTest struct { Name string F func(*T) } var errNilPanicOrGoexit = errors.New("test executed panic(nil) or runtime.Goexit") func tRunner( *T, func( *T)) { .runner = callerName(0) // When this goroutine is done, either because fn(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() { if .Failed() { atomic.AddUint32(&numFailed, 1) } if .raceErrors+race.Errors() > 0 { .Errorf("race detected during execution of test") } // If the test panicked, print any test output before dying. := recover() := true if !.finished && == nil { = errNilPanicOrGoexit for := .parent; != nil; = .parent { if .finished { .Errorf("%v: subtest may have called FailNow on a parent test", ) = nil = false break } } } // Use a deferred call to ensure that we report that the test is // complete even if a cleanup function calls t.FailNow. See issue 41355. := false defer func() { if { return } if != nil { panic() } // Only report that the test is complete if it doesn't panic, // as otherwise the test binary can exit before the panic is // reported to the user. See issue 41479. .signal <- }() := func( interface{}) { .Fail() if := .runCleanup(recoverAndReturnPanic); != nil { .Logf("cleanup panicked with %v", ) } // Flush the output log up to the root before dying. for := &.common; .parent != nil; = .parent { .mu.Lock() .duration += time.Since(.start) := .duration .mu.Unlock() .flushToParent(.name, "--- FAIL: %s (%s)\n", .name, fmtDuration()) if := .parent.runCleanup(recoverAndReturnPanic); != nil { fmt.Fprintf(.parent.w, "cleanup panicked with %v", ) } } = true panic() } if != nil { () } .duration += time.Since(.start) if len(.sub) > 0 { // Run parallel subtests. // Decrease the running count for this test. .context.release() // Release the parallel subtests. close(.barrier) // Wait for subtests to complete. for , := range .sub { <-.signal } := time.Now() := .runCleanup(recoverAndReturnPanic) .duration += time.Since() if != nil { () } if !.isParallel { // Reacquire the count for sequential tests. See comment in Run. .context.waitParallel() } } else if .isParallel { // Only release the count for this test if it was run as a parallel // test. See comment in Run method. .context.release() } .report() // Report after all subtests have finished. // Do not lock t.done to allow race detector to detect race in case // the user does not appropriately synchronizes a goroutine. .done = true if .parent != nil && atomic.LoadInt32(&.hasSub) == 0 { .setRan() } }() defer func() { if len(.sub) == 0 { .runCleanup(normalPanic) } }() .start = time.Now() .raceErrors = -race.Errors() () // code beyond here will not be executed when FailNow is invoked .finished = true } // Run runs f as a subtest of t called name. It runs f in a separate goroutine // and blocks until f returns or calls t.Parallel to become a parallel test. // Run reports whether f succeeded (or at least did not fail before calling t.Parallel). // // Run may be called simultaneously from multiple goroutines, but all such calls // must return before the outer test function for t returns. func ( *T) ( string, func( *T)) bool { atomic.StoreInt32(&.hasSub, 1) , , := .context.match.fullName(&.common, ) if ! || shouldFailFast() { return true } // Record the stack trace at the point of this call so that if the subtest // function - which runs in a separate stack - is marked as a helper, we can // continue walking the stack into the parent test. var [maxStackLen]uintptr := runtime.Callers(2, [:]) = &T{ common: common{ barrier: make(chan bool), signal: make(chan bool), name: , parent: &.common, level: .level + 1, creator: [:], chatty: .chatty, }, context: .context, } .w = indenter{&.common} if .chatty != nil { .chatty.Updatef(.name, "=== RUN %s\n", .name) } // Instead of reducing the running count of this test before calling the // tRunner and increasing it afterwards, we rely on tRunner keeping the // count correct. This ensures that a sequence of sequential tests runs // without being preempted, even when their parent is a parallel test. This // may especially reduce surprises if *parallel == 1. go tRunner(, ) if !<-.signal { // At this point, it is likely that FailNow was called on one of the // parent tests by one of the subtests. Continue aborting up the chain. runtime.Goexit() } return !.failed } // Deadline reports the time at which the test binary will have // exceeded the timeout specified by the -timeout flag. // // The ok result is false if the -timeout flag indicates “no timeout” (0). func ( *T) () ( time.Time, bool) { = .context.deadline return , !.IsZero() } // testContext holds all fields that are common to all tests. This includes // synchronization primitives to run at most *parallel tests. type testContext struct { match *matcher deadline time.Time mu sync.Mutex // Channel used to signal tests that are ready to be run in parallel. startParallel chan bool // running is the number of tests currently running in parallel. // This does not include tests that are waiting for subtests to complete. running int // numWaiting is the number tests waiting to be run in parallel. numWaiting int // maxParallel is a copy of the parallel flag. maxParallel int } func newTestContext( int, *matcher) *testContext { return &testContext{ match: , startParallel: make(chan bool), maxParallel: , running: 1, // Set the count to 1 for the main (sequential) test. } } func ( *testContext) () { .mu.Lock() if .running < .maxParallel { .running++ .mu.Unlock() return } .numWaiting++ .mu.Unlock() <-.startParallel } func ( *testContext) () { .mu.Lock() if .numWaiting == 0 { .running-- .mu.Unlock() return } .numWaiting-- .mu.Unlock() .startParallel <- true // Pick a waiting test to be run. } // No one should be using func Main anymore. // See the doc comment on func Main and use MainStart instead. var errMain = errors.New("testing: unexpected use of func Main") type matchStringOnly func(pat, str string) (bool, error) func ( matchStringOnly) (, string) (bool, error) { return (, ) } func ( matchStringOnly) ( io.Writer) error { return errMain } func ( matchStringOnly) () {} func ( matchStringOnly) (string, io.Writer, int) error { return errMain } func ( matchStringOnly) () string { return "" } func ( matchStringOnly) (io.Writer) {} func ( matchStringOnly) () error { return errMain } func ( matchStringOnly) (bool) {} // Main is an internal function, part of the implementation of the "go test" command. // It was exported because it is cross-package and predates "internal" packages. // It is no longer used by "go test" but preserved, as much as possible, for other // systems that simulate "go test" using Main, but Main sometimes cannot be updated as // new functionality is added to the testing package. // Systems simulating "go test" should be updated to use MainStart. func ( func(, string) (bool, error), []InternalTest, []InternalBenchmark, []InternalExample) { os.Exit(MainStart(matchStringOnly(), , , ).Run()) } // M is a type passed to a TestMain function to run the actual tests. type M struct { deps testDeps tests []InternalTest benchmarks []InternalBenchmark examples []InternalExample timer *time.Timer afterOnce sync.Once numRun int // value to pass to os.Exit, the outer test func main // harness calls os.Exit with this code. See #34129. exitCode int } // testDeps is an internal interface of functionality that is // passed into this package by a test's generated main package. // The canonical implementation of this interface is // testing/internal/testdeps's TestDeps. type testDeps interface { ImportPath() string MatchString(pat, str string) (bool, error) SetPanicOnExit0(bool) StartCPUProfile(io.Writer) error StopCPUProfile() StartTestLog(io.Writer) StopTestLog() error WriteProfileTo(string, io.Writer, int) error } // 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 ( testDeps, []InternalTest, []InternalBenchmark, []InternalExample) *M { Init() return &M{ deps: , tests: , benchmarks: , examples: , } } // Run runs the tests. It returns an exit code to pass to os.Exit. func ( *M) () ( int) { defer func() { = .exitCode }() // Count the number of calls to m.Run. // We only ever expected 1, but we didn't enforce that, // and now there are tests in the wild that call m.Run multiple times. // Sigh. golang.org/issue/23129. .numRun++ // TestMain may have already called flag.Parse. if !flag.Parsed() { flag.Parse() } if *parallel < 1 { fmt.Fprintln(os.Stderr, "testing: -parallel can only be given a positive integer") flag.Usage() .exitCode = 2 return } if len(*matchList) != 0 { listTests(.deps.MatchString, .tests, .benchmarks, .examples) .exitCode = 0 return } parseCpuList() .before() defer .after() := .startAlarm() haveExamples = len(.examples) > 0 , := runTests(.deps.MatchString, .tests, ) , := runExamples(.deps.MatchString, .examples) .stopAlarm() if ! && ! && *matchBenchmarks == "" { fmt.Fprintln(os.Stderr, "testing: warning: no tests to run") } if ! || ! || !runBenchmarks(.deps.ImportPath(), .deps.MatchString, .benchmarks) || race.Errors() > 0 { fmt.Println("FAIL") .exitCode = 1 return } fmt.Println("PASS") .exitCode = 0 return } func ( *T) () { if .parent == nil { return } := fmtDuration(.duration) := "--- %s: %s (%s)\n" if .Failed() { .flushToParent(.name, , "FAIL", .name, ) } else if .chatty != nil { if .Skipped() { .flushToParent(.name, , "SKIP", .name, ) } else { .flushToParent(.name, , "PASS", .name, ) } } } func listTests( func(, string) (bool, error), []InternalTest, []InternalBenchmark, []InternalExample) { if , := (*matchList, "non-empty"); != nil { fmt.Fprintf(os.Stderr, "testing: invalid regexp in -test.list (%q): %s\n", *matchList, ) os.Exit(1) } for , := range { if , := (*matchList, .Name); { fmt.Println(.Name) } } for , := range { if , := (*matchList, .Name); { fmt.Println(.Name) } } for , := range { if , := (*matchList, .Name); { fmt.Println(.Name) } } } // RunTests is an internal function but exported because it is cross-package; // it is part of the implementation of the "go test" command. func ( func(, string) (bool, error), []InternalTest) ( bool) { var time.Time if *timeout > 0 { = time.Now().Add(*timeout) } , := runTests(, , ) if ! && !haveExamples { fmt.Fprintln(os.Stderr, "testing: warning: no tests to run") } return } func runTests( func(, string) (bool, error), []InternalTest, time.Time) (, bool) { = true for , := range cpuList { runtime.GOMAXPROCS() for := uint(0); < *count; ++ { if shouldFailFast() { break } := newTestContext(*parallel, newMatcher(, *match, "-test.run")) .deadline = := &T{ common: common{ signal: make(chan bool), barrier: make(chan bool), w: os.Stdout, }, context: , } if Verbose() { .chatty = newChattyPrinter(.w) } tRunner(, func( *T) { for , := range { .Run(.Name, .F) } // Run catching the signal rather than the tRunner as a separate // goroutine to avoid adding a goroutine during the sequential // phase as this pollutes the stacktrace output when aborting. go func() { <-.signal }() }) = && !.Failed() = || .ran } } return , } // before runs before all testing. func ( *M) () { if *memProfileRate > 0 { runtime.MemProfileRate = *memProfileRate } if *cpuProfile != "" { , := os.Create(toOutputDir(*cpuProfile)) if != nil { fmt.Fprintf(os.Stderr, "testing: %s\n", ) return } if := .deps.StartCPUProfile(); != nil { fmt.Fprintf(os.Stderr, "testing: can't start cpu profile: %s\n", ) .Close() return } // Could save f so after can call f.Close; not worth the effort. } if *traceFile != "" { , := os.Create(toOutputDir(*traceFile)) if != nil { fmt.Fprintf(os.Stderr, "testing: %s\n", ) return } if := trace.Start(); != nil { fmt.Fprintf(os.Stderr, "testing: can't start tracing: %s\n", ) .Close() return } // Could save f so after can call f.Close; not worth the effort. } if *blockProfile != "" && *blockProfileRate >= 0 { runtime.SetBlockProfileRate(*blockProfileRate) } if *mutexProfile != "" && *mutexProfileFraction >= 0 { runtime.SetMutexProfileFraction(*mutexProfileFraction) } 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) } if *testlog != "" { // Note: Not using toOutputDir. // This file is for use by cmd/go, not users. var *os.File var error if .numRun == 1 { , = os.Create(*testlog) } else { , = os.OpenFile(*testlog, os.O_WRONLY, 0) if == nil { .Seek(0, io.SeekEnd) } } if != nil { fmt.Fprintf(os.Stderr, "testing: %s\n", ) os.Exit(2) } .deps.StartTestLog() testlogFile = } if *panicOnExit0 { .deps.SetPanicOnExit0(true) } } // after runs after all testing. func ( *M) () { .afterOnce.Do(func() { .writeProfiles() }) // Restore PanicOnExit0 after every run, because we set it to true before // every run. Otherwise, if m.Run is called multiple times the behavior of // os.Exit(0) will not be restored after the second run. if *panicOnExit0 { .deps.SetPanicOnExit0(false) } } func ( *M) () { if *testlog != "" { if := .deps.StopTestLog(); != nil { fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, ) os.Exit(2) } if := testlogFile.Close(); != nil { fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, ) os.Exit(2) } } if *cpuProfile != "" { .deps.StopCPUProfile() // flushes profile to disk } if *traceFile != "" { trace.Stop() // flushes trace to disk } if *memProfile != "" { , := os.Create(toOutputDir(*memProfile)) if != nil { fmt.Fprintf(os.Stderr, "testing: %s\n", ) os.Exit(2) } runtime.GC() // materialize all statistics if = .deps.WriteProfileTo("allocs", , 0); != nil { fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *memProfile, ) os.Exit(2) } .Close() } if *blockProfile != "" && *blockProfileRate >= 0 { , := os.Create(toOutputDir(*blockProfile)) if != nil { fmt.Fprintf(os.Stderr, "testing: %s\n", ) os.Exit(2) } if = .deps.WriteProfileTo("block", , 0); != nil { fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *blockProfile, ) os.Exit(2) } .Close() } if *mutexProfile != "" && *mutexProfileFraction >= 0 { , := os.Create(toOutputDir(*mutexProfile)) if != nil { fmt.Fprintf(os.Stderr, "testing: %s\n", ) os.Exit(2) } if = .deps.WriteProfileTo("mutex", , 0); != nil { fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *mutexProfile, ) os.Exit(2) } .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( string) string { if *outputDir == "" || == "" { return } // 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 runtime.GOOS == "windows" && len() >= 2 { , := [0], [1] if ('a' <= && <= 'z' || 'A' <= && <= 'Z') && == ':' { // If path starts with a drive letter we're stuck with it regardless. return } } if os.IsPathSeparator([0]) { return } return fmt.Sprintf("%s%c%s", *outputDir, os.PathSeparator, ) } // startAlarm starts an alarm if requested. func ( *M) () time.Time { if *timeout <= 0 { return time.Time{} } := time.Now().Add(*timeout) .timer = time.AfterFunc(*timeout, func() { .after() debug.SetTraceback("all") panic(fmt.Sprintf("test timed out after %v", *timeout)) }) return } // stopAlarm turns off the alarm. func ( *M) () { if *timeout > 0 { .timer.Stop() } } func parseCpuList() { for , := range strings.Split(*cpuListStr, ",") { = strings.TrimSpace() if == "" { continue } , := strconv.Atoi() if != nil || <= 0 { fmt.Fprintf(os.Stderr, "testing: invalid value %q for -test.cpu\n", ) os.Exit(1) } cpuList = append(cpuList, ) } if cpuList == nil { cpuList = append(cpuList, runtime.GOMAXPROCS(-1)) } } func shouldFailFast() bool { return *failFast && atomic.LoadUint32(&numFailed) > 0 }