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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  // Tests and benchmarks may be skipped if not applicable with a call to
    21  // the Skip method of *T and *B:
    22  //     func TestTimeConsuming(t *testing.T) {
    23  //         if testing.Short() {
    24  //             t.Skip("skipping test in short mode.")
    25  //         }
    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-Description_of_testing_flags.
    38  //
    39  // A sample benchmark function looks like this:
    40  //     func BenchmarkHello(b *testing.B) {
    41  //         for i := 0; i < b.N; i++ {
    42  //             fmt.Sprintf("hello")
    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  //     BenchmarkHello    10000000    282 ns/op
    50  // means that the loop ran 10000000 times at a speed of 282 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(4) {
   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  // Subtests and Sub-benchmarks
   136  //
   137  // The Run methods of T and B allow defining subtests and sub-benchmarks,
   138  // without having to define separate functions for each. This enables uses
   139  // like table-driven benchmarks and creating hierarchical tests.
   140  // It also provides a way to share common setup and tear-down code:
   141  //
   142  //     func TestFoo(t *testing.T) {
   143  //         // <setup code>
   144  //         t.Run("A=1", func(t *testing.T) { ... })
   145  //         t.Run("A=2", func(t *testing.T) { ... })
   146  //         t.Run("B=1", func(t *testing.T) { ... })
   147  //         // <tear-down code>
   148  //     }
   149  //
   150  // Each subtest and sub-benchmark has a unique name: the combination of the name
   151  // of the top-level test and the sequence of names passed to Run, separated by
   152  // slashes, with an optional trailing sequence number for disambiguation.
   153  //
   154  // The argument to the -run and -bench command-line flags is an unanchored regular
   155  // expression that matches the test's name. For tests with multiple slash-separated
   156  // elements, such as subtests, the argument is itself slash-separated, with
   157  // expressions matching each name element in turn. Because it is unanchored, an
   158  // empty expression matches any string.
   159  // For example, using "matching" to mean "whose name contains":
   160  //
   161  //     go test -run ''      # Run all tests.
   162  //     go test -run Foo     # Run top-level tests matching "Foo", such as "TestFooBar".
   163  //     go test -run Foo/A=  # For top-level tests matching "Foo", run subtests matching "A=".
   164  //     go test -run /A=1    # For all top-level tests, run subtests matching "A=1".
   165  //
   166  // Subtests can also be used to control parallelism. A parent test will only
   167  // complete once all of its subtests complete. In this example, all tests are
   168  // run in parallel with each other, and only with each other, regardless of
   169  // other top-level tests that may be defined:
   170  //
   171  //     func TestGroupedParallel(t *testing.T) {
   172  //         for _, tc := range tests {
   173  //             tc := tc // capture range variable
   174  //             t.Run(tc.Name, func(t *testing.T) {
   175  //                 t.Parallel()
   176  //                 ...
   177  //             })
   178  //         }
   179  //     }
   180  //
   181  // Run does not return until parallel subtests have completed, providing a way
   182  // to clean up after a group of parallel tests:
   183  //
   184  //     func TestTeardownParallel(t *testing.T) {
   185  //         // This Run will not return until the parallel tests finish.
   186  //         t.Run("group", func(t *testing.T) {
   187  //             t.Run("Test1", parallelTest1)
   188  //             t.Run("Test2", parallelTest2)
   189  //             t.Run("Test3", parallelTest3)
   190  //         })
   191  //         // <tear-down code>
   192  //     }
   193  //
   194  // Main
   195  //
   196  // It is sometimes necessary for a test program to do extra setup or teardown
   197  // before or after testing. It is also sometimes necessary for a test to control
   198  // which code runs on the main thread. To support these and other cases,
   199  // if a test file contains a function:
   200  //
   201  //	func TestMain(m *testing.M)
   202  //
   203  // then the generated test will call TestMain(m) instead of running the tests
   204  // directly. TestMain runs in the main goroutine and can do whatever setup
   205  // and teardown is necessary around a call to m.Run. It should then call
   206  // os.Exit with the result of m.Run. When TestMain is called, flag.Parse has
   207  // not been run. If TestMain depends on command-line flags, including those
   208  // of the testing package, it should call flag.Parse explicitly.
   209  //
   210  // A simple implementation of TestMain is:
   211  //
   212  //	func TestMain(m *testing.M) {
   213  //		// call flag.Parse() here if TestMain uses flags
   214  //		os.Exit(m.Run())
   215  //	}
   216  //
   217  package testing
   218  
   219  import (
   220  	"bytes"
   221  	"errors"
   222  	"flag"
   223  	"fmt"
   224  	"internal/race"
   225  	"io"
   226  	"os"
   227  	"runtime"
   228  	"runtime/debug"
   229  	"runtime/trace"
   230  	"strconv"
   231  	"strings"
   232  	"sync"
   233  	"sync/atomic"
   234  	"time"
   235  )
   236  
   237  var (
   238  	// The short flag requests that tests run more quickly, but its functionality
   239  	// is provided by test writers themselves. The testing package is just its
   240  	// home. The all.bash installation script sets it to make installation more
   241  	// efficient, but by default the flag is off so a plain "go test" will do a
   242  	// full test of the package.
   243  	short = flag.Bool("test.short", false, "run smaller test suite to save time")
   244  
   245  	// The failfast flag requests that test execution stop after the first test failure.
   246  	failFast = flag.Bool("test.failfast", false, "do not start new tests after the first test failure")
   247  
   248  	// The directory in which to create profile files and the like. When run from
   249  	// "go test", the binary always runs in the source directory for the package;
   250  	// this flag lets "go test" tell the binary to write the files in the directory where
   251  	// the "go test" command is run.
   252  	outputDir = flag.String("test.outputdir", "", "write profiles to `dir`")
   253  
   254  	// Report as tests are run; default is silent for success.
   255  	chatty               = flag.Bool("test.v", false, "verbose: print additional output")
   256  	count                = flag.Uint("test.count", 1, "run tests and benchmarks `n` times")
   257  	coverProfile         = flag.String("test.coverprofile", "", "write a coverage profile to `file`")
   258  	matchList            = flag.String("test.list", "", "list tests, examples, and benchmarks matching `regexp` then exit")
   259  	match                = flag.String("test.run", "", "run only tests and examples matching `regexp`")
   260  	memProfile           = flag.String("test.memprofile", "", "write a memory profile to `file`")
   261  	memProfileRate       = flag.Int("test.memprofilerate", 0, "set memory profiling `rate` (see runtime.MemProfileRate)")
   262  	cpuProfile           = flag.String("test.cpuprofile", "", "write a cpu profile to `file`")
   263  	blockProfile         = flag.String("test.blockprofile", "", "write a goroutine blocking profile to `file`")
   264  	blockProfileRate     = flag.Int("test.blockprofilerate", 1, "set blocking profile `rate` (see runtime.SetBlockProfileRate)")
   265  	mutexProfile         = flag.String("test.mutexprofile", "", "write a mutex contention profile to the named file after execution")
   266  	mutexProfileFraction = flag.Int("test.mutexprofilefraction", 1, "if >= 0, calls runtime.SetMutexProfileFraction()")
   267  	traceFile            = flag.String("test.trace", "", "write an execution trace to `file`")
   268  	timeout              = flag.Duration("test.timeout", 0, "panic test binary after duration `d` (default 0, timeout disabled)")
   269  	cpuListStr           = flag.String("test.cpu", "", "comma-separated `list` of cpu counts to run each test with")
   270  	parallel             = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "run at most `n` tests in parallel")
   271  	testlog              = flag.String("test.testlogfile", "", "write test action log to `file` (for use only by cmd/go)")
   272  
   273  	haveExamples bool // are there examples?
   274  
   275  	cpuList     []int
   276  	testlogFile *os.File
   277  
   278  	numFailed uint32 // number of test failures
   279  )
   280  
   281  // common holds the elements common between T and B and
   282  // captures common methods such as Errorf.
   283  type common struct {
   284  	mu      sync.RWMutex        // guards this group of fields
   285  	output  []byte              // Output generated by test or benchmark.
   286  	w       io.Writer           // For flushToParent.
   287  	ran     bool                // Test or benchmark (or one of its subtests) was executed.
   288  	failed  bool                // Test or benchmark has failed.
   289  	skipped bool                // Test of benchmark has been skipped.
   290  	done    bool                // Test is finished and all subtests have completed.
   291  	helpers map[string]struct{} // functions to be skipped when writing file/line info
   292  
   293  	chatty     bool   // A copy of the chatty flag.
   294  	finished   bool   // Test function has completed.
   295  	hasSub     int32  // written atomically
   296  	raceErrors int    // number of races detected during test
   297  	runner     string // function name of tRunner running the test
   298  
   299  	parent   *common
   300  	level    int       // Nesting depth of test or benchmark.
   301  	name     string    // Name of test or benchmark.
   302  	start    time.Time // Time test or benchmark started
   303  	duration time.Duration
   304  	barrier  chan bool // To signal parallel subtests they may start.
   305  	signal   chan bool // To signal a test is done.
   306  	sub      []*T      // Queue of subtests to be run in parallel.
   307  }
   308  
   309  // Short reports whether the -test.short flag is set.
   310  func Short() bool {
   311  	return *short
   312  }
   313  
   314  // CoverMode reports what the test coverage mode is set to. The
   315  // values are "set", "count", or "atomic". The return value will be
   316  // empty if test coverage is not enabled.
   317  func CoverMode() string {
   318  	return cover.Mode
   319  }
   320  
   321  // Verbose reports whether the -test.v flag is set.
   322  func Verbose() bool {
   323  	return *chatty
   324  }
   325  
   326  // frameSkip searches, starting after skip frames, for the first caller frame
   327  // in a function not marked as a helper and returns the frames to skip
   328  // to reach that site. The search stops if it finds a tRunner function that
   329  // was the entry point into the test.
   330  // This function must be called with c.mu held.
   331  func (c *common) frameSkip(skip int) int {
   332  	if c.helpers == nil {
   333  		return skip
   334  	}
   335  	var pc [50]uintptr
   336  	// Skip two extra frames to account for this function
   337  	// and runtime.Callers itself.
   338  	n := runtime.Callers(skip+2, pc[:])
   339  	if n == 0 {
   340  		panic("testing: zero callers found")
   341  	}
   342  	frames := runtime.CallersFrames(pc[:n])
   343  	var frame runtime.Frame
   344  	more := true
   345  	for i := 0; more; i++ {
   346  		frame, more = frames.Next()
   347  		if frame.Function == c.runner {
   348  			// We've gone up all the way to the tRunner calling
   349  			// the test function (so the user must have
   350  			// called tb.Helper from inside that test function).
   351  			// Only skip up to the test function itself.
   352  			return skip + i - 1
   353  		}
   354  		if _, ok := c.helpers[frame.Function]; !ok {
   355  			// Found a frame that wasn't inside a helper function.
   356  			return skip + i
   357  		}
   358  	}
   359  	return skip
   360  }
   361  
   362  // decorate prefixes the string with the file and line of the call site
   363  // and inserts the final newline if needed and indentation tabs for formatting.
   364  // This function must be called with c.mu held.
   365  func (c *common) decorate(s string) string {
   366  	skip := c.frameSkip(3) // decorate + log + public function.
   367  	_, file, line, ok := runtime.Caller(skip)
   368  	if ok {
   369  		// Truncate file name at last file name separator.
   370  		if index := strings.LastIndex(file, "/"); index >= 0 {
   371  			file = file[index+1:]
   372  		} else if index = strings.LastIndex(file, "\\"); index >= 0 {
   373  			file = file[index+1:]
   374  		}
   375  	} else {
   376  		file = "???"
   377  		line = 1
   378  	}
   379  	buf := new(bytes.Buffer)
   380  	// Every line is indented at least one tab.
   381  	buf.WriteByte('\t')
   382  	fmt.Fprintf(buf, "%s:%d: ", file, line)
   383  	lines := strings.Split(s, "\n")
   384  	if l := len(lines); l > 1 && lines[l-1] == "" {
   385  		lines = lines[:l-1]
   386  	}
   387  	for i, line := range lines {
   388  		if i > 0 {
   389  			// Second and subsequent lines are indented an extra tab.
   390  			buf.WriteString("\n\t\t")
   391  		}
   392  		buf.WriteString(line)
   393  	}
   394  	buf.WriteByte('\n')
   395  	return buf.String()
   396  }
   397  
   398  // flushToParent writes c.output to the parent after first writing the header
   399  // with the given format and arguments.
   400  func (c *common) flushToParent(format string, args ...interface{}) {
   401  	p := c.parent
   402  	p.mu.Lock()
   403  	defer p.mu.Unlock()
   404  
   405  	fmt.Fprintf(p.w, format, args...)
   406  
   407  	c.mu.Lock()
   408  	defer c.mu.Unlock()
   409  	io.Copy(p.w, bytes.NewReader(c.output))
   410  	c.output = c.output[:0]
   411  }
   412  
   413  type indenter struct {
   414  	c *common
   415  }
   416  
   417  func (w indenter) Write(b []byte) (n int, err error) {
   418  	n = len(b)
   419  	for len(b) > 0 {
   420  		end := bytes.IndexByte(b, '\n')
   421  		if end == -1 {
   422  			end = len(b)
   423  		} else {
   424  			end++
   425  		}
   426  		// An indent of 4 spaces will neatly align the dashes with the status
   427  		// indicator of the parent.
   428  		const indent = "    "
   429  		w.c.output = append(w.c.output, indent...)
   430  		w.c.output = append(w.c.output, b[:end]...)
   431  		b = b[end:]
   432  	}
   433  	return
   434  }
   435  
   436  // fmtDuration returns a string representing d in the form "87.00s".
   437  func fmtDuration(d time.Duration) string {
   438  	return fmt.Sprintf("%.2fs", d.Seconds())
   439  }
   440  
   441  // TB is the interface common to T and B.
   442  type TB interface {
   443  	Error(args ...interface{})
   444  	Errorf(format string, args ...interface{})
   445  	Fail()
   446  	FailNow()
   447  	Failed() bool
   448  	Fatal(args ...interface{})
   449  	Fatalf(format string, args ...interface{})
   450  	Log(args ...interface{})
   451  	Logf(format string, args ...interface{})
   452  	Name() string
   453  	Skip(args ...interface{})
   454  	SkipNow()
   455  	Skipf(format string, args ...interface{})
   456  	Skipped() bool
   457  	Helper()
   458  
   459  	// A private method to prevent users implementing the
   460  	// interface and so future additions to it will not
   461  	// violate Go 1 compatibility.
   462  	private()
   463  }
   464  
   465  var _ TB = (*T)(nil)
   466  var _ TB = (*B)(nil)
   467  
   468  // T is a type passed to Test functions to manage test state and support formatted test logs.
   469  // Logs are accumulated during execution and dumped to standard output when done.
   470  //
   471  // A test ends when its Test function returns or calls any of the methods
   472  // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods, as well as
   473  // the Parallel method, must be called only from the goroutine running the
   474  // Test function.
   475  //
   476  // The other reporting methods, such as the variations of Log and Error,
   477  // may be called simultaneously from multiple goroutines.
   478  type T struct {
   479  	common
   480  	isParallel bool
   481  	context    *testContext // For running tests and subtests.
   482  }
   483  
   484  func (c *common) private() {}
   485  
   486  // Name returns the name of the running test or benchmark.
   487  func (c *common) Name() string {
   488  	return c.name
   489  }
   490  
   491  func (c *common) setRan() {
   492  	if c.parent != nil {
   493  		c.parent.setRan()
   494  	}
   495  	c.mu.Lock()
   496  	defer c.mu.Unlock()
   497  	c.ran = true
   498  }
   499  
   500  // Fail marks the function as having failed but continues execution.
   501  func (c *common) Fail() {
   502  	if c.parent != nil {
   503  		c.parent.Fail()
   504  	}
   505  	c.mu.Lock()
   506  	defer c.mu.Unlock()
   507  	// c.done needs to be locked to synchronize checks to c.done in parent tests.
   508  	if c.done {
   509  		panic("Fail in goroutine after " + c.name + " has completed")
   510  	}
   511  	c.failed = true
   512  }
   513  
   514  // Failed reports whether the function has failed.
   515  func (c *common) Failed() bool {
   516  	c.mu.RLock()
   517  	failed := c.failed
   518  	c.mu.RUnlock()
   519  	return failed || c.raceErrors+race.Errors() > 0
   520  }
   521  
   522  // FailNow marks the function as having failed and stops its execution
   523  // by calling runtime.Goexit (which then runs all deferred calls in the
   524  // current goroutine).
   525  // Execution will continue at the next test or benchmark.
   526  // FailNow must be called from the goroutine running the
   527  // test or benchmark function, not from other goroutines
   528  // created during the test. Calling FailNow does not stop
   529  // those other goroutines.
   530  func (c *common) FailNow() {
   531  	c.Fail()
   532  
   533  	// Calling runtime.Goexit will exit the goroutine, which
   534  	// will run the deferred functions in this goroutine,
   535  	// which will eventually run the deferred lines in tRunner,
   536  	// which will signal to the test loop that this test is done.
   537  	//
   538  	// A previous version of this code said:
   539  	//
   540  	//	c.duration = ...
   541  	//	c.signal <- c.self
   542  	//	runtime.Goexit()
   543  	//
   544  	// This previous version duplicated code (those lines are in
   545  	// tRunner no matter what), but worse the goroutine teardown
   546  	// implicit in runtime.Goexit was not guaranteed to complete
   547  	// before the test exited. If a test deferred an important cleanup
   548  	// function (like removing temporary files), there was no guarantee
   549  	// it would run on a test failure. Because we send on c.signal during
   550  	// a top-of-stack deferred function now, we know that the send
   551  	// only happens after any other stacked defers have completed.
   552  	c.finished = true
   553  	runtime.Goexit()
   554  }
   555  
   556  // log generates the output. It's always at the same stack depth.
   557  func (c *common) log(s string) {
   558  	c.mu.Lock()
   559  	defer c.mu.Unlock()
   560  	c.output = append(c.output, c.decorate(s)...)
   561  }
   562  
   563  // Log formats its arguments using default formatting, analogous to Println,
   564  // and records the text in the error log. For tests, the text will be printed only if
   565  // the test fails or the -test.v flag is set. For benchmarks, the text is always
   566  // printed to avoid having performance depend on the value of the -test.v flag.
   567  func (c *common) Log(args ...interface{}) { c.log(fmt.Sprintln(args...)) }
   568  
   569  // Logf formats its arguments according to the format, analogous to Printf, and
   570  // records the text in the error log. A final newline is added if not provided. For
   571  // tests, the text will be printed only if the test fails or the -test.v flag is
   572  // set. For benchmarks, the text is always printed to avoid having performance
   573  // depend on the value of the -test.v flag.
   574  func (c *common) Logf(format string, args ...interface{}) { c.log(fmt.Sprintf(format, args...)) }
   575  
   576  // Error is equivalent to Log followed by Fail.
   577  func (c *common) Error(args ...interface{}) {
   578  	c.log(fmt.Sprintln(args...))
   579  	c.Fail()
   580  }
   581  
   582  // Errorf is equivalent to Logf followed by Fail.
   583  func (c *common) Errorf(format string, args ...interface{}) {
   584  	c.log(fmt.Sprintf(format, args...))
   585  	c.Fail()
   586  }
   587  
   588  // Fatal is equivalent to Log followed by FailNow.
   589  func (c *common) Fatal(args ...interface{}) {
   590  	c.log(fmt.Sprintln(args...))
   591  	c.FailNow()
   592  }
   593  
   594  // Fatalf is equivalent to Logf followed by FailNow.
   595  func (c *common) Fatalf(format string, args ...interface{}) {
   596  	c.log(fmt.Sprintf(format, args...))
   597  	c.FailNow()
   598  }
   599  
   600  // Skip is equivalent to Log followed by SkipNow.
   601  func (c *common) Skip(args ...interface{}) {
   602  	c.log(fmt.Sprintln(args...))
   603  	c.SkipNow()
   604  }
   605  
   606  // Skipf is equivalent to Logf followed by SkipNow.
   607  func (c *common) Skipf(format string, args ...interface{}) {
   608  	c.log(fmt.Sprintf(format, args...))
   609  	c.SkipNow()
   610  }
   611  
   612  // SkipNow marks the test as having been skipped and stops its execution
   613  // by calling runtime.Goexit.
   614  // If a test fails (see Error, Errorf, Fail) and is then skipped,
   615  // it is still considered to have failed.
   616  // Execution will continue at the next test or benchmark. See also FailNow.
   617  // SkipNow must be called from the goroutine running the test, not from
   618  // other goroutines created during the test. Calling SkipNow does not stop
   619  // those other goroutines.
   620  func (c *common) SkipNow() {
   621  	c.skip()
   622  	c.finished = true
   623  	runtime.Goexit()
   624  }
   625  
   626  func (c *common) skip() {
   627  	c.mu.Lock()
   628  	defer c.mu.Unlock()
   629  	c.skipped = true
   630  }
   631  
   632  // Skipped reports whether the test was skipped.
   633  func (c *common) Skipped() bool {
   634  	c.mu.RLock()
   635  	defer c.mu.RUnlock()
   636  	return c.skipped
   637  }
   638  
   639  // Helper marks the calling function as a test helper function.
   640  // When printing file and line information, that function will be skipped.
   641  // Helper may be called simultaneously from multiple goroutines.
   642  // Helper has no effect if it is called directly from a TestXxx/BenchmarkXxx
   643  // function or a subtest/sub-benchmark function.
   644  func (c *common) Helper() {
   645  	c.mu.Lock()
   646  	defer c.mu.Unlock()
   647  	if c.helpers == nil {
   648  		c.helpers = make(map[string]struct{})
   649  	}
   650  	c.helpers[callerName(1)] = struct{}{}
   651  }
   652  
   653  // callerName gives the function name (qualified with a package path)
   654  // for the caller after skip frames (where 0 means the current function).
   655  func callerName(skip int) string {
   656  	// Make room for the skip PC.
   657  	var pc [2]uintptr
   658  	n := runtime.Callers(skip+2, pc[:]) // skip + runtime.Callers + callerName
   659  	if n == 0 {
   660  		panic("testing: zero callers found")
   661  	}
   662  	frames := runtime.CallersFrames(pc[:n])
   663  	frame, _ := frames.Next()
   664  	return frame.Function
   665  }
   666  
   667  // Parallel signals that this test is to be run in parallel with (and only with)
   668  // other parallel tests. When a test is run multiple times due to use of
   669  // -test.count or -test.cpu, multiple instances of a single test never run in
   670  // parallel with each other.
   671  func (t *T) Parallel() {
   672  	if t.isParallel {
   673  		panic("testing: t.Parallel called multiple times")
   674  	}
   675  	t.isParallel = true
   676  
   677  	// We don't want to include the time we spend waiting for serial tests
   678  	// in the test duration. Record the elapsed time thus far and reset the
   679  	// timer afterwards.
   680  	t.duration += time.Since(t.start)
   681  
   682  	// Add to the list of tests to be released by the parent.
   683  	t.parent.sub = append(t.parent.sub, t)
   684  	t.raceErrors += race.Errors()
   685  
   686  	if t.chatty {
   687  		// Print directly to root's io.Writer so there is no delay.
   688  		root := t.parent
   689  		for ; root.parent != nil; root = root.parent {
   690  		}
   691  		root.mu.Lock()
   692  		fmt.Fprintf(root.w, "=== PAUSE %s\n", t.name)
   693  		root.mu.Unlock()
   694  	}
   695  
   696  	t.signal <- true   // Release calling test.
   697  	<-t.parent.barrier // Wait for the parent test to complete.
   698  	t.context.waitParallel()
   699  
   700  	if t.chatty {
   701  		// Print directly to root's io.Writer so there is no delay.
   702  		root := t.parent
   703  		for ; root.parent != nil; root = root.parent {
   704  		}
   705  		root.mu.Lock()
   706  		fmt.Fprintf(root.w, "=== CONT  %s\n", t.name)
   707  		root.mu.Unlock()
   708  	}
   709  
   710  	t.start = time.Now()
   711  	t.raceErrors += -race.Errors()
   712  }
   713  
   714  // An internal type but exported because it is cross-package; part of the implementation
   715  // of the "go test" command.
   716  type InternalTest struct {
   717  	Name string
   718  	F    func(*T)
   719  }
   720  
   721  func tRunner(t *T, fn func(t *T)) {
   722  	t.runner = callerName(0)
   723  
   724  	// When this goroutine is done, either because fn(t)
   725  	// returned normally or because a test failure triggered
   726  	// a call to runtime.Goexit, record the duration and send
   727  	// a signal saying that the test is done.
   728  	defer func() {
   729  		if t.raceErrors+race.Errors() > 0 {
   730  			t.Errorf("race detected during execution of test")
   731  		}
   732  
   733  		t.duration += time.Since(t.start)
   734  		// If the test panicked, print any test output before dying.
   735  		err := recover()
   736  		if !t.finished && err == nil {
   737  			err = fmt.Errorf("test executed panic(nil) or runtime.Goexit")
   738  		}
   739  		if err != nil {
   740  			t.Fail()
   741  			t.report()
   742  			panic(err)
   743  		}
   744  
   745  		if len(t.sub) > 0 {
   746  			// Run parallel subtests.
   747  			// Decrease the running count for this test.
   748  			t.context.release()
   749  			// Release the parallel subtests.
   750  			close(t.barrier)
   751  			// Wait for subtests to complete.
   752  			for _, sub := range t.sub {
   753  				<-sub.signal
   754  			}
   755  			if !t.isParallel {
   756  				// Reacquire the count for sequential tests. See comment in Run.
   757  				t.context.waitParallel()
   758  			}
   759  		} else if t.isParallel {
   760  			// Only release the count for this test if it was run as a parallel
   761  			// test. See comment in Run method.
   762  			t.context.release()
   763  		}
   764  		t.report() // Report after all subtests have finished.
   765  
   766  		// Do not lock t.done to allow race detector to detect race in case
   767  		// the user does not appropriately synchronizes a goroutine.
   768  		t.done = true
   769  		if t.parent != nil && atomic.LoadInt32(&t.hasSub) == 0 {
   770  			t.setRan()
   771  		}
   772  		t.signal <- true
   773  	}()
   774  
   775  	t.start = time.Now()
   776  	t.raceErrors = -race.Errors()
   777  	fn(t)
   778  
   779  	if t.failed {
   780  		atomic.AddUint32(&numFailed, 1)
   781  	}
   782  	t.finished = true
   783  }
   784  
   785  // Run runs f as a subtest of t called name. It runs f in a separate goroutine
   786  // and blocks until f returns or calls t.Parallel to become a parallel test.
   787  // Run reports whether f succeeded (or at least did not fail before calling t.Parallel).
   788  //
   789  // Run may be called simultaneously from multiple goroutines, but all such calls
   790  // must return before the outer test function for t returns.
   791  func (t *T) Run(name string, f func(t *T)) bool {
   792  	atomic.StoreInt32(&t.hasSub, 1)
   793  	testName, ok, _ := t.context.match.fullName(&t.common, name)
   794  	if !ok || shouldFailFast() {
   795  		return true
   796  	}
   797  	t = &T{
   798  		common: common{
   799  			barrier: make(chan bool),
   800  			signal:  make(chan bool),
   801  			name:    testName,
   802  			parent:  &t.common,
   803  			level:   t.level + 1,
   804  			chatty:  t.chatty,
   805  		},
   806  		context: t.context,
   807  	}
   808  	t.w = indenter{&t.common}
   809  
   810  	if t.chatty {
   811  		// Print directly to root's io.Writer so there is no delay.
   812  		root := t.parent
   813  		for ; root.parent != nil; root = root.parent {
   814  		}
   815  		root.mu.Lock()
   816  		fmt.Fprintf(root.w, "=== RUN   %s\n", t.name)
   817  		root.mu.Unlock()
   818  	}
   819  	// Instead of reducing the running count of this test before calling the
   820  	// tRunner and increasing it afterwards, we rely on tRunner keeping the
   821  	// count correct. This ensures that a sequence of sequential tests runs
   822  	// without being preempted, even when their parent is a parallel test. This
   823  	// may especially reduce surprises if *parallel == 1.
   824  	go tRunner(t, f)
   825  	<-t.signal
   826  	return !t.failed
   827  }
   828  
   829  // testContext holds all fields that are common to all tests. This includes
   830  // synchronization primitives to run at most *parallel tests.
   831  type testContext struct {
   832  	match *matcher
   833  
   834  	mu sync.Mutex
   835  
   836  	// Channel used to signal tests that are ready to be run in parallel.
   837  	startParallel chan bool
   838  
   839  	// running is the number of tests currently running in parallel.
   840  	// This does not include tests that are waiting for subtests to complete.
   841  	running int
   842  
   843  	// numWaiting is the number tests waiting to be run in parallel.
   844  	numWaiting int
   845  
   846  	// maxParallel is a copy of the parallel flag.
   847  	maxParallel int
   848  }
   849  
   850  func newTestContext(maxParallel int, m *matcher) *testContext {
   851  	return &testContext{
   852  		match:         m,
   853  		startParallel: make(chan bool),
   854  		maxParallel:   maxParallel,
   855  		running:       1, // Set the count to 1 for the main (sequential) test.
   856  	}
   857  }
   858  
   859  func (c *testContext) waitParallel() {
   860  	c.mu.Lock()
   861  	if c.running < c.maxParallel {
   862  		c.running++
   863  		c.mu.Unlock()
   864  		return
   865  	}
   866  	c.numWaiting++
   867  	c.mu.Unlock()
   868  	<-c.startParallel
   869  }
   870  
   871  func (c *testContext) release() {
   872  	c.mu.Lock()
   873  	if c.numWaiting == 0 {
   874  		c.running--
   875  		c.mu.Unlock()
   876  		return
   877  	}
   878  	c.numWaiting--
   879  	c.mu.Unlock()
   880  	c.startParallel <- true // Pick a waiting test to be run.
   881  }
   882  
   883  // No one should be using func Main anymore.
   884  // See the doc comment on func Main and use MainStart instead.
   885  var errMain = errors.New("testing: unexpected use of func Main")
   886  
   887  type matchStringOnly func(pat, str string) (bool, error)
   888  
   889  func (f matchStringOnly) MatchString(pat, str string) (bool, error)   { return f(pat, str) }
   890  func (f matchStringOnly) StartCPUProfile(w io.Writer) error           { return errMain }
   891  func (f matchStringOnly) StopCPUProfile()                             {}
   892  func (f matchStringOnly) WriteHeapProfile(w io.Writer) error          { return errMain }
   893  func (f matchStringOnly) WriteProfileTo(string, io.Writer, int) error { return errMain }
   894  func (f matchStringOnly) ImportPath() string                          { return "" }
   895  func (f matchStringOnly) StartTestLog(io.Writer)                      {}
   896  func (f matchStringOnly) StopTestLog() error                          { return errMain }
   897  
   898  // Main is an internal function, part of the implementation of the "go test" command.
   899  // It was exported because it is cross-package and predates "internal" packages.
   900  // It is no longer used by "go test" but preserved, as much as possible, for other
   901  // systems that simulate "go test" using Main, but Main sometimes cannot be updated as
   902  // new functionality is added to the testing package.
   903  // Systems simulating "go test" should be updated to use MainStart.
   904  func Main(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
   905  	os.Exit(MainStart(matchStringOnly(matchString), tests, benchmarks, examples).Run())
   906  }
   907  
   908  // M is a type passed to a TestMain function to run the actual tests.
   909  type M struct {
   910  	deps       testDeps
   911  	tests      []InternalTest
   912  	benchmarks []InternalBenchmark
   913  	examples   []InternalExample
   914  
   915  	timer     *time.Timer
   916  	afterOnce sync.Once
   917  
   918  	numRun int
   919  }
   920  
   921  // testDeps is an internal interface of functionality that is
   922  // passed into this package by a test's generated main package.
   923  // The canonical implementation of this interface is
   924  // testing/internal/testdeps's TestDeps.
   925  type testDeps interface {
   926  	ImportPath() string
   927  	MatchString(pat, str string) (bool, error)
   928  	StartCPUProfile(io.Writer) error
   929  	StopCPUProfile()
   930  	StartTestLog(io.Writer)
   931  	StopTestLog() error
   932  	WriteHeapProfile(io.Writer) error
   933  	WriteProfileTo(string, io.Writer, int) error
   934  }
   935  
   936  // MainStart is meant for use by tests generated by 'go test'.
   937  // It is not meant to be called directly and is not subject to the Go 1 compatibility document.
   938  // It may change signature from release to release.
   939  func MainStart(deps testDeps, tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) *M {
   940  	return &M{
   941  		deps:       deps,
   942  		tests:      tests,
   943  		benchmarks: benchmarks,
   944  		examples:   examples,
   945  	}
   946  }
   947  
   948  // Run runs the tests. It returns an exit code to pass to os.Exit.
   949  func (m *M) Run() int {
   950  	// Count the number of calls to m.Run.
   951  	// We only ever expected 1, but we didn't enforce that,
   952  	// and now there are tests in the wild that call m.Run multiple times.
   953  	// Sigh. golang.org/issue/23129.
   954  	m.numRun++
   955  
   956  	// TestMain may have already called flag.Parse.
   957  	if !flag.Parsed() {
   958  		flag.Parse()
   959  	}
   960  
   961  	if *parallel < 1 {
   962  		fmt.Fprintln(os.Stderr, "testing: -parallel can only be given a positive integer")
   963  		flag.Usage()
   964  		return 2
   965  	}
   966  
   967  	if len(*matchList) != 0 {
   968  		listTests(m.deps.MatchString, m.tests, m.benchmarks, m.examples)
   969  		return 0
   970  	}
   971  
   972  	parseCpuList()
   973  
   974  	m.before()
   975  	defer m.after()
   976  	m.startAlarm()
   977  	haveExamples = len(m.examples) > 0
   978  	testRan, testOk := runTests(m.deps.MatchString, m.tests)
   979  	exampleRan, exampleOk := runExamples(m.deps.MatchString, m.examples)
   980  	m.stopAlarm()
   981  	if !testRan && !exampleRan && *matchBenchmarks == "" {
   982  		fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
   983  	}
   984  	if !testOk || !exampleOk || !runBenchmarks(m.deps.ImportPath(), m.deps.MatchString, m.benchmarks) || race.Errors() > 0 {
   985  		fmt.Println("FAIL")
   986  		return 1
   987  	}
   988  
   989  	fmt.Println("PASS")
   990  	return 0
   991  }
   992  
   993  func (t *T) report() {
   994  	if t.parent == nil {
   995  		return
   996  	}
   997  	dstr := fmtDuration(t.duration)
   998  	format := "--- %s: %s (%s)\n"
   999  	if t.Failed() {
  1000  		t.flushToParent(format, "FAIL", t.name, dstr)
  1001  	} else if t.chatty {
  1002  		if t.Skipped() {
  1003  			t.flushToParent(format, "SKIP", t.name, dstr)
  1004  		} else {
  1005  			t.flushToParent(format, "PASS", t.name, dstr)
  1006  		}
  1007  	}
  1008  }
  1009  
  1010  func listTests(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
  1011  	if _, err := matchString(*matchList, "non-empty"); err != nil {
  1012  		fmt.Fprintf(os.Stderr, "testing: invalid regexp in -test.list (%q): %s\n", *matchList, err)
  1013  		os.Exit(1)
  1014  	}
  1015  
  1016  	for _, test := range tests {
  1017  		if ok, _ := matchString(*matchList, test.Name); ok {
  1018  			fmt.Println(test.Name)
  1019  		}
  1020  	}
  1021  	for _, bench := range benchmarks {
  1022  		if ok, _ := matchString(*matchList, bench.Name); ok {
  1023  			fmt.Println(bench.Name)
  1024  		}
  1025  	}
  1026  	for _, example := range examples {
  1027  		if ok, _ := matchString(*matchList, example.Name); ok {
  1028  			fmt.Println(example.Name)
  1029  		}
  1030  	}
  1031  }
  1032  
  1033  // An internal function but exported because it is cross-package; part of the implementation
  1034  // of the "go test" command.
  1035  func RunTests(matchString func(pat, str string) (bool, error), tests []InternalTest) (ok bool) {
  1036  	ran, ok := runTests(matchString, tests)
  1037  	if !ran && !haveExamples {
  1038  		fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
  1039  	}
  1040  	return ok
  1041  }
  1042  
  1043  func runTests(matchString func(pat, str string) (bool, error), tests []InternalTest) (ran, ok bool) {
  1044  	ok = true
  1045  	for _, procs := range cpuList {
  1046  		runtime.GOMAXPROCS(procs)
  1047  		for i := uint(0); i < *count; i++ {
  1048  			if shouldFailFast() {
  1049  				break
  1050  			}
  1051  			ctx := newTestContext(*parallel, newMatcher(matchString, *match, "-test.run"))
  1052  			t := &T{
  1053  				common: common{
  1054  					signal:  make(chan bool),
  1055  					barrier: make(chan bool),
  1056  					w:       os.Stdout,
  1057  					chatty:  *chatty,
  1058  				},
  1059  				context: ctx,
  1060  			}
  1061  			tRunner(t, func(t *T) {
  1062  				for _, test := range tests {
  1063  					t.Run(test.Name, test.F)
  1064  				}
  1065  				// Run catching the signal rather than the tRunner as a separate
  1066  				// goroutine to avoid adding a goroutine during the sequential
  1067  				// phase as this pollutes the stacktrace output when aborting.
  1068  				go func() { <-t.signal }()
  1069  			})
  1070  			ok = ok && !t.Failed()
  1071  			ran = ran || t.ran
  1072  		}
  1073  	}
  1074  	return ran, ok
  1075  }
  1076  
  1077  // before runs before all testing.
  1078  func (m *M) before() {
  1079  	if *memProfileRate > 0 {
  1080  		runtime.MemProfileRate = *memProfileRate
  1081  	}
  1082  	if *cpuProfile != "" {
  1083  		f, err := os.Create(toOutputDir(*cpuProfile))
  1084  		if err != nil {
  1085  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1086  			return
  1087  		}
  1088  		if err := m.deps.StartCPUProfile(f); err != nil {
  1089  			fmt.Fprintf(os.Stderr, "testing: can't start cpu profile: %s\n", err)
  1090  			f.Close()
  1091  			return
  1092  		}
  1093  		// Could save f so after can call f.Close; not worth the effort.
  1094  	}
  1095  	if *traceFile != "" {
  1096  		f, err := os.Create(toOutputDir(*traceFile))
  1097  		if err != nil {
  1098  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1099  			return
  1100  		}
  1101  		if err := trace.Start(f); err != nil {
  1102  			fmt.Fprintf(os.Stderr, "testing: can't start tracing: %s\n", err)
  1103  			f.Close()
  1104  			return
  1105  		}
  1106  		// Could save f so after can call f.Close; not worth the effort.
  1107  	}
  1108  	if *blockProfile != "" && *blockProfileRate >= 0 {
  1109  		runtime.SetBlockProfileRate(*blockProfileRate)
  1110  	}
  1111  	if *mutexProfile != "" && *mutexProfileFraction >= 0 {
  1112  		runtime.SetMutexProfileFraction(*mutexProfileFraction)
  1113  	}
  1114  	if *coverProfile != "" && cover.Mode == "" {
  1115  		fmt.Fprintf(os.Stderr, "testing: cannot use -test.coverprofile because test binary was not built with coverage enabled\n")
  1116  		os.Exit(2)
  1117  	}
  1118  	if *testlog != "" {
  1119  		// Note: Not using toOutputDir.
  1120  		// This file is for use by cmd/go, not users.
  1121  		var f *os.File
  1122  		var err error
  1123  		if m.numRun == 1 {
  1124  			f, err = os.Create(*testlog)
  1125  		} else {
  1126  			f, err = os.OpenFile(*testlog, os.O_WRONLY, 0)
  1127  			if err == nil {
  1128  				f.Seek(0, io.SeekEnd)
  1129  			}
  1130  		}
  1131  		if err != nil {
  1132  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1133  			os.Exit(2)
  1134  		}
  1135  		m.deps.StartTestLog(f)
  1136  		testlogFile = f
  1137  	}
  1138  }
  1139  
  1140  // after runs after all testing.
  1141  func (m *M) after() {
  1142  	m.afterOnce.Do(func() {
  1143  		m.writeProfiles()
  1144  	})
  1145  }
  1146  
  1147  func (m *M) writeProfiles() {
  1148  	if *testlog != "" {
  1149  		if err := m.deps.StopTestLog(); err != nil {
  1150  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, err)
  1151  			os.Exit(2)
  1152  		}
  1153  		if err := testlogFile.Close(); err != nil {
  1154  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *testlog, err)
  1155  			os.Exit(2)
  1156  		}
  1157  	}
  1158  	if *cpuProfile != "" {
  1159  		m.deps.StopCPUProfile() // flushes profile to disk
  1160  	}
  1161  	if *traceFile != "" {
  1162  		trace.Stop() // flushes trace to disk
  1163  	}
  1164  	if *memProfile != "" {
  1165  		f, err := os.Create(toOutputDir(*memProfile))
  1166  		if err != nil {
  1167  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1168  			os.Exit(2)
  1169  		}
  1170  		runtime.GC() // materialize all statistics
  1171  		if err = m.deps.WriteHeapProfile(f); err != nil {
  1172  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *memProfile, err)
  1173  			os.Exit(2)
  1174  		}
  1175  		f.Close()
  1176  	}
  1177  	if *blockProfile != "" && *blockProfileRate >= 0 {
  1178  		f, err := os.Create(toOutputDir(*blockProfile))
  1179  		if err != nil {
  1180  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1181  			os.Exit(2)
  1182  		}
  1183  		if err = m.deps.WriteProfileTo("block", f, 0); err != nil {
  1184  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *blockProfile, err)
  1185  			os.Exit(2)
  1186  		}
  1187  		f.Close()
  1188  	}
  1189  	if *mutexProfile != "" && *mutexProfileFraction >= 0 {
  1190  		f, err := os.Create(toOutputDir(*mutexProfile))
  1191  		if err != nil {
  1192  			fmt.Fprintf(os.Stderr, "testing: %s\n", err)
  1193  			os.Exit(2)
  1194  		}
  1195  		if err = m.deps.WriteProfileTo("mutex", f, 0); err != nil {
  1196  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s\n", *blockProfile, err)
  1197  			os.Exit(2)
  1198  		}
  1199  		f.Close()
  1200  	}
  1201  	if cover.Mode != "" {
  1202  		coverReport()
  1203  	}
  1204  }
  1205  
  1206  // toOutputDir returns the file name relocated, if required, to outputDir.
  1207  // Simple implementation to avoid pulling in path/filepath.
  1208  func toOutputDir(path string) string {
  1209  	if *outputDir == "" || path == "" {
  1210  		return path
  1211  	}
  1212  	if runtime.GOOS == "windows" {
  1213  		// On Windows, it's clumsy, but we can be almost always correct
  1214  		// by just looking for a drive letter and a colon.
  1215  		// Absolute paths always have a drive letter (ignoring UNC).
  1216  		// Problem: if path == "C:A" and outputdir == "C:\Go" it's unclear
  1217  		// what to do, but even then path/filepath doesn't help.
  1218  		// TODO: Worth doing better? Probably not, because we're here only
  1219  		// under the management of go test.
  1220  		if len(path) >= 2 {
  1221  			letter, colon := path[0], path[1]
  1222  			if ('a' <= letter && letter <= 'z' || 'A' <= letter && letter <= 'Z') && colon == ':' {
  1223  				// If path starts with a drive letter we're stuck with it regardless.
  1224  				return path
  1225  			}
  1226  		}
  1227  	}
  1228  	if os.IsPathSeparator(path[0]) {
  1229  		return path
  1230  	}
  1231  	return fmt.Sprintf("%s%c%s", *outputDir, os.PathSeparator, path)
  1232  }
  1233  
  1234  // startAlarm starts an alarm if requested.
  1235  func (m *M) startAlarm() {
  1236  	if *timeout > 0 {
  1237  		m.timer = time.AfterFunc(*timeout, func() {
  1238  			m.after()
  1239  			debug.SetTraceback("all")
  1240  			panic(fmt.Sprintf("test timed out after %v", *timeout))
  1241  		})
  1242  	}
  1243  }
  1244  
  1245  // stopAlarm turns off the alarm.
  1246  func (m *M) stopAlarm() {
  1247  	if *timeout > 0 {
  1248  		m.timer.Stop()
  1249  	}
  1250  }
  1251  
  1252  func parseCpuList() {
  1253  	for _, val := range strings.Split(*cpuListStr, ",") {
  1254  		val = strings.TrimSpace(val)
  1255  		if val == "" {
  1256  			continue
  1257  		}
  1258  		cpu, err := strconv.Atoi(val)
  1259  		if err != nil || cpu <= 0 {
  1260  			fmt.Fprintf(os.Stderr, "testing: invalid value %q for -test.cpu\n", val)
  1261  			os.Exit(1)
  1262  		}
  1263  		cpuList = append(cpuList, cpu)
  1264  	}
  1265  	if cpuList == nil {
  1266  		cpuList = append(cpuList, runtime.GOMAXPROCS(-1))
  1267  	}
  1268  }
  1269  
  1270  func shouldFailFast() bool {
  1271  	return *failFast && atomic.LoadUint32(&numFailed) > 0
  1272  }
  1273  

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