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Source file src/go/doc/testdata/testing.go

Documentation: go/doc/testdata

  // Copyright 2009 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Package testing provides support for automated testing of Go packages.
  // It is intended to be used in concert with the ``go test'' utility, which automates
  // execution of any function of the form
  //     func TestXxx(*testing.T)
  // where Xxx can be any alphanumeric string (but the first letter must not be in
  // [a-z]) and serves to identify the test routine.
  // These TestXxx routines should be declared within the package they are testing.
  //
  // Functions of the form
  //     func BenchmarkXxx(*testing.B)
  // are considered benchmarks, and are executed by go test when the -test.bench
  // flag is provided.
  //
  // A sample benchmark function looks like this:
  //     func BenchmarkHello(b *testing.B) {
  //         for i := 0; i < b.N; i++ {
  //             fmt.Sprintf("hello")
  //         }
  //     }
  // The benchmark package will vary b.N until the benchmark function lasts
  // long enough to be timed reliably. The output
  //     testing.BenchmarkHello    10000000    282 ns/op
  // means that the loop ran 10000000 times at a speed of 282 ns per loop.
  //
  // If a benchmark needs some expensive setup before running, the timer
  // may be stopped:
  //     func BenchmarkBigLen(b *testing.B) {
  //         b.StopTimer()
  //         big := NewBig()
  //         b.StartTimer()
  //         for i := 0; i < b.N; i++ {
  //             big.Len()
  //         }
  //     }
  package testing
  
  import (
  	"flag"
  	"fmt"
  	"os"
  	"runtime"
  	"runtime/pprof"
  	"strconv"
  	"strings"
  	"time"
  )
  
  var (
  	// The short flag requests that tests run more quickly, but its functionality
  	// is provided by test writers themselves. The testing package is just its
  	// home. The all.bash installation script sets it to make installation more
  	// efficient, but by default the flag is off so a plain "go test" will do a
  	// full test of the package.
  	short = flag.Bool("test.short", false, "run smaller test suite to save time")
  
  	// Report as tests are run; default is silent for success.
  	chatty         = flag.Bool("test.v", false, "verbose: print additional output")
  	match          = flag.String("test.run", "", "regular expression to select tests to run")
  	memProfile     = flag.String("test.memprofile", "", "write a memory profile to the named file after execution")
  	memProfileRate = flag.Int("test.memprofilerate", 0, "if >=0, sets runtime.MemProfileRate")
  	cpuProfile     = flag.String("test.cpuprofile", "", "write a cpu profile to the named file during execution")
  	timeout        = flag.Duration("test.timeout", 0, "if positive, sets an aggregate time limit for all tests")
  	cpuListStr     = flag.String("test.cpu", "", "comma-separated list of number of CPUs to use for each test")
  	parallel       = flag.Int("test.parallel", runtime.GOMAXPROCS(0), "maximum test parallelism")
  
  	cpuList []int
  )
  
  // common holds the elements common between T and B and
  // captures common methods such as Errorf.
  type common struct {
  	output   []byte    // Output generated by test or benchmark.
  	failed   bool      // Test or benchmark has failed.
  	start    time.Time // Time test or benchmark started
  	duration time.Duration
  	self     interface{}      // To be sent on signal channel when done.
  	signal   chan interface{} // Output for serial tests.
  }
  
  // Short reports whether the -test.short flag is set.
  func Short() bool {
  	return *short
  }
  
  // decorate inserts the final newline if needed and indentation tabs for formatting.
  // If addFileLine is true, it also prefixes the string with the file and line of the call site.
  func decorate(s string, addFileLine bool) string {
  	if addFileLine {
  		_, file, line, ok := runtime.Caller(3) // decorate + log + public function.
  		if ok {
  			// Truncate file name at last file name separator.
  			if index := strings.LastIndex(file, "/"); index >= 0 {
  				file = file[index+1:]
  			} else if index = strings.LastIndex(file, "\\"); index >= 0 {
  				file = file[index+1:]
  			}
  		} else {
  			file = "???"
  			line = 1
  		}
  		s = fmt.Sprintf("%s:%d: %s", file, line, s)
  	}
  	s = "\t" + s // Every line is indented at least one tab.
  	n := len(s)
  	if n > 0 && s[n-1] != '\n' {
  		s += "\n"
  		n++
  	}
  	for i := 0; i < n-1; i++ { // -1 to avoid final newline
  		if s[i] == '\n' {
  			// Second and subsequent lines are indented an extra tab.
  			return s[0:i+1] + "\t" + decorate(s[i+1:n], false)
  		}
  	}
  	return s
  }
  
  // T is a type passed to Test functions to manage test state and support formatted test logs.
  // Logs are accumulated during execution and dumped to standard error when done.
  type T struct {
  	common
  	name          string    // Name of test.
  	startParallel chan bool // Parallel tests will wait on this.
  }
  
  // Fail marks the function as having failed but continues execution.
  func (c *common) Fail() { c.failed = true }
  
  // Failed reports whether the function has failed.
  func (c *common) Failed() bool { return c.failed }
  
  // FailNow marks the function as having failed and stops its execution.
  // Execution will continue at the next Test.
  func (c *common) FailNow() {
  	c.Fail()
  
  	// Calling runtime.Goexit will exit the goroutine, which
  	// will run the deferred functions in this goroutine,
  	// which will eventually run the deferred lines in tRunner,
  	// which will signal to the test loop that this test is done.
  	//
  	// A previous version of this code said:
  	//
  	//	c.duration = ...
  	//	c.signal <- c.self
  	//	runtime.Goexit()
  	//
  	// This previous version duplicated code (those lines are in
  	// tRunner no matter what), but worse the goroutine teardown
  	// implicit in runtime.Goexit was not guaranteed to complete
  	// before the test exited. If a test deferred an important cleanup
  	// function (like removing temporary files), there was no guarantee
  	// it would run on a test failure. Because we send on c.signal during
  	// a top-of-stack deferred function now, we know that the send
  	// only happens after any other stacked defers have completed.
  	runtime.Goexit()
  }
  
  // log generates the output. It's always at the same stack depth.
  func (c *common) log(s string) {
  	c.output = append(c.output, decorate(s, true)...)
  }
  
  // Log formats its arguments using default formatting, analogous to Println(),
  // and records the text in the error log.
  func (c *common) Log(args ...interface{}) { c.log(fmt.Sprintln(args...)) }
  
  // Logf formats its arguments according to the format, analogous to Printf(),
  // and records the text in the error log.
  func (c *common) Logf(format string, args ...interface{}) { c.log(fmt.Sprintf(format, args...)) }
  
  // Error is equivalent to Log() followed by Fail().
  func (c *common) Error(args ...interface{}) {
  	c.log(fmt.Sprintln(args...))
  	c.Fail()
  }
  
  // Errorf is equivalent to Logf() followed by Fail().
  func (c *common) Errorf(format string, args ...interface{}) {
  	c.log(fmt.Sprintf(format, args...))
  	c.Fail()
  }
  
  // Fatal is equivalent to Log() followed by FailNow().
  func (c *common) Fatal(args ...interface{}) {
  	c.log(fmt.Sprintln(args...))
  	c.FailNow()
  }
  
  // Fatalf is equivalent to Logf() followed by FailNow().
  func (c *common) Fatalf(format string, args ...interface{}) {
  	c.log(fmt.Sprintf(format, args...))
  	c.FailNow()
  }
  
  // Parallel signals that this test is to be run in parallel with (and only with)
  // other parallel tests in this CPU group.
  func (t *T) Parallel() {
  	t.signal <- (*T)(nil) // Release main testing loop
  	<-t.startParallel     // Wait for serial tests to finish
  }
  
  // An internal type but exported because it is cross-package; part of the implementation
  // of go test.
  type InternalTest struct {
  	Name string
  	F    func(*T)
  }
  
  func tRunner(t *T, test *InternalTest) {
  	t.start = time.Now()
  
  	// When this goroutine is done, either because test.F(t)
  	// returned normally or because a test failure triggered
  	// a call to runtime.Goexit, record the duration and send
  	// a signal saying that the test is done.
  	defer func() {
  		t.duration = time.Now().Sub(t.start)
  		t.signal <- t
  	}()
  
  	test.F(t)
  }
  
  // An internal function but exported because it is cross-package; part of the implementation
  // of go test.
  func Main(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
  	flag.Parse()
  	parseCpuList()
  
  	before()
  	startAlarm()
  	testOk := RunTests(matchString, tests)
  	exampleOk := RunExamples(examples)
  	if !testOk || !exampleOk {
  		fmt.Println("FAIL")
  		os.Exit(1)
  	}
  	fmt.Println("PASS")
  	stopAlarm()
  	RunBenchmarks(matchString, benchmarks)
  	after()
  }
  
  func (t *T) report() {
  	tstr := fmt.Sprintf("(%.2f seconds)", t.duration.Seconds())
  	format := "--- %s: %s %s\n%s"
  	if t.failed {
  		fmt.Printf(format, "FAIL", t.name, tstr, t.output)
  	} else if *chatty {
  		fmt.Printf(format, "PASS", t.name, tstr, t.output)
  	}
  }
  
  func RunTests(matchString func(pat, str string) (bool, error), tests []InternalTest) (ok bool) {
  	ok = true
  	if len(tests) == 0 {
  		fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
  		return
  	}
  	for _, procs := range cpuList {
  		runtime.GOMAXPROCS(procs)
  		// We build a new channel tree for each run of the loop.
  		// collector merges in one channel all the upstream signals from parallel tests.
  		// If all tests pump to the same channel, a bug can occur where a test
  		// kicks off a goroutine that Fails, yet the test still delivers a completion signal,
  		// which skews the counting.
  		var collector = make(chan interface{})
  
  		numParallel := 0
  		startParallel := make(chan bool)
  
  		for i := 0; i < len(tests); i++ {
  			matched, err := matchString(*match, tests[i].Name)
  			if err != nil {
  				fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.run: %s\n", err)
  				os.Exit(1)
  			}
  			if !matched {
  				continue
  			}
  			testName := tests[i].Name
  			if procs != 1 {
  				testName = fmt.Sprintf("%s-%d", tests[i].Name, procs)
  			}
  			t := &T{
  				common: common{
  					signal: make(chan interface{}),
  				},
  				name:          testName,
  				startParallel: startParallel,
  			}
  			t.self = t
  			if *chatty {
  				fmt.Printf("=== RUN %s\n", t.name)
  			}
  			go tRunner(t, &tests[i])
  			out := (<-t.signal).(*T)
  			if out == nil { // Parallel run.
  				go func() {
  					collector <- <-t.signal
  				}()
  				numParallel++
  				continue
  			}
  			t.report()
  			ok = ok && !out.failed
  		}
  
  		running := 0
  		for numParallel+running > 0 {
  			if running < *parallel && numParallel > 0 {
  				startParallel <- true
  				running++
  				numParallel--
  				continue
  			}
  			t := (<-collector).(*T)
  			t.report()
  			ok = ok && !t.failed
  			running--
  		}
  	}
  	return
  }
  
  // before runs before all testing.
  func before() {
  	if *memProfileRate > 0 {
  		runtime.MemProfileRate = *memProfileRate
  	}
  	if *cpuProfile != "" {
  		f, err := os.Create(*cpuProfile)
  		if err != nil {
  			fmt.Fprintf(os.Stderr, "testing: %s", err)
  			return
  		}
  		if err := pprof.StartCPUProfile(f); err != nil {
  			fmt.Fprintf(os.Stderr, "testing: can't start cpu profile: %s", err)
  			f.Close()
  			return
  		}
  		// Could save f so after can call f.Close; not worth the effort.
  	}
  
  }
  
  // after runs after all testing.
  func after() {
  	if *cpuProfile != "" {
  		pprof.StopCPUProfile() // flushes profile to disk
  	}
  	if *memProfile != "" {
  		f, err := os.Create(*memProfile)
  		if err != nil {
  			fmt.Fprintf(os.Stderr, "testing: %s", err)
  			return
  		}
  		if err = pprof.WriteHeapProfile(f); err != nil {
  			fmt.Fprintf(os.Stderr, "testing: can't write %s: %s", *memProfile, err)
  		}
  		f.Close()
  	}
  }
  
  var timer *time.Timer
  
  // startAlarm starts an alarm if requested.
  func startAlarm() {
  	if *timeout > 0 {
  		timer = time.AfterFunc(*timeout, alarm)
  	}
  }
  
  // stopAlarm turns off the alarm.
  func stopAlarm() {
  	if *timeout > 0 {
  		timer.Stop()
  	}
  }
  
  // alarm is called if the timeout expires.
  func alarm() {
  	panic("test timed out")
  }
  
  func parseCpuList() {
  	if len(*cpuListStr) == 0 {
  		cpuList = append(cpuList, runtime.GOMAXPROCS(-1))
  	} else {
  		for _, val := range strings.Split(*cpuListStr, ",") {
  			cpu, err := strconv.Atoi(val)
  			if err != nil || cpu <= 0 {
  				fmt.Fprintf(os.Stderr, "testing: invalid value %q for -test.cpu", val)
  				os.Exit(1)
  			}
  			cpuList = append(cpuList, cpu)
  		}
  	}
  }
  

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