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Source file src/testing/testing.go

Documentation: testing

     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.
     4  
     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.
    11  //
    12  // Within these functions, use the Error, Fail or related methods to signal failure.
    13  //
    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".
    19  //
    20  // A simple test function looks like this:
    21  //
    22  //     func TestAbs(t *testing.T) {
    23  //         got := Abs(-1)
    24  //         if got != 1 {
    25  //             t.Errorf("Abs(-1) = %d; want 1", got)
    26  //         }
    27  //     }
    28  //
    29  // Benchmarks
    30  //
    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.
    35  //
    36  // For a description of the testing flags, see
    37  // https://golang.org/cmd/go/#hdr-Testing_flags
    38  //
    39  // A sample benchmark function looks like this:
    40  //     func BenchmarkRandInt(b *testing.B) {
    41  //         for i := 0; i < b.N; i++ {
    42  //             rand.Int()
    43  //         }
    44  //     }
    45  //
    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.
    51  //
    52  // If a benchmark needs some expensive setup before running, the timer
    53  // may be reset:
    54  //
    55  //     func BenchmarkBigLen(b *testing.B) {
    56  //         big := NewBig()
    57  //         b.ResetTimer()
    58  //         for i := 0; i < b.N; i++ {
    59  //             big.Len()
    60  //         }
    61  //     }
    62  //
    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:
    66  //
    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
    71  //             for pb.Next() {
    72  //                 buf.Reset()
    73  //                 templ.Execute(&buf, "World")
    74  //             }
    75  //         })
    76  //     }
    77  //
    78  // Examples
    79  //
    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:
    84  //
    85  //     func ExampleHello() {
    86  //         fmt.Println("hello")
    87  //         // Output: hello
    88  //     }
    89  //
    90  //     func ExampleSalutations() {
    91  //         fmt.Println("hello, and")
    92  //         fmt.Println("goodbye")
    93  //         // Output:
    94  //         // hello, and
    95  //         // goodbye
    96  //     }
    97  //
    98  // The comment prefix "Unordered output:" is like "Output:", but matches any
    99  // line order:
   100  //
   101  //     func ExamplePerm() {
   102  //         for _, value := range Perm(5) {
   103  //             fmt.Println(value)
   104  //         }
   105  //         // Unordered output: 4
   106  //         // 2
   107  //         // 1
   108  //         // 3
   109  //         // 0
   110  //     }
   111  //
   112  // Example functions without output comments are compiled but not executed.
   113  //
   114  // The naming convention to declare examples for the package, a function F, a type T and
   115  // method M on type T are:
   116  //
   117  //     func Example() { ... }
   118  //     func ExampleF() { ... }
   119  //     func ExampleT() { ... }
   120  //     func ExampleT_M() { ... }
   121  //
   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.
   125  //
   126  //     func Example_suffix() { ... }
   127  //     func ExampleF_suffix() { ... }
   128  //     func ExampleT_suffix() { ... }
   129  //     func ExampleT_M_suffix() { ... }
   130  //
   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.
   134  //
   135  // Skipping
   136  //
   137  // Tests or benchmarks may be skipped at run time with a call to
   138  // the Skip method of *T or *B:
   139  //
   140  //     func TestTimeConsuming(t *testing.T) {
   141  //         if testing.Short() {
   142  //             t.Skip("skipping test in short mode.")
   143  //         }
   144  //         ...
   145  //     }
   146  //
   147  // Subtests and Sub-benchmarks
   148  //
   149  // The Run methods of T and B allow defining subtests and sub-benchmarks,
   150  // without having to define separate functions for each. This enables uses
   151  // like table-driven benchmarks and creating hierarchical tests.
   152  // It also provides a way to share common setup and tear-down code:
   153  //
   154  //     func TestFoo(t *testing.T) {
   155  //         // <setup code>
   156  //         t.Run("A=1", func(t *testing.T) { ... })
   157  //         t.Run("A=2", func(t *testing.T) { ... })
   158  //         t.Run("B=1", func(t *testing.T) { ... })
   159  //         // <tear-down code>
   160  //     }
   161  //
   162  // Each subtest and sub-benchmark has a unique name: the combination of the name
   163  // of the top-level test and the sequence of names passed to Run, separated by
   164  // slashes, with an optional trailing sequence number for disambiguation.
   165  //
   166  // The argument to the -run and -bench command-line flags is an unanchored regular
   167  // expression that matches the test's name. For tests with multiple slash-separated
   168  // elements, such as subtests, the argument is itself slash-separated, with
   169  // expressions matching each name element in turn. Because it is unanchored, an
   170  // empty expression matches any string.
   171  // For example, using "matching" to mean "whose name contains":
   172  //
   173  //     go test -run ''      # Run all tests.
   174  //     go test -run Foo     # Run top-level tests matching "Foo", such as "TestFooBar".
   175  //     go test -run Foo/A=  # For top-level tests matching "Foo", run subtests matching "A=".
   176  //     go test -run /A=1    # For all top-level tests, run subtests matching "A=1".
   177  //
   178  // Subtests can also be used to control parallelism. A parent test will only
   179  // complete once all of its subtests complete. In this example, all tests are
   180  // run in parallel with each other, and only with each other, regardless of
   181  // other top-level tests that may be defined:
   182  //
   183  //     func TestGroupedParallel(t *testing.T) {
   184  //         for _, tc := range tests {
   185  //             tc := tc // capture range variable
   186  //             t.Run(tc.Name, func(t *testing.T) {
   187  //                 t.Parallel()
   188  //                 ...
   189  //             })
   190  //         }
   191  //     }
   192  //
   193  // The race detector kills the program if it exceeds 8192 concurrent goroutines,
   194  // so use care when running parallel tests with the -race flag set.
   195  //
   196  // Run does not return until parallel subtests have completed, providing a way
   197  // to clean up after a group of parallel tests:
   198  //
   199  //     func TestTeardownParallel(t *testing.T) {
   200  //         // This Run will not return until the parallel tests finish.
   201  //         t.Run("group", func(t *testing.T) {
   202  //             t.Run("Test1", parallelTest1)
   203  //             t.Run("Test2", parallelTest2)
   204  //             t.Run("Test3", parallelTest3)
   205  //         })
   206  //         // <tear-down code>
   207  //     }
   208  //
   209  // Main
   210  //
   211  // It is sometimes necessary for a test program to do extra setup or teardown
   212  // before or after testing. It is also sometimes necessary for a test to control
   213  // which code runs on the main thread. To support these and other cases,
   214  // if a test file contains a function:
   215  //
   216  //	func TestMain(m *testing.M)
   217  //
   218  // then the generated test will call TestMain(m) instead of running the tests
   219  // directly. TestMain runs in the main goroutine and can do whatever setup
   220  // and teardown is necessary around a call to m.Run. m.Run will return an exit
   221  // code that may be passed to os.Exit. If TestMain returns, the test wrapper
   222  // will pass the result of m.Run to os.Exit itself.
   223  //
   224  // When TestMain is called, flag.Parse has not been run. If TestMain depends on
   225  // command-line flags, including those of the testing package, it should call
   226  // flag.Parse explicitly. Command line flags are always parsed by the time test
   227  // or benchmark functions run.
   228  //
   229  // A simple implementation of TestMain is:
   230  //
   231  //	func TestMain(m *testing.M) {
   232  //		// call flag.Parse() here if TestMain uses flags
   233  //		os.Exit(m.Run())
   234  //	}
   235  //
   236  package testing
   237  
   238  import (
   239  	"bytes"
   240  	"errors"
   241  	"flag"
   242  	"fmt"
   243  	"internal/race"
   244  	"io"
   245  	"os"
   246  	"runtime"
   247  	"runtime/debug"
   248  	"runtime/trace"
   249  	"strconv"
   250  	"strings"
   251  	"sync"
   252  	"sync/atomic"
   253  	"time"
   254  )
   255  
   256  var initRan bool
   257  
   258  // Init registers testing flags. These flags are automatically registered by
   259  // the "go test" command before running test functions, so Init is only needed
   260  // when calling functions such as Benchmark without using "go test".
   261  //
   262  // Init has no effect if it was already called.
   263  func Init() {
   264  	if initRan {
   265  		return
   266  	}
   267  	initRan = true
   268  	// The short flag requests that tests run more quickly, but its functionality
   269  	// is provided by test writers themselves. The testing package is just its
   270  	// home. The all.bash installation script sets it to make installation more
   271  	// efficient, but by default the flag is off so a plain "go test" will do a
   272  	// full test of the package.
   273  	short = flag.Bool("test.short", false, "run smaller test suite to save time")
   274  
   275  	// The failfast flag requests that test execution stop after the first test failure.
   276  	failFast = flag.Bool("test.failfast", false, "do not start new tests after the first test failure")
   277  
   278  	// The directory in which to create profile files and the like. When run from
   279  	// "go test", the binary always runs in the source directory for the package;
   280  	// this flag lets "go test" tell the binary to write the files in the directory where
   281  	// the "go test" command is run.
   282  	outputDir = flag.String("test.outputdir", "", "write profiles to `dir`")
   283  	// Report as tests are run; default is silent for success.
   284  	chatty = flag.Bool("test.v", false, "verbose: print additional output")
   285  	count = flag.Uint("test.count", 1, "run tests and benchmarks `n` times")
   286  	coverProfile = flag.String("test.coverprofile", "", "write a coverage profile to `file`")
   287  	matchList = flag.String("test.list", "", "list tests, examples, and benchmarks matching `regexp` then exit")
   288  	match = flag.String("test.run", "", "run only tests and examples matching `regexp`")
   289  	memProfile = flag.String("test.memprofile", "", "write an allocation profile to `file`")
   290  	memProfileRate = flag.Int("test.memprofilerate", 0, "set memory allocation profiling `rate` (see runtime.MemProfileRate)")
   291  	cpuProfile = flag.String("test.cpuprofile", "", "write a cpu profile to `file`")
   292  	blockProfile = flag.String("test.blockprofile", "", "write a goroutine blocking profile to `file`")
   293  	blockProfileRate = flag.Int("test.blockprofilerate", 1, "set blocking profile `rate` (see runtime.SetBlockProfileRate)")
   294  	mutexProfile = flag.String("test.mutexprofile", "", "write a mutex contention profile to the named file after execution")
   295  	mutexProfileFraction = flag.Int("test.mutexprofilefraction", 1, "if >= 0, calls runtime.SetMutexProfileFraction()")
   296  	panicOnExit0 = flag.Bool("test.paniconexit0", false, "panic on call to os.Exit(0)")
   297  	traceFile = flag.String("test.trace", "", "write an execution trace to `file`")
   298  	timeout = flag.Duration("test.timeout", 0, "panic test binary after duration `d` (default 0, timeout disabled)")
   299  	cpuListStr = flag.String("test.cpu", "", "comma-separated `list` of cpu counts to run each test with")
   300  	parallel = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "run at most `n` tests in parallel")
   301  	testlog = flag.String("test.testlogfile", "", "write test action log to `file` (for use only by cmd/go)")
   302  
   303  	initBenchmarkFlags()
   304  }
   305  
   306  var (
   307  	// Flags, registered during Init.
   308  	short                *bool
   309  	failFast             *bool
   310  	outputDir            *string
   311  	chatty               *bool
   312  	count                *uint
   313  	coverProfile         *string
   314  	matchList            *string
   315  	match                *string
   316  	memProfile           *string
   317  	memProfileRate       *int
   318  	cpuProfile           *string
   319  	blockProfile         *string
   320  	blockProfileRate     *int
   321  	mutexProfile         *string
   322  	mutexProfileFraction *int
   323  	panicOnExit0         *bool
   324  	traceFile            *string
   325  	timeout              *time.Duration
   326  	cpuListStr           *string
   327  	parallel             *int
   328  	testlog              *string
   329  
   330  	haveExamples bool // are there examples?
   331  
   332  	cpuList     []int
   333  	testlogFile *os.File
   334  
   335  	numFailed uint32 // number of test failures
   336  )
   337  
   338  type chattyPrinter struct {
   339  	w          io.Writer
   340  	lastNameMu sync.Mutex // guards lastName
   341  	lastName   string     // last printed test name in chatty mode
   342  }
   343  
   344  func newChattyPrinter(w io.Writer) *chattyPrinter {
   345  	return &chattyPrinter{w: w}
   346  }
   347  
   348  // Updatef prints a message about the status of the named test to w.
   349  //
   350  // The formatted message must include the test name itself.
   351  func (p *chattyPrinter) Updatef(testName, format string, args ...interface{}) {
   352  	p.lastNameMu.Lock()
   353  	defer p.lastNameMu.Unlock()
   354  
   355  	// Since the message already implies an association with a specific new test,
   356  	// we don't need to check what the old test name was or log an extra CONT line
   357  	// for it. (We're updating it anyway, and the current message already includes
   358  	// the test name.)
   359  	p.lastName = testName
   360  	fmt.Fprintf(p.w, format, args...)
   361  }
   362  
   363  // Printf prints a message, generated by the named test, that does not
   364  // necessarily mention that tests's name itself.
   365  func (p *chattyPrinter) Printf(testName, format string, args ...interface{}) {
   366  	p.lastNameMu.Lock()
   367  	defer p.lastNameMu.Unlock()
   368  
   369  	if p.lastName == "" {
   370  		p.lastName = testName
   371  	} else if p.lastName != testName {
   372  		fmt.Fprintf(p.w, "=== CONT  %s\n", testName)
   373  		p.lastName = testName
   374  	}
   375  
   376  	fmt.Fprintf(p.w, format, args...)
   377  }
   378  
   379  // The maximum number of stack frames to go through when skipping helper functions for
   380  // the purpose of decorating log messages.
   381  const maxStackLen = 50
   382  
   383  // common holds the elements common between T and B and
   384  // captures common methods such as Errorf.
   385  type common struct {
   386  	mu          sync.RWMutex         // guards this group of fields
   387  	output      []byte               // Output generated by test or benchmark.
   388  	w           io.Writer            // For flushToParent.
   389  	ran         bool                 // Test or benchmark (or one of its subtests) was executed.
   390  	failed      bool                 // Test or benchmark has failed.
   391  	skipped     bool                 // Test of benchmark has been skipped.
   392  	done        bool                 // Test is finished and all subtests have completed.
   393  	helperPCs   map[uintptr]struct{} // functions to be skipped when writing file/line info
   394  	helperNames map[string]struct{}  // helperPCs converted to function names
   395  	cleanups    []func()             // optional functions to be called at the end of the test
   396  	cleanupName string               // Name of the cleanup function.
   397  	cleanupPc   []uintptr            // The stack trace at the point where Cleanup was called.
   398  
   399  	chatty     *chattyPrinter // A copy of chattyPrinter, if the chatty flag is set.
   400  	bench      bool           // Whether the current test is a benchmark.
   401  	finished   bool           // Test function has completed.
   402  	hasSub     int32          // Written atomically.
   403  	raceErrors int            // Number of races detected during test.
   404  	runner     string         // Function name of tRunner running the test.
   405  
   406  	parent   *common
   407  	level    int       // Nesting depth of test or benchmark.
   408  	creator  []uintptr // If level > 0, the stack trace at the point where the parent called t.Run.
   409  	name     string    // Name of test or benchmark.
   410  	start    time.Time // Time test or benchmark started
   411  	duration time.Duration
   412  	barrier  chan bool // To signal parallel subtests they may start.
   413  	signal   chan bool // To signal a test is done.
   414  	sub      []*T      // Queue of subtests to be run in parallel.
   415  
   416  	tempDirMu  sync.Mutex
   417  	tempDir    string
   418  	tempDirErr error
   419  	tempDirSeq int32
   420  }
   421  
   422  // Short reports whether the -test.short flag is set.
   423  func Short() bool {
   424  	if short == nil {
   425  		panic("testing: Short called before Init")
   426  	}
   427  	// Catch code that calls this from TestMain without first calling flag.Parse.
   428  	if !flag.Parsed() {
   429  		panic("testing: Short called before Parse")
   430  	}
   431  
   432  	return *short
   433  }
   434  
   435  // CoverMode reports what the test coverage mode is set to. The
   436  // values are "set", "count", or "atomic". The return value will be
   437  // empty if test coverage is not enabled.
   438  func CoverMode() string {
   439  	return cover.Mode
   440  }
   441  
   442  // Verbose reports whether the -test.v flag is set.
   443  func Verbose() bool {
   444  	// Same as in Short.
   445  	if chatty == nil {
   446  		panic("testing: Verbose called before Init")
   447  	}
   448  	if !flag.Parsed() {
   449  		panic("testing: Verbose called before Parse")
   450  	}
   451  	return *chatty
   452  }
   453  
   454  // frameSkip searches, starting after skip frames, for the first caller frame
   455  // in a function not marked as a helper and returns that frame.
   456  // The search stops if it finds a tRunner function that
   457  // was the entry point into the test and the test is not a subtest.
   458  // This function must be called with c.mu held.
   459  func (c *common) frameSkip(skip int) runtime.Frame {
   460  	// If the search continues into the parent test, we'll have to hold
   461  	// its mu temporarily. If we then return, we need to unlock it.
   462  	shouldUnlock := false
   463  	defer func() {
   464  		if shouldUnlock {
   465  			c.mu.Unlock()
   466  		}
   467  	}()
   468  	var pc [maxStackLen]uintptr
   469  	// Skip two extra frames to account for this function
   470  	// and runtime.Callers itself.
   471  	n := runtime.Callers(skip+2, pc[:])
   472  	if n == 0 {
   473  		panic("testing: zero callers found")
   474  	}
   475  	frames := runtime.CallersFrames(pc[:n])
   476  	var firstFrame, prevFrame, frame runtime.Frame
   477  	for more := true; more; prevFrame = frame {
   478  		frame, more = frames.Next()
   479  		if frame.Function == c.cleanupName {
   480  			frames = runtime.CallersFrames(c.cleanupPc)
   481  			continue
   482  		}
   483  		if firstFrame.PC == 0 {
   484  			firstFrame = frame
   485  		}
   486  		if frame.Function == c.runner {
   487  			// We've gone up all the way to the tRunner calling
   488  			// the test function (so the user must have
   489  			// called tb.Helper from inside that test function).
   490  			// If this is a top-level test, only skip up to the test function itself.
   491  			// If we're in a subtest, continue searching in the parent test,
   492  			// starting from the point of the call to Run which created this subtest.
   493  			if c.level > 1 {
   494  				frames = runtime.CallersFrames(c.creator)
   495  				parent := c.parent
   496  				// We're no longer looking at the current c after this point,
   497  				// so we should unlock its mu, unless it's the original receiver,
   498  				// in which case our caller doesn't expect us to do that.
   499  				if shouldUnlock {
   500  					c.mu.Unlock()
   501  				}
   502  				c = parent
   503  				// Remember to unlock c.mu when we no longer need it, either
   504  				// because we went up another nesting level, or because we
   505  				// returned.
   506  				shouldUnlock = true
   507  				c.mu.Lock()
   508  				continue
   509  			}
   510  			return prevFrame
   511  		}
   512  		if _, ok := c.helperNames[frame.Function]; !ok {
   513  			// Found a frame that wasn't inside a helper function.
   514  			return frame
   515  		}
   516  	}
   517  	return firstFrame
   518  }
   519  
   520  // decorate prefixes the string with the file and line of the call site
   521  // and inserts the final newline if needed and indentation spaces for formatting.
   522  // This function must be called with c.mu held.
   523  func (c *common) decorate(s string, skip int) string {
   524  	// If more helper PCs have been added since we last did the conversion
   525  	if c.helperNames == nil {
   526  		c.helperNames = make(map[string]struct{})
   527  		for pc := range c.helperPCs {
   528  			c.helperNames[pcToName(pc)] = struct{}{}
   529  		}
   530  	}
   531  
   532  	frame := c.frameSkip(skip)
   533  	file := frame.File
   534  	line := frame.Line
   535  	if file != "" {
   536  		// Truncate file name at last file name separator.
   537  		if index := strings.LastIndex(file, "/"); index >= 0 {
   538  			file = file[index+1:]
   539  		} else if index = strings.LastIndex(file, "\\"); index >= 0 {
   540  			file = file[index+1:]
   541  		}
   542  	} else {
   543  		file = "???"
   544  	}
   545  	if line == 0 {
   546  		line = 1
   547  	}
   548  	buf := new(strings.Builder)
   549  	// Every line is indented at least 4 spaces.
   550  	buf.WriteString("    ")
   551  	fmt.Fprintf(buf, "%s:%d: ", file, line)
   552  	lines := strings.Split(s, "\n")
   553  	if l := len(lines); l > 1 && lines[l-1] == "" {
   554  		lines = lines[:l-1]
   555  	}
   556  	for i, line := range lines {
   557  		if i > 0 {
   558  			// Second and subsequent lines are indented an additional 4 spaces.
   559  			buf.WriteString("\n        ")
   560  		}
   561  		buf.WriteString(line)
   562  	}
   563  	buf.WriteByte('\n')
   564  	return buf.String()
   565  }
   566  
   567  // flushToParent writes c.output to the parent after first writing the header
   568  // with the given format and arguments.
   569  func (c *common) flushToParent(testName, format string, args ...interface{}) {
   570  	p := c.parent
   571  	p.mu.Lock()
   572  	defer p.mu.Unlock()
   573  
   574  	c.mu.Lock()
   575  	defer c.mu.Unlock()
   576  
   577  	if len(c.output) > 0 {
   578  		format += "%s"
   579  		args = append(args[:len(args):len(args)], c.output)
   580  		c.output = c.output[:0] // but why?
   581  	}
   582  
   583  	if c.chatty != nil && p.w == c.chatty.w {
   584  		// We're flushing to the actual output, so track that this output is
   585  		// associated with a specific test (and, specifically, that the next output
   586  		// is *not* associated with that test).
   587  		//
   588  		// Moreover, if c.output is non-empty it is important that this write be
   589  		// atomic with respect to the output of other tests, so that we don't end up
   590  		// with confusing '=== CONT' lines in the middle of our '--- PASS' block.
   591  		// Neither humans nor cmd/test2json can parse those easily.
   592  		// (See https://golang.org/issue/40771.)
   593  		c.chatty.Updatef(testName, format, args...)
   594  	} else {
   595  		// We're flushing to the output buffer of the parent test, which will
   596  		// itself follow a test-name header when it is finally flushed to stdout.
   597  		fmt.Fprintf(p.w, format, args...)
   598  	}
   599  }
   600  
   601  type indenter struct {
   602  	c *common
   603  }
   604  
   605  func (w indenter) Write(b []byte) (n int, err error) {
   606  	n = len(b)
   607  	for len(b) > 0 {
   608  		end := bytes.IndexByte(b, '\n')
   609  		if end == -1 {
   610  			end = len(b)
   611  		} else {
   612  			end++
   613  		}
   614  		// An indent of 4 spaces will neatly align the dashes with the status
   615  		// indicator of the parent.
   616  		const indent = "    "
   617  		w.c.output = append(w.c.output, indent...)
   618  		w.c.output = append(w.c.output, b[:end]...)
   619  		b = b[end:]
   620  	}
   621  	return
   622  }
   623  
   624  // fmtDuration returns a string representing d in the form "87.00s".
   625  func fmtDuration(d time.Duration) string {
   626  	return fmt.Sprintf("%.2fs", d.Seconds())
   627  }
   628  
   629  // TB is the interface common to T and B.
   630  type TB interface {
   631  	Cleanup(func())
   632  	Error(args ...interface{})
   633  	Errorf(format string, args ...interface{})
   634  	Fail()
   635  	FailNow()
   636  	Failed() bool
   637  	Fatal(args ...interface{})
   638  	Fatalf(format string, args ...interface{})
   639  	Helper()
   640  	Log(args ...interface{})
   641  	Logf(format string, args ...interface{})
   642  	Name() string
   643  	Skip(args ...interface{})
   644  	SkipNow()
   645  	Skipf(format string, args ...interface{})
   646  	Skipped() bool
   647  	TempDir() string
   648  
   649  	// A private method to prevent users implementing the
   650  	// interface and so future additions to it will not
   651  	// violate Go 1 compatibility.
   652  	private()
   653  }
   654  
   655  var _ TB = (*T)(nil)
   656  var _ TB = (*B)(nil)
   657  
   658  // T is a type passed to Test functions to manage test state and support formatted test logs.
   659  //
   660  // A test ends when its Test function returns or calls any of the methods
   661  // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods, as well as
   662  // the Parallel method, must be called only from the goroutine running the
   663  // Test function.
   664  //
   665  // The other reporting methods, such as the variations of Log and Error,
   666  // may be called simultaneously from multiple goroutines.
   667  type T struct {
   668  	common
   669  	isParallel bool
   670  	context    *testContext // For running tests and subtests.
   671  }
   672  
   673  func (c *common) private() {}
   674  
   675  // Name returns the name of the running test or benchmark.
   676  func (c *common) Name() string {
   677  	return c.name
   678  }
   679  
   680  func (c *common) setRan() {
   681  	if c.parent != nil {
   682  		c.parent.setRan()
   683  	}
   684  	c.mu.Lock()
   685  	defer c.mu.Unlock()
   686  	c.ran = true
   687  }
   688  
   689  // Fail marks the function as having failed but continues execution.
   690  func (c *common) Fail() {
   691  	if c.parent != nil {
   692  		c.parent.Fail()
   693  	}
   694  	c.mu.Lock()
   695  	defer c.mu.Unlock()
   696  	// c.done needs to be locked to synchronize checks to c.done in parent tests.
   697  	if c.done {
   698  		panic("Fail in goroutine after " + c.name + " has completed")
   699  	}
   700  	c.failed = true
   701  }
   702  
   703  // Failed reports whether the function has failed.
   704  func (c *common) Failed() bool {
   705  	c.mu.RLock()
   706  	failed := c.failed
   707  	c.mu.RUnlock()
   708  	return failed || c.raceErrors+race.Errors() > 0
   709  }
   710  
   711  // FailNow marks the function as having failed and stops its execution
   712  // by calling runtime.Goexit (which then runs all deferred calls in the
   713  // current goroutine).
   714  // Execution will continue at the next test or benchmark.
   715  // FailNow must be called from the goroutine running the
   716  // test or benchmark function, not from other goroutines
   717  // created during the test. Calling FailNow does not stop
   718  // those other goroutines.
   719  func (c *common) FailNow() {
   720  	c.Fail()
   721  
   722  	// Calling runtime.Goexit will exit the goroutine, which
   723  	// will run the deferred functions in this goroutine,
   724  	// which will eventually run the deferred lines in tRunner,
   725  	// which will signal to the test loop that this test is done.
   726  	//
   727  	// A previous version of this code said:
   728  	//
   729  	//	c.duration = ...
   730  	//	c.signal <- c.self
   731  	//	runtime.Goexit()
   732  	//
   733  	// This previous version duplicated code (those lines are in
   734  	// tRunner no matter what), but worse the goroutine teardown
   735  	// implicit in runtime.Goexit was not guaranteed to complete
   736  	// before the test exited. If a test deferred an important cleanup
   737  	// function (like removing temporary files), there was no guarantee
   738  	// it would run on a test failure. Because we send on c.signal during
   739  	// a top-of-stack deferred function now, we know that the send
   740  	// only happens after any other stacked defers have completed.
   741  	c.finished = true
   742  	runtime.Goexit()
   743  }
   744  
   745  // log generates the output. It's always at the same stack depth.
   746  func (c *common) log(s string) {
   747  	c.logDepth(s, 3) // logDepth + log + public function
   748  }
   749  
   750  // logDepth generates the output at an arbitrary stack depth.
   751  func (c *common) logDepth(s string, depth int) {
   752  	c.mu.Lock()
   753  	defer c.mu.Unlock()
   754  	if c.done {
   755  		// This test has already finished. Try and log this message
   756  		// with our parent. If we don't have a parent, panic.
   757  		for parent := c.parent; parent != nil; parent = parent.parent {
   758  			parent.mu.Lock()
   759  			defer parent.mu.Unlock()
   760  			if !parent.done {
   761  				parent.output = append(parent.output, parent.decorate(s, depth+1)...)
   762  				return
   763  			}
   764  		}
   765  		panic("Log in goroutine after " + c.name + " has completed")
   766  	} else {
   767  		if c.chatty != nil {
   768  			if c.bench {
   769  				// Benchmarks don't print === CONT, so we should skip the test
   770  				// printer and just print straight to stdout.
   771  				fmt.Print(c.decorate(s, depth+1))
   772  			} else {
   773  				c.chatty.Printf(c.name, "%s", c.decorate(s, depth+1))
   774  			}
   775  
   776  			return
   777  		}
   778  		c.output = append(c.output, c.decorate(s, depth+1)...)
   779  	}
   780  }
   781  
   782  // Log formats its arguments using default formatting, analogous to Println,
   783  // and records the text in the error log. For tests, the text will be printed only if
   784  // the test fails or the -test.v flag is set. For benchmarks, the text is always
   785  // printed to avoid having performance depend on the value of the -test.v flag.
   786  func (c *common) Log(args ...interface{}) { c.log(fmt.Sprintln(args...)) }
   787  
   788  // Logf formats its arguments according to the format, analogous to Printf, and
   789  // records the text in the error log. A final newline is added if not provided. For
   790  // tests, the text will be printed only if the test fails or the -test.v flag is
   791  // set. For benchmarks, the text is always printed to avoid having performance
   792  // depend on the value of the -test.v flag.
   793  func (c *common) Logf(format string, args ...interface{}) { c.log(fmt.Sprintf(format, args...)) }
   794  
   795  // Error is equivalent to Log followed by Fail.
   796  func (c *common) Error(args ...interface{}) {
   797  	c.log(fmt.Sprintln(args...))
   798  	c.Fail()
   799  }
   800  
   801  // Errorf is equivalent to Logf followed by Fail.
   802  func (c *common) Errorf(format string, args ...interface{}) {
   803  	c.log(fmt.Sprintf(format, args...))
   804  	c.Fail()
   805  }
   806  
   807  // Fatal is equivalent to Log followed by FailNow.
   808  func (c *common) Fatal(args ...interface{}) {
   809  	c.log(fmt.Sprintln(args...))
   810  	c.FailNow()
   811  }
   812  
   813  // Fatalf is equivalent to Logf followed by FailNow.
   814  func (c *common) Fatalf(format string, args ...interface{}) {
   815  	c.log(fmt.Sprintf(format, args...))
   816  	c.FailNow()
   817  }
   818  
   819  // Skip is equivalent to Log followed by SkipNow.
   820  func (c *common) Skip(args ...interface{}) {
   821  	c.log(fmt.Sprintln(args...))
   822  	c.SkipNow()
   823  }
   824  
   825  // Skipf is equivalent to Logf followed by SkipNow.
   826  func (c *common) Skipf(format string, args ...interface{}) {
   827  	c.log(fmt.Sprintf(format, args...))
   828  	c.SkipNow()
   829  }
   830  
   831  // SkipNow marks the test as having been skipped and stops its execution
   832  // by calling runtime.Goexit.
   833  // If a test fails (see Error, Errorf, Fail) and is then skipped,
   834  // it is still considered to have failed.
   835  // Execution will continue at the next test or benchmark. See also FailNow.
   836  // SkipNow must be called from the goroutine running the test, not from
   837  // other goroutines created during the test. Calling SkipNow does not stop
   838  // those other goroutines.
   839  func (c *common) SkipNow() {
   840  	c.skip()
   841  	c.finished = true
   842  	runtime.Goexit()
   843  }
   844  
   845  func (c *common) skip() {
   846  	c.mu.Lock()
   847  	defer c.mu.Unlock()
   848  	c.skipped = true
   849  }
   850  
   851  // Skipped reports whether the test was skipped.
   852  func (c *common) Skipped() bool {
   853  	c.mu.RLock()
   854  	defer c.mu.RUnlock()
   855  	return c.skipped
   856  }
   857  
   858  // Helper marks the calling function as a test helper function.
   859  // When printing file and line information, that function will be skipped.
   860  // Helper may be called simultaneously from multiple goroutines.
   861  func (c *common) Helper() {
   862  	c.mu.Lock()
   863  	defer c.mu.Unlock()
   864  	if c.helperPCs == nil {
   865  		c.helperPCs = make(map[uintptr]struct{})
   866  	}
   867  	// repeating code from callerName here to save walking a stack frame
   868  	var pc [1]uintptr
   869  	n := runtime.Callers(2, pc[:]) // skip runtime.Callers + Helper
   870  	if n == 0 {
   871  		panic("testing: zero callers found")
   872  	}
   873  	if _, found := c.helperPCs[pc[0]]; !found {
   874  		c.helperPCs[pc[0]] = struct{}{}
   875  		c.helperNames = nil // map will be recreated next time it is needed
   876  	}
   877  }
   878  
   879  // Cleanup registers a function to be called when the test and all its
   880  // subtests complete. Cleanup functions will be called in last added,
   881  // first called order.
   882  func (c *common) Cleanup(f func()) {
   883  	var pc [maxStackLen]uintptr
   884  	// Skip two extra frames to account for this function and runtime.Callers itself.
   885  	n := runtime.Callers(2, pc[:])
   886  	cleanupPc := pc[:n]
   887  
   888  	fn := func() {
   889  		defer func() {
   890  			c.mu.Lock()
   891  			defer c.mu.Unlock()
   892  			c.cleanupName = ""
   893  			c.cleanupPc = nil
   894  		}()
   895  
   896  		name := callerName(0)
   897  		c.mu.Lock()
   898  		c.cleanupName = name
   899  		c.cleanupPc = cleanupPc
   900  		c.mu.Unlock()
   901  
   902  		f()
   903  	}
   904  
   905  	c.mu.Lock()
   906  	defer c.mu.Unlock()
   907  	c.cleanups = append(c.cleanups, fn)
   908  }
   909  
   910  var tempDirReplacer struct {
   911  	sync.Once
   912  	r *strings.Replacer
   913  }
   914  
   915  // TempDir returns a temporary directory for the test to use.
   916  // The directory is automatically removed by Cleanup when the test and
   917  // all its subtests complete.
   918  // Each subsequent call to t.TempDir returns a unique directory;
   919  // if the directory creation fails, TempDir terminates the test by calling Fatal.
   920  func (c *common) TempDir() string {
   921  	// Use a single parent directory for all the temporary directories
   922  	// created by a test, each numbered sequentially.
   923  	c.tempDirMu.Lock()
   924  	var nonExistent bool
   925  	if c.tempDir == "" { // Usually the case with js/wasm
   926  		nonExistent = true
   927  	} else {
   928  		_, err := os.Stat(c.tempDir)
   929  		nonExistent = os.IsNotExist(err)
   930  		if err != nil && !nonExistent {
   931  			c.Fatalf("TempDir: %v", err)
   932  		}
   933  	}
   934  
   935  	if nonExistent {
   936  		c.Helper()
   937  
   938  		// os.MkdirTemp doesn't like path separators in its pattern,
   939  		// so mangle the name to accommodate subtests.
   940  		tempDirReplacer.Do(func() {
   941  			tempDirReplacer.r = strings.NewReplacer("/", "_", "\\", "_", ":", "_")
   942  		})
   943  		pattern := tempDirReplacer.r.Replace(c.Name())
   944  
   945  		c.tempDir, c.tempDirErr = os.MkdirTemp("", pattern)
   946  		if c.tempDirErr == nil {
   947  			c.Cleanup(func() {
   948  				if err := os.RemoveAll(c.tempDir); err != nil {
   949  					c.Errorf("TempDir RemoveAll cleanup: %v", err)
   950  				}
   951  			})
   952  		}
   953  	}
   954  	c.tempDirMu.Unlock()
   955  
   956  	if c.tempDirErr != nil {
   957  		c.Fatalf("TempDir: %v", c.tempDirErr)
   958  	}
   959  	seq := atomic.AddInt32(&c.tempDirSeq, 1)
   960  	dir := fmt.Sprintf("%s%c%03d", c.tempDir, os.PathSeparator, seq)
   961  	if err := os.Mkdir(dir, 0777); err != nil {
   962  		c.Fatalf("TempDir: %v", err)
   963  	}
   964  	return dir
   965  }
   966  
   967  // panicHanding is an argument to runCleanup.
   968  type panicHandling int
   969  
   970  const (
   971  	normalPanic panicHandling = iota
   972  	recoverAndReturnPanic
   973  )
   974  
   975  // runCleanup is called at the end of the test.
   976  // If catchPanic is true, this will catch panics, and return the recovered
   977  // value if any.
   978  func (c *common) runCleanup(ph panicHandling) (panicVal interface{}) {
   979  	if ph == recoverAndReturnPanic {
   980  		defer func() {
   981  			panicVal = recover()
   982  		}()
   983  	}
   984  
   985  	// Make sure that if a cleanup function panics,
   986  	// we still run the remaining cleanup functions.
   987  	defer func() {
   988  		c.mu.Lock()
   989  		recur := len(c.cleanups) > 0
   990  		c.mu.Unlock()
   991  		if recur {
   992  			c.runCleanup(normalPanic)
   993  		}
   994  	}()
   995  
   996  	for {
   997  		var cleanup func()
   998  		c.mu.Lock()
   999  		if len(c.cleanups) > 0 {
  1000  			last := len(c.cleanups) - 1
  1001  			cleanup = c.cleanups[last]
  1002  			c.cleanups = c.cleanups[:last]
  1003  		}
  1004  		c.mu.Unlock()
  1005  		if cleanup == nil {
  1006  			return nil
  1007  		}
  1008  		cleanup()
  1009  	}
  1010  }
  1011  
  1012  // callerName gives the function name (qualified with a package path)
  1013  // for the caller after skip frames (where 0 means the current function).
  1014  func callerName(skip int) string {
  1015  	var pc [1]uintptr
  1016  	n := runtime.Callers(skip+2, pc[:]) // skip + runtime.Callers + callerName
  1017  	if n == 0 {
  1018  		panic("testing: zero callers found")
  1019  	}
  1020  	return pcToName(pc[0])
  1021  }
  1022  
  1023  func pcToName(pc uintptr) string {
  1024  	pcs := []uintptr{pc}
  1025  	frames := runtime.CallersFrames(pcs)
  1026  	frame, _ := frames.Next()
  1027  	return frame.Function
  1028  }
  1029  
  1030  // Parallel signals that this test is to be run in parallel with (and only with)
  1031  // other parallel tests. When a test is run multiple times due to use of
  1032  // -test.count or -test.cpu, multiple instances of a single test never run in
  1033  // parallel with each other.
  1034  func (t *T) Parallel() {
  1035  	if t.isParallel {
  1036  		panic("testing: t.Parallel called multiple times")
  1037  	}
  1038  	t.isParallel = true
  1039  
  1040  	// We don't want to include the time we spend waiting for serial tests
  1041  	// in the test duration. Record the elapsed time thus far and reset the
  1042  	// timer afterwards.
  1043  	t.duration += time.Since(t.start)
  1044  
  1045  	// Add to the list of tests to be released by the parent.
  1046  	t.parent.sub = append(t.parent.sub, t)
  1047  	t.raceErrors += race.Errors()
  1048  
  1049  	if t.chatty != nil {
  1050  		// Unfortunately, even though PAUSE indicates that the named test is *no
  1051  		// longer* running, cmd/test2json interprets it as changing the active test
  1052  		// for the purpose of log parsing. We could fix cmd/test2json, but that
  1053  		// won't fix existing deployments of third-party tools that already shell
  1054  		// out to older builds of cmd/test2json — so merely fixing cmd/test2json
  1055  		// isn't enough for now.
  1056  		t.chatty.Updatef(t.name, "=== PAUSE %s\n", t.name)
  1057  	}
  1058  
  1059  	t.signal <- true   // Release calling test.
  1060  	<-t.parent.barrier // Wait for the parent test to complete.
  1061  	t.context.waitParallel()
  1062  
  1063  	if t.chatty != nil {
  1064  		t.chatty.Updatef(t.name, "=== CONT  %s\n", t.name)
  1065  	}
  1066  
  1067  	t.start = time.Now()
  1068  	t.raceErrors += -race.Errors()
  1069  }
  1070  
  1071  // InternalTest is an internal type but exported because it is cross-package;
  1072  // it is part of the implementation of the "go test" command.
  1073  type InternalTest struct {
  1074  	Name string
  1075  	F    func(*T)
  1076  }
  1077  
  1078  var errNilPanicOrGoexit = errors.New("test executed panic(nil) or runtime.Goexit")
  1079  
  1080  func tRunner(t *T, fn func(t *T)) {
  1081  	t.runner = callerName(0)
  1082  
  1083  	// When this goroutine is done, either because fn(t)
  1084  	// returned normally or because a test failure triggered
  1085  	// a call to runtime.Goexit, record the duration and send
  1086  	// a signal saying that the test is done.
  1087  	defer func() {
  1088  		if t.Failed() {
  1089  			atomic.AddUint32(&numFailed, 1)
  1090  		}
  1091  
  1092  		if t.raceErrors+race.Errors() > 0 {
  1093  			t.Errorf("race detected during execution of test")
  1094  		}
  1095  
  1096  		// If the test panicked, print any test output before dying.
  1097  		err := recover()
  1098  		signal := true
  1099  
  1100  		if !t.finished && err == nil {
  1101  			err = errNilPanicOrGoexit
  1102  			for p := t.parent; p != nil; p = p.parent {
  1103  				if p.finished {
  1104  					t.Errorf("%v: subtest may have called FailNow on a parent test", err)
  1105  					err = nil
  1106  					signal = false
  1107  					break
  1108  				}
  1109  			}
  1110  		}
  1111  		// Use a deferred call to ensure that we report that the test is
  1112  		// complete even if a cleanup function calls t.FailNow. See issue 41355.
  1113  		didPanic := false
  1114  		defer func() {
  1115  			if didPanic {
  1116  				return
  1117  			}
  1118  			if err != nil {
  1119  				panic(err)
  1120  			}
  1121  			// Only report that the test is complete if it doesn't panic,
  1122  			// as otherwise the test binary can exit before the panic is
  1123  			// reported to the user. See issue 41479.
  1124  			t.signal <- signal
  1125  		}()
  1126  
  1127  		doPanic := func(err interface{}) {
  1128  			t.Fail()
  1129  			if r := t.runCleanup(recoverAndReturnPanic); r != nil {
  1130  				t.Logf("cleanup panicked with %v", r)
  1131  			}
  1132  			// Flush the output log up to the root before dying.
  1133  			for root := &t.common; root.parent != nil; root = root.parent {
  1134  				root.mu.Lock()
  1135  				root.duration += time.Since(root.start)
  1136  				d := root.duration
  1137  				root.mu.Unlock()
  1138  				root.flushToParent(root.name, "--- FAIL: %s (%s)\n", root.name, fmtDuration(d))
  1139  				if r := root.parent.runCleanup(recoverAndReturnPanic); r != nil {
  1140  					fmt.Fprintf(root.parent.w, "cleanup panicked with %v", r)
  1141  				}
  1142  			}
  1143  			didPanic = true
  1144  			panic(err)
  1145  		}
  1146  		if err != nil {
  1147  			doPanic(err)
  1148  		}
  1149  
  1150  		t.duration += time.Since(t.start)
  1151  
  1152  		if len(t.sub) > 0 {
  1153  			// Run parallel subtests.
  1154  			// Decrease the running count for this test.
  1155  			t.context.release()
  1156  			// Release the parallel subtests.
  1157  			close(t.barrier)
  1158  			// Wait for subtests to complete.
  1159  			for _, sub := range t.sub {
  1160  				<-sub.signal
  1161  			}
  1162  			cleanupStart := time.Now()
  1163  			err := t.runCleanup(recoverAndReturnPanic)
  1164  			t.duration += time.Since(cleanupStart)
  1165  			if err != nil {
  1166  				doPanic(err)
  1167  			}
  1168  			if !t.isParallel {
  1169  				// Reacquire the count for sequential tests. See comment in Run.
  1170  				t.context.waitParallel()
  1171  			}
  1172  		} else if t.isParallel {
  1173  			// Only release the count for this test if it was run as a parallel
  1174  			// test. See comment in Run method.
  1175  			t.context.release()
  1176  		}
  1177  		t.report() // Report after all subtests have finished.
  1178  
  1179  		// Do not lock t.done to allow race detector to detect race in case
  1180  		// the user does not appropriately synchronizes a goroutine.
  1181  		t.done = true
  1182  		if t.parent != nil && atomic.LoadInt32(&t.hasSub) == 0 {
  1183  			t.setRan()
  1184  		}
  1185  	}()
  1186  	defer func() {
  1187  		if len(t.sub) == 0 {
  1188  			t.runCleanup(normalPanic)
  1189  		}
  1190  	}()
  1191  
  1192  	t.start = time.Now()
  1193  	t.raceErrors = -race.Errors()
  1194  	fn(t)
  1195  
  1196  	// code beyond here will not be executed when FailNow is invoked
  1197  	t.finished = true
  1198  }
  1199  
  1200  // Run runs f as a subtest of t called name. It runs f in a separate goroutine
  1201  // and blocks until f returns or calls t.Parallel to become a parallel test.
  1202  // Run reports whether f succeeded (or at least did not fail before calling t.Parallel).
  1203  //
  1204  // Run may be called simultaneously from multiple goroutines, but all such calls
  1205  // must return before the outer test function for t returns.
  1206  func (t *T) Run(name string, f func(t *T)) bool {
  1207  	atomic.StoreInt32(&t.hasSub, 1)
  1208  	testName, ok, _ := t.context.match.fullName(&t.common, name)
  1209  	if !ok || shouldFailFast() {
  1210  		return true
  1211  	}
  1212  	// Record the stack trace at the point of this call so that if the subtest
  1213  	// function - which runs in a separate stack - is marked as a helper, we can
  1214  	// continue walking the stack into the parent test.
  1215  	var pc [maxStackLen]uintptr
  1216  	n := runtime.Callers(2, pc[:])
  1217  	t = &T{
  1218  		common: common{
  1219  			barrier: make(chan bool),
  1220  			signal:  make(chan bool),
  1221  			name:    testName,
  1222  			parent:  &t.common,
  1223  			level:   t.level + 1,
  1224  			creator: pc[:n],
  1225  			chatty:  t.chatty,
  1226  		},
  1227  		context: t.context,
  1228  	}
  1229  	t.w = indenter{&t.common}
  1230  
  1231  	if t.chatty != nil {
  1232  		t.chatty.Updatef(t.name, "=== RUN   %s\n", t.name)
  1233  	}
  1234  	// Instead of reducing the running count of this test before calling the
  1235  	// tRunner and increasing it afterwards, we rely on tRunner keeping the
  1236  	// count correct. This ensures that a sequence of sequential tests runs
  1237  	// without being preempted, even when their parent is a parallel test. This
  1238  	// may especially reduce surprises if *parallel == 1.
  1239  	go tRunner(t, f)
  1240  	if !<-t.signal {
  1241  		// At this point, it is likely that FailNow was called on one of the
  1242  		// parent tests by one of the subtests. Continue aborting up the chain.
  1243  		runtime.Goexit()
  1244  	}
  1245  	return !t.failed
  1246  }
  1247  
  1248  // Deadline reports the time at which the test binary will have
  1249  // exceeded the timeout specified by the -timeout flag.
  1250  //
  1251  // The ok result is false if the -timeout flag indicates “no timeout” (0).
  1252  func (t *T) Deadline() (deadline time.Time, ok bool) {
  1253  	deadline = t.context.deadline
  1254  	return deadline, !deadline.IsZero()
  1255  }
  1256  
  1257  // testContext holds all fields that are common to all tests. This includes
  1258  // synchronization primitives to run at most *parallel tests.
  1259  type testContext struct {
  1260  	match    *matcher
  1261  	deadline time.Time
  1262  
  1263  	mu sync.Mutex
  1264  
  1265  	// Channel used to signal tests that are ready to be run in parallel.
  1266  	startParallel chan bool
  1267  
  1268  	// running is the number of tests currently running in parallel.
  1269  	// This does not include tests that are waiting for subtests to complete.
  1270  	running int
  1271  
  1272  	// numWaiting is the number tests waiting to be run in parallel.
  1273  	numWaiting int
  1274  
  1275  	// maxParallel is a copy of the parallel flag.
  1276  	maxParallel int
  1277  }
  1278  
  1279  func newTestContext(maxParallel int, m *matcher) *testContext {
  1280  	return &testContext{
  1281  		match:         m,
  1282  		startParallel: make(chan bool),
  1283  		maxParallel:   maxParallel,
  1284  		running:       1, // Set the count to 1 for the main (sequential) test.
  1285  	}
  1286  }
  1287  
  1288  func (c *testContext) waitParallel() {
  1289  	c.mu.Lock()
  1290  	if c.running < c.maxParallel {
  1291  		c.running++
  1292  		c.mu.Unlock()
  1293  		return
  1294  	}
  1295  	c.numWaiting++
  1296  	c.mu.Unlock()
  1297  	<-c.startParallel
  1298  }
  1299  
  1300  func (c *testContext) release() {
  1301  	c.mu.Lock()
  1302  	if c.numWaiting == 0 {
  1303  		c.running--
  1304  		c.mu.Unlock()
  1305  		return
  1306  	}
  1307  	c.numWaiting--
  1308  	c.mu.Unlock()
  1309  	c.startParallel <- true // Pick a waiting test to be run.
  1310  }
  1311  
  1312  // No one should be using func Main anymore.
  1313  // See the doc comment on func Main and use MainStart instead.
  1314  var errMain = errors.New("testing: unexpected use of func Main")
  1315  
  1316  type matchStringOnly func(pat, str string) (bool, error)
  1317  
  1318  func (f matchStringOnly) MatchString(pat, str string) (bool, error)   { return f(pat, str) }
  1319  func (f matchStringOnly) StartCPUProfile(w io.Writer) error           { return errMain }
  1320  func (f matchStringOnly) StopCPUProfile()                             {}
  1321  func (f matchStringOnly) WriteProfileTo(string, io.Writer, int) error { return errMain }
  1322  func (f matchStringOnly) ImportPath() string                          { return "" }
  1323  func (f matchStringOnly) StartTestLog(io.Writer)                      {}
  1324  func (f matchStringOnly) StopTestLog() error                          { return errMain }
  1325  func (f matchStringOnly) SetPanicOnExit0(bool)                        {}
  1326  
  1327  // Main is an internal function, part of the implementation of the "go test" command.
  1328  // It was exported because it is cross-package and predates "internal" packages.
  1329  // It is no longer used by "go test" but preserved, as much as possible, for other
  1330  // systems that simulate "go test" using Main, but Main sometimes cannot be updated as
  1331  // new functionality is added to the testing package.
  1332  // Systems simulating "go test" should be updated to use MainStart.
  1333  func Main(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
  1334  	os.Exit(MainStart(matchStringOnly(matchString), tests, benchmarks, examples).Run())
  1335  }
  1336  
  1337  // M is a type passed to a TestMain function to run the actual tests.
  1338  type M struct {
  1339  	deps       testDeps
  1340  	tests      []InternalTest
  1341  	benchmarks []InternalBenchmark
  1342  	examples   []InternalExample
  1343  
  1344  	timer     *time.Timer
  1345  	afterOnce sync.Once
  1346  
  1347  	numRun int
  1348  
  1349  	// value to pass to os.Exit, the outer test func main
  1350  	// harness calls os.Exit with this code. See #34129.
  1351  	exitCode int
  1352  }
  1353  
  1354  // testDeps is an internal interface of functionality that is
  1355  // passed into this package by a test's generated main package.
  1356  // The canonical implementation of this interface is
  1357  // testing/internal/testdeps's TestDeps.
  1358  type testDeps interface {
  1359  	ImportPath() string
  1360  	MatchString(pat, str string) (bool, error)
  1361  	SetPanicOnExit0(bool)
  1362  	StartCPUProfile(io.Writer) error
  1363  	StopCPUProfile()
  1364  	StartTestLog(io.Writer)
  1365  	StopTestLog() error
  1366  	WriteProfileTo(string, io.Writer, int) error
  1367  }
  1368  
  1369  // MainStart is meant for use by tests generated by 'go test'.
  1370  // It is not meant to be called directly and is not subject to the Go 1 compatibility document.
  1371  // It may change signature from release to release.
  1372  func MainStart(deps testDeps, tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) *M {
  1373  	Init()
  1374  	return &M{
  1375  		deps:       deps,
  1376  		tests:      tests,
  1377  		benchmarks: benchmarks,
  1378  		examples:   examples,
  1379  	}
  1380  }
  1381  
  1382  // Run runs the tests. It returns an exit code to pass to os.Exit.
  1383  func (m *M) Run() (code int) {
  1384  	defer func() {
  1385  		code = m.exitCode
  1386  	}()
  1387  
  1388  	// Count the number of calls to m.Run.
  1389  	// We only ever expected 1, but we didn't enforce that,
  1390  	// and now there are tests in the wild that call m.Run multiple times.
  1391  	// Sigh. golang.org/issue/23129.
  1392  	m.numRun++
  1393  
  1394  	// TestMain may have already called flag.Parse.
  1395  	if !flag.Parsed() {
  1396  		flag.Parse()
  1397  	}
  1398  
  1399  	if *parallel < 1 {
  1400  		fmt.Fprintln(os.Stderr, "testing: -parallel can only be given a positive integer")
  1401  		flag.Usage()
  1402  		m.exitCode = 2
  1403  		return
  1404  	}
  1405  
  1406  	if len(*matchList) != 0 {
  1407  		listTests(m.deps.MatchString, m.tests, m.benchmarks, m.examples)
  1408  		m.exitCode = 0
  1409  		return
  1410  	}
  1411  
  1412  	parseCpuList()
  1413  
  1414  	m.before()
  1415  	defer m.after()
  1416  	deadline := m.startAlarm()
  1417  	haveExamples = len(m.examples) > 0
  1418  	testRan, testOk := runTests(m.deps.MatchString, m.tests, deadline)
  1419  	exampleRan, exampleOk := runExamples(m.deps.MatchString, m.examples)
  1420  	m.stopAlarm()
  1421  	if !testRan && !exampleRan && *matchBenchmarks == "" {
  1422  		fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
  1423  	}
  1424  	if !testOk || !exampleOk || !runBenchmarks(m.deps.ImportPath(), m.deps.MatchString, m.benchmarks) || race.Errors() > 0 {
  1425  		fmt.Println("FAIL")
  1426  		m.exitCode = 1
  1427  		return
  1428  	}
  1429  
  1430  	fmt.Println("PASS")
  1431  	m.exitCode = 0
  1432  	return
  1433  }
  1434  
  1435  func (t *T) report() {
  1436  	if t.parent == nil {
  1437  		return
  1438  	}
  1439  	dstr := fmtDuration(t.duration)
  1440  	format := "--- %s: %s (%s)\n"
  1441  	if t.Failed() {
  1442  		t.flushToParent(t.name, format, "FAIL", t.name, dstr)
  1443  	} else if t.chatty != nil {
  1444  		if t.Skipped() {
  1445  			t.flushToParent(t.name, format, "SKIP", t.name, dstr)
  1446  		} else {
  1447  			t.flushToParent(t.name, format, "PASS", t.name, dstr)
  1448  		}
  1449  	}
  1450  }
  1451  
  1452  func listTests(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
  1453  	if _, err := matchString(*matchList, "non-empty"); err != nil {
  1454  		fmt.Fprintf(os.Stderr, "testing: invalid regexp in -test.list (%q): %s\n", *matchList, err)
  1455  		os.Exit(1)
  1456  	}
  1457  
  1458  	for _, test := range tests {
  1459  		if ok, _ := matchString(*matchList, test.Name); ok {
  1460  			fmt.Println(test.Name)
  1461  		}
  1462  	}
  1463  	for _, bench := range benchmarks {
  1464  		if ok, _ := matchString(*matchList, bench.Name); ok {
  1465  			fmt.Println(bench.Name)
  1466  		}
  1467  	}
  1468  	for _, example := range examples {
  1469  		if ok, _ := matchString(*matchList, example.Name); ok {
  1470  			fmt.Println(example.Name)
  1471  		}
  1472  	}
  1473  }
  1474  
  1475  // RunTests is an internal function but exported because it is cross-package;
  1476  // it is part of the implementation of the "go test" command.
  1477  func RunTests(matchString func(pat, str string) (bool, error), tests []InternalTest) (ok bool) {
  1478  	var deadline time.Time
  1479  	if *timeout > 0 {
  1480  		deadline = time.Now().Add(*timeout)
  1481  	}
  1482  	ran, ok := runTests(matchString, tests, deadline)
  1483  	if !ran && !haveExamples {
  1484  		fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
  1485  	}
  1486  	return ok
  1487  }
  1488  
  1489  func runTests(matchString func(pat, str string) (bool, error), tests []InternalTest, deadline time.Time) (ran, ok bool) {
  1490  	ok = true
  1491  	for _, procs := range cpuList {
  1492  		runtime.GOMAXPROCS(procs)
  1493  		for i := uint(0); i < *count; i++ {
  1494  			if shouldFailFast() {
  1495  				break
  1496  			}
  1497  			ctx := newTestContext(*parallel, newMatcher(matchString, *match, "-test.run"))
  1498  			ctx.deadline = deadline
  1499  			t := &T{
  1500  				common: common{
  1501  					signal:  make(chan bool),
  1502  					barrier: make(chan bool),
  1503  					w:       os.Stdout,
  1504  				},
  1505  				context: ctx,
  1506  			}
  1507  			if Verbose() {
  1508  				t.chatty = newChattyPrinter(t.w)
  1509  			}
  1510  			tRunner(t, func(t *T) {
  1511  				for _, test := range tests {
  1512  					t.Run(test.Name, test.F)
  1513  				}
  1514  				// Run catching the signal rather than the tRunner as a separate
  1515  				// goroutine to avoid adding a goroutine during the sequential
  1516  				// phase as this pollutes the stacktrace output when aborting.
  1517  				go func() { <-t.signal }()
  1518  			})
  1519  			ok = ok && !t.Failed()
  1520  			ran = ran || t.ran
  1521  		}
  1522  	}
  1523  	return ran, ok
  1524  }
  1525  
  1526  // before runs before all testing.
  1527  func (m *M) before() {
  1528  	if *memProfileRate > 0 {
  1529  		runtime.MemProfileRate = *memProfileRate
  1530  	}
  1531  	if *cpuProfile != "" {
  1532  		f, err := os.Create(toOutputDir(*cpuProfile))
  1533  		if err != nil {
  1534  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1535  			return
  1536  		}
  1537  		if err := m.deps.StartCPUProfile(f); err != nil {
  1538  			fmt.Fprintf(os.Stderr, "testing: can't start cpu profile: %s\n", err)
  1539  			f.Close()
  1540  			return
  1541  		}
  1542  		// Could save f so after can call f.Close; not worth the effort.
  1543  	}
  1544  	if *traceFile != "" {
  1545  		f, err := os.Create(toOutputDir(*traceFile))
  1546  		if err != nil {
  1547  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1548  			return
  1549  		}
  1550  		if err := trace.Start(f); err != nil {
  1551  			fmt.Fprintf(os.Stderr, "testing: can't start tracing: %s\n", err)
  1552  			f.Close()
  1553  			return
  1554  		}
  1555  		// Could save f so after can call f.Close; not worth the effort.
  1556  	}
  1557  	if *blockProfile != "" && *blockProfileRate >= 0 {
  1558  		runtime.SetBlockProfileRate(*blockProfileRate)
  1559  	}
  1560  	if *mutexProfile != "" && *mutexProfileFraction >= 0 {
  1561  		runtime.SetMutexProfileFraction(*mutexProfileFraction)
  1562  	}
  1563  	if *coverProfile != "" && cover.Mode == "" {
  1564  		fmt.Fprintf(os.Stderr, "testing: cannot use -test.coverprofile because test binary was not built with coverage enabled\n")
  1565  		os.Exit(2)
  1566  	}
  1567  	if *testlog != "" {
  1568  		// Note: Not using toOutputDir.
  1569  		// This file is for use by cmd/go, not users.
  1570  		var f *os.File
  1571  		var err error
  1572  		if m.numRun == 1 {
  1573  			f, err = os.Create(*testlog)
  1574  		} else {
  1575  			f, err = os.OpenFile(*testlog, os.O_WRONLY, 0)
  1576  			if err == nil {
  1577  				f.Seek(0, io.SeekEnd)
  1578  			}
  1579  		}
  1580  		if err != nil {
  1581  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1582  			os.Exit(2)
  1583  		}
  1584  		m.deps.StartTestLog(f)
  1585  		testlogFile = f
  1586  	}
  1587  	if *panicOnExit0 {
  1588  		m.deps.SetPanicOnExit0(true)
  1589  	}
  1590  }
  1591  
  1592  // after runs after all testing.
  1593  func (m *M) after() {
  1594  	m.afterOnce.Do(func() {
  1595  		m.writeProfiles()
  1596  	})
  1597  
  1598  	// Restore PanicOnExit0 after every run, because we set it to true before
  1599  	// every run. Otherwise, if m.Run is called multiple times the behavior of
  1600  	// os.Exit(0) will not be restored after the second run.
  1601  	if *panicOnExit0 {
  1602  		m.deps.SetPanicOnExit0(false)
  1603  	}
  1604  }
  1605  
  1606  func (m *M) writeProfiles() {
  1607  	if *testlog != "" {
  1608  		if err := m.deps.StopTestLog(); err != nil {
  1609  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, err)
  1610  			os.Exit(2)
  1611  		}
  1612  		if err := testlogFile.Close(); err != nil {
  1613  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, err)
  1614  			os.Exit(2)
  1615  		}
  1616  	}
  1617  	if *cpuProfile != "" {
  1618  		m.deps.StopCPUProfile() // flushes profile to disk
  1619  	}
  1620  	if *traceFile != "" {
  1621  		trace.Stop() // flushes trace to disk
  1622  	}
  1623  	if *memProfile != "" {
  1624  		f, err := os.Create(toOutputDir(*memProfile))
  1625  		if err != nil {
  1626  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1627  			os.Exit(2)
  1628  		}
  1629  		runtime.GC() // materialize all statistics
  1630  		if err = m.deps.WriteProfileTo("allocs", f, 0); err != nil {
  1631  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *memProfile, err)
  1632  			os.Exit(2)
  1633  		}
  1634  		f.Close()
  1635  	}
  1636  	if *blockProfile != "" && *blockProfileRate >= 0 {
  1637  		f, err := os.Create(toOutputDir(*blockProfile))
  1638  		if err != nil {
  1639  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1640  			os.Exit(2)
  1641  		}
  1642  		if err = m.deps.WriteProfileTo("block", f, 0); err != nil {
  1643  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *blockProfile, err)
  1644  			os.Exit(2)
  1645  		}
  1646  		f.Close()
  1647  	}
  1648  	if *mutexProfile != "" && *mutexProfileFraction >= 0 {
  1649  		f, err := os.Create(toOutputDir(*mutexProfile))
  1650  		if err != nil {
  1651  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1652  			os.Exit(2)
  1653  		}
  1654  		if err = m.deps.WriteProfileTo("mutex", f, 0); err != nil {
  1655  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *mutexProfile, err)
  1656  			os.Exit(2)
  1657  		}
  1658  		f.Close()
  1659  	}
  1660  	if cover.Mode != "" {
  1661  		coverReport()
  1662  	}
  1663  }
  1664  
  1665  // toOutputDir returns the file name relocated, if required, to outputDir.
  1666  // Simple implementation to avoid pulling in path/filepath.
  1667  func toOutputDir(path string) string {
  1668  	if *outputDir == "" || path == "" {
  1669  		return path
  1670  	}
  1671  	// On Windows, it's clumsy, but we can be almost always correct
  1672  	// by just looking for a drive letter and a colon.
  1673  	// Absolute paths always have a drive letter (ignoring UNC).
  1674  	// Problem: if path == "C:A" and outputdir == "C:\Go" it's unclear
  1675  	// what to do, but even then path/filepath doesn't help.
  1676  	// TODO: Worth doing better? Probably not, because we're here only
  1677  	// under the management of go test.
  1678  	if runtime.GOOS == "windows" && len(path) >= 2 {
  1679  		letter, colon := path[0], path[1]
  1680  		if ('a' <= letter && letter <= 'z' || 'A' <= letter && letter <= 'Z') && colon == ':' {
  1681  			// If path starts with a drive letter we're stuck with it regardless.
  1682  			return path
  1683  		}
  1684  	}
  1685  	if os.IsPathSeparator(path[0]) {
  1686  		return path
  1687  	}
  1688  	return fmt.Sprintf("%s%c%s", *outputDir, os.PathSeparator, path)
  1689  }
  1690  
  1691  // startAlarm starts an alarm if requested.
  1692  func (m *M) startAlarm() time.Time {
  1693  	if *timeout <= 0 {
  1694  		return time.Time{}
  1695  	}
  1696  
  1697  	deadline := time.Now().Add(*timeout)
  1698  	m.timer = time.AfterFunc(*timeout, func() {
  1699  		m.after()
  1700  		debug.SetTraceback("all")
  1701  		panic(fmt.Sprintf("test timed out after %v", *timeout))
  1702  	})
  1703  	return deadline
  1704  }
  1705  
  1706  // stopAlarm turns off the alarm.
  1707  func (m *M) stopAlarm() {
  1708  	if *timeout > 0 {
  1709  		m.timer.Stop()
  1710  	}
  1711  }
  1712  
  1713  func parseCpuList() {
  1714  	for _, val := range strings.Split(*cpuListStr, ",") {
  1715  		val = strings.TrimSpace(val)
  1716  		if val == "" {
  1717  			continue
  1718  		}
  1719  		cpu, err := strconv.Atoi(val)
  1720  		if err != nil || cpu <= 0 {
  1721  			fmt.Fprintf(os.Stderr, "testing: invalid value %q for -test.cpu\n", val)
  1722  			os.Exit(1)
  1723  		}
  1724  		cpuList = append(cpuList, cpu)
  1725  	}
  1726  	if cpuList == nil {
  1727  		cpuList = append(cpuList, runtime.GOMAXPROCS(-1))
  1728  	}
  1729  }
  1730  
  1731  func shouldFailFast() bool {
  1732  	return *failFast && atomic.LoadUint32(&numFailed) > 0
  1733  }
  1734  

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