src/cmd/go/test.go - go - Git at Google

 // Copyright 2011 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 main

 import (
 	"bytes"
 	"fmt"
 	"go/ast"
 	"go/build"
 	"go/doc"
 	"go/parser"
 	"go/token"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"text/template"
 	"unicode"
 	"unicode/utf8"
 )

 // Break init loop.
 func init() {
 	cmdTest.Run = runTest
 }

 var cmdTest = &Command{
 	CustomFlags: true,
 	UsageLine:   "test [importpath...] [-file a.go -file b.go ...] [-c] [-x] [flags for test binary]",
 	Short:       "test packages",
 	Long: `
 'Go test' automates testing the packages named by the import paths.
 It prints a summary of the test results in the format:

 	test archive/tar
 	FAIL archive/zip
 	test compress/gzip
 	...

 followed by detailed output for each failed package.

 'Go test' recompiles each package along with any files with names matching
 the file pattern "*_test.go".  These additional files can contain test functions,
 benchmark functions, and example functions.  See 'go help testfunc' for more.

 By default, gotest needs no arguments.  It compiles and tests the package
 with source in the current directory, including tests, and runs the tests.
 If file names are given (with flag -file=test.go, one per extra test source file),
 only those test files are added to the package.  (The non-test files are always
 compiled.)

 The package is built in a temporary directory so it does not interfere with the
 non-test installation.

 See 'go help testflag' for details about flags
 handled by 'go test' and the test binary.

 See 'go help importpath' for more about import paths.

 See also: go build, go compile, go vet.
 	`,
 }

 var helpTestflag = &Command{
 	UsageLine: "testflag",
 	Short:     "description of testing flags",
 	Long: `
 The 'go test' command takes both flags that apply to 'go test' itself
 and flags that apply to the resulting test binary.

 The flags handled by 'go test' are:

 	-c  Compile the test binary to test.out but do not run it.

 	-file a.go
 	    Use only the tests in the source file a.go.
 	    Multiple -file flags may be provided.

 	-x  Print each subcommand gotest executes.

 The resulting test binary, called test.out, has its own flags:

 	-test.v
 	    Verbose output: log all tests as they are run.

 	-test.run pattern
 	    Run only those tests matching the regular expression.

 	-test.bench pattern
 	    Run benchmarks matching the regular expression.
 	    By default, no benchmarks run.

 	-test.cpuprofile cpu.out
 	    Write a CPU profile to the specified file before exiting.

 	-test.memprofile mem.out
 	    Write a memory profile to the specified file when all tests
 	    are complete.

 	-test.memprofilerate n
 	    Enable more precise (and expensive) memory profiles by setting
 	    runtime.MemProfileRate.  See 'godoc runtime MemProfileRate'.
 	    To profile all memory allocations, use -test.memprofilerate=1
 	    and set the environment variable GOGC=off to disable the
 	    garbage collector, provided the test can run in the available
 	    memory without garbage collection.

 	-test.parallel n
 	    Allow parallel execution of test functions that call t.Parallel.
 	    The value of this flag is the maximum number of tests to run
 	    simultaneously; by default, it is set to the value of GOMAXPROCS.

 	-test.short
 	    Tell long-running tests to shorten their run time.
 	    It is off by default but set during all.bash so that installing
 	    the Go tree can run a sanity check but not spend time running
 	    exhaustive tests.

 	-test.timeout n
 		If a test runs longer than n seconds, panic.

 	-test.benchtime n
 		Run enough iterations of each benchmark to take n seconds.
 		The default is 1 second.

 	-test.cpu 1,2,4
 	    Specify a list of GOMAXPROCS values for which the tests or
 	    benchmarks should be executed.  The default is the current value
 	    of GOMAXPROCS.

 For convenience, each of these -test.X flags of the test binary is
 also available as the flag -X in 'go test' itself.  Flags not listed
 here are passed through unaltered.  For instance, the command

 	go test -x -v -cpuprofile=prof.out -dir=testdata -update -file x_test.go

 will compile the test binary using x_test.go and then run it as

 	test.out -test.v -test.cpuprofile=prof.out -dir=testdata -update
 	`,
 }

 var helpTestfunc = &Command{
 	UsageLine: "testfunc",
 	Short:     "description of testing functions",
 	Long: `
 The 'go test' command expects to find test, benchmark, and example functions
 in the "*_test.go" files corresponding to the package under test.

 A test function is one named TestXXX (where XXX is any alphanumeric string
 not starting with a lower case letter) and should have the signature,

 	func TestXXX(t *testing.T) { ... }

 A benchmark function is one named BenchmarkXXX and should have the signature,

 	func BenchmarkXXX(b *testing.B) { ... }

 An example function is similar to a test function but, instead of using *testing.T
 to report success or failure, prints output to os.Stdout and os.Stderr.
 That output is compared against the function's doc comment.
 An example without a doc comment is compiled but not executed.

 Godoc displays the body of ExampleXXX to demonstrate the use
 of the function, constant, or variable XXX.  An example of a method M with
 receiver type T or *T is named ExampleT_M.  There may be multiple examples
 for a given function, constant, or variable, distinguished by a trailing _xxx,
 where xxx is a suffix not beginning with an upper case letter.

 Here is an example of an example:

 	// The output of this example function.
 	func ExamplePrintln() {
 		Println("The output of this example function.")
 	}

 See the documentation of the testing package for more information.
 		`,
 }

 // TODO(rsc): Rethink the flag handling.
 // It might be better to do
 //	go test [go-test-flags] [importpaths] [flags for test binary]
 // If there are no import paths then the two flag sections
 // run together, but we can deal with that.  Right now,
 //	go test -x  (ok)
 //	go test -x math (NOT OK)
 //	go test math -x (ok)
 // which is weird, because the -x really does apply to go test, not to math.
 // It is also possible that -file can go away.
 // For now just use the gotest code.

 var (
 	testC     bool     // -c flag
 	testX     bool     // -x flag
 	testFiles []string // -file flag(s)  TODO: not respected
 	testArgs  []string
 )

 func runTest(cmd *Command, args []string) {
 	// Determine which are the import paths
 	// (leading arguments not starting with -).
 	i := 0
 	for i < len(args) && !strings.HasPrefix(args[i], "-") {
 		i++
 	}
 	pkgs := packages(args[:i])
 	if len(pkgs) == 0 {
 		fatalf("no packages to test")
 	}

 	testArgs = testFlags(args[i:])
 	if testC && len(pkgs) != 1 {
 		fatalf("cannot use -c flag with multiple packages")
 	}

 	var b builder
 	b.init(false, false, testX)

 	var builds, runs []*action

 	// Prepare build + run actions for all packages being tested.
 	for _, p := range pkgs {
 		buildTest, runTest, err := b.test(p)
 		if err != nil {
 			errorf("%s: %s", p, err)
 			continue
 		}
 		builds = append(builds, buildTest)
 		runs = append(runs, runTest)
 	}

 	// Build+run the tests one at a time in the order
 	// specified on the command line.
 	// May want to revisit when we parallelize things,
 	// although probably not for benchmark runs.
 	for i, a := range builds {
 		if i > 0 {
 			// Make build of test i depend on
 			// completing the run of test i-1.
 			a.deps = append(a.deps, runs[i-1])
 		}
 	}

 	allRuns := &action{deps: runs}
 	b.do(allRuns)
 }

 func (b *builder) test(p *Package) (buildAction, runAction *action, err error) {
 	if len(p.info.TestGoFiles)+len(p.info.XTestGoFiles) == 0 {
 		build := &action{p: p}
 		run := &action{f: (*builder).notest, p: p, deps: []*action{build}}
 		return build, run, nil
 	}

 	// Build Package structs describing:
 	//	ptest - package + test files
 	//	pxtest - package of external test files
 	//	pmain - test.out binary
 	var ptest, pxtest, pmain *Package

 	// go/build does not distinguish the dependencies used
 	// by the TestGoFiles from the dependencies used by the
 	// XTestGoFiles, so we build one list and use it for both
 	// ptest and pxtest.  No harm done.
 	var imports []*Package
 	for _, path := range p.info.TestImports {
 		p1, err := loadPackage(path)
 		if err != nil {
 			return nil, nil, err
 		}
 		imports = append(imports, p1)
 	}

 	// The ptest package needs to be importable under the
 	// same import path that p has, but we cannot put it in
 	// the usual place in the temporary tree, because then
 	// other tests will see it as the real package.
 	// Instead we make a _test directory under the import path
 	// and then repeat the import path there.  We tell the
 	// compiler and linker to look in that _test directory first.
 	//
 	// That is, if the package under test is unicode/utf8,
 	// then the normal place to write the package archive is
 	// $WORK/unicode/utf8.a, but we write the test package archive to
 	// $WORK/unicode/utf8/_test/unicode/utf8.a.
 	// We write the external test package archive to
 	// $WORK/unicode/utf8/_test/unicode/utf8_test.a.
 	testDir := filepath.Join(b.work, filepath.FromSlash(p.ImportPath+"/_test"))
 	ptestObj := filepath.Join(testDir, filepath.FromSlash(p.ImportPath+".a"))
 	pxtestObj := filepath.Join(testDir, filepath.FromSlash(p.ImportPath+"_test.a"))

 	// Create the directory for the .a files.
 	ptestDir, _ := filepath.Split(ptestObj)
 	if err := b.mkdir(ptestDir); err != nil {
 		return nil, nil, err
 	}
 	if err := writeTestmain(filepath.Join(testDir, "_testmain.go"), p); err != nil {
 		return nil, nil, err
 	}

 	// Test package.
 	if len(p.info.TestGoFiles) > 0 {
 		ptest = new(Package)
 		*ptest = *p
 		ptest.GoFiles = nil
 		ptest.GoFiles = append(ptest.GoFiles, p.GoFiles...)
 		ptest.GoFiles = append(ptest.GoFiles, p.info.TestGoFiles...)
 		ptest.target = ""
 		ptest.Imports = append(append([]string{}, p.info.Imports...), p.info.TestImports...)
 		ptest.imports = append(append([]*Package{}, p.imports...), imports...)
 		ptest.pkgdir = testDir
 		a := b.action(modeBuild, modeBuild, ptest)
 		a.objdir = testDir + string(filepath.Separator)
 		a.objpkg = ptestObj
 		a.target = ptestObj
 		a.link = false
 	} else {
 		ptest = p
 	}

 	// External test package.
 	if len(p.info.XTestGoFiles) > 0 {
 		pxtest = &Package{
 			Name:       p.Name + "_test",
 			ImportPath: p.ImportPath + "_test",
 			Dir:        p.Dir,
 			GoFiles:    p.info.XTestGoFiles,
 			Imports:    p.info.TestImports,
 			t:          p.t,
 			info:       &build.DirInfo{},
 			imports:    imports,
 			pkgdir:     testDir,
 		}
 		pxtest.imports = append(pxtest.imports, ptest)
 		a := b.action(modeBuild, modeBuild, pxtest)
 		a.objdir = testDir + string(filepath.Separator)
 		a.objpkg = pxtestObj
 		a.target = pxtestObj
 	}

 	// Action for building test.out.
 	pmain = &Package{
 		Name:    "main",
 		Dir:     testDir,
 		GoFiles: []string{"_testmain.go"},
 		t:       p.t,
 		info:    &build.DirInfo{},
 		imports: []*Package{ptest},
 	}
 	if pxtest != nil {
 		pmain.imports = append(pmain.imports, pxtest)
 	}
 	a := b.action(modeBuild, modeBuild, pmain)
 	a.objdir = testDir + string(filepath.Separator)
 	a.objpkg = filepath.Join(testDir, "main.a")
 	a.target = filepath.Join(testDir, "test.out") + b.exe
 	pmainAction := a

 	if testC {
 		// -c flag: create action to copy binary to ./test.out.
 		runAction = &action{
 			f:      (*builder).install,
 			deps:   []*action{pmainAction},
 			p:      pmain,
 			target: "test.out" + b.exe,
 		}
 	} else {
 		// run test
 		runAction = &action{
 			f:          (*builder).runTest,
 			deps:       []*action{pmainAction},
 			p:          p,
 			ignoreFail: true,
 		}
 	}

 	return pmainAction, runAction, nil
 }

 var pass = []byte("\nPASS\n")

 // runTest is the action for running a test binary.
 func (b *builder) runTest(a *action) error {
 	args := []string{a.deps[0].target}
 	args = append(args, testArgs...)

 	if b.nflag || b.xflag {
 		b.showcmd("", "%s", strings.Join(args, " "))
 		if b.nflag {
 			return nil
 		}
 	}

 	if a.failed {
 		// We were unable to build the binary.
 		a.failed = false
 		fmt.Printf("FAIL\t%s [build failed]\n", a.p.ImportPath)
 		exitStatus = 1
 		return nil
 	}

 	cmd := exec.Command(args[0], args[1:]...)
 	cmd.Dir = a.p.Dir
 	out, err := cmd.CombinedOutput()
 	if err == nil && (bytes.Equal(out, pass[1:]) || bytes.HasSuffix(out, pass)) {
 		fmt.Printf("ok  \t%s\n", a.p.ImportPath)
 		return nil
 	}

 	fmt.Printf("FAIL\t%s\n", a.p.ImportPath)
 	exitStatus = 1
 	if len(out) > 0 {
 		os.Stdout.Write(out)
 		// assume printing the test binary's exit status is superfluous
 	} else {
 		fmt.Printf("%s\n", err)
 	}
 	return nil
 }

 // notest is the action for testing a package with no test files.
 func (b *builder) notest(a *action) error {
 	fmt.Printf("?   \t%s [no test files]\n", a.p.ImportPath)
 	return nil
 }

 // isTest tells whether name looks like a test (or benchmark, according to prefix).
 // It is a Test (say) if there is a character after Test that is not a lower-case letter.
 // We don't want TesticularCancer.
 func isTest(name, prefix string) bool {
 	if !strings.HasPrefix(name, prefix) {
 		return false
 	}
 	if len(name) == len(prefix) { // "Test" is ok
 		return true
 	}
 	rune, _ := utf8.DecodeRuneInString(name[len(prefix):])
 	return !unicode.IsLower(rune)
 }

 // writeTestmain writes the _testmain.go file for package p to
 // the file named out.
 func writeTestmain(out string, p *Package) error {
 	t := &testFuncs{
 		Package: p,
 		Info:    p.info,
 	}
 	for _, file := range p.info.TestGoFiles {
 		if err := t.load(filepath.Join(p.Dir, file), "_test", &t.NeedTest); err != nil {
 			return err
 		}
 	}
 	for _, file := range p.info.XTestGoFiles {
 		if err := t.load(filepath.Join(p.Dir, file), "_xtest", &t.NeedXtest); err != nil {
 			return err
 		}
 	}

 	f, err := os.Create(out)
 	if err != nil {
 		return err
 	}
 	defer f.Close()

 	if err := testmainTmpl.Execute(f, t); err != nil {
 		return err
 	}

 	return nil
 }

 type testFuncs struct {
 	Tests      []testFunc
 	Benchmarks []testFunc
 	Examples   []testFunc
 	Package    *Package
 	Info       *build.DirInfo
 	NeedTest   bool
 	NeedXtest  bool
 }

 type testFunc struct {
 	Package string // imported package name (_test or _xtest)
 	Name    string // function name
 	Output  string // output, for examples
 }

 var testFileSet = token.NewFileSet()

 func (t *testFuncs) load(filename, pkg string, seen *bool) error {
 	f, err := parser.ParseFile(testFileSet, filename, nil, parser.ParseComments)
 	if err != nil {
 		return err
 	}
 	for _, d := range f.Decls {
 		n, ok := d.(*ast.FuncDecl)
 		if !ok {
 			continue
 		}
 		if n.Recv != nil {
 			continue
 		}
 		name := n.Name.String()
 		switch {
 		case isTest(name, "Test"):
 			t.Tests = append(t.Tests, testFunc{pkg, name, ""})
 			*seen = true
 		case isTest(name, "Benchmark"):
 			t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, ""})
 			*seen = true
 		case isTest(name, "Example"):
 			output := doc.CommentText(n.Doc)
 			if output == "" {
 				// Don't run examples with no output.
 				continue
 			}
 			t.Examples = append(t.Examples, testFunc{pkg, name, output})
 			*seen = true
 		}
 	}

 	return nil
 }

 var testmainTmpl = template.Must(template.New("main").Parse(`
 package main

 import (
 	"regexp"
 	"testing"

 {{if .NeedTest}}
 	_test {{.Package.ImportPath | printf "%q"}}
 {{end}}
 {{if .NeedXtest}}
 	_xtest {{.Package.ImportPath | printf "%s_test" | printf "%q"}}
 {{end}}
 )

 var tests = []testing.InternalTest{
 {{range .Tests}}
 	{"{{.Name}}", {{.Package}}.{{.Name}}},
 {{end}}
 }

 var benchmarks = []testing.InternalBenchmark{
 {{range .Benchmarks}}
 	{"{{.Name}}", {{.Package}}.{{.Name}}},
 {{end}}
 }

 var examples = []testing.InternalExample{
 {{range .Examples}}
 	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}},
 {{end}}
 }

 var matchPat string
 var matchRe *regexp.Regexp

 func matchString(pat, str string) (result bool, err error) {
 	if matchRe == nil || matchPat != pat {
 		matchPat = pat
 		matchRe, err = regexp.Compile(matchPat)
 		if err != nil {
 			return
 		}
 	}
 	return matchRe.MatchString(str), nil
 }

 func main() {
 	testing.Main(matchString, tests, benchmarks, examples)
 }

 `))
	// Copyright 2011 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 main

	import (
	"bytes"
	"fmt"
	"go/ast"
	"go/build"
	"go/doc"
	"go/parser"
	"go/token"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"text/template"
	"unicode"
	"unicode/utf8"
	)

	// Break init loop.
	func init() {
	cmdTest.Run = runTest
	}

	var cmdTest = &Command{
	CustomFlags: true,
	UsageLine: "test [importpath...] [-file a.go -file b.go ...] [-c] [-x] [flags for test binary]",
	Short: "test packages",
	Long: `
	'Go test' automates testing the packages named by the import paths.
	It prints a summary of the test results in the format:

	test archive/tar
	FAIL archive/zip
	test compress/gzip
	...

	followed by detailed output for each failed package.

	'Go test' recompiles each package along with any files with names matching
	the file pattern "*_test.go". These additional files can contain test functions,
	benchmark functions, and example functions. See 'go help testfunc' for more.

	By default, gotest needs no arguments. It compiles and tests the package
	with source in the current directory, including tests, and runs the tests.
	If file names are given (with flag -file=test.go, one per extra test source file),
	only those test files are added to the package. (The non-test files are always
	compiled.)

	The package is built in a temporary directory so it does not interfere with the
	non-test installation.

	See 'go help testflag' for details about flags
	handled by 'go test' and the test binary.

	See 'go help importpath' for more about import paths.

	See also: go build, go compile, go vet.
	`,
	}

	var helpTestflag = &Command{
	UsageLine: "testflag",
	Short: "description of testing flags",
	Long: `
	The 'go test' command takes both flags that apply to 'go test' itself
	and flags that apply to the resulting test binary.

	The flags handled by 'go test' are:

	-c Compile the test binary to test.out but do not run it.

	-file a.go
	Use only the tests in the source file a.go.
	Multiple -file flags may be provided.

	-x Print each subcommand gotest executes.

	The resulting test binary, called test.out, has its own flags:

	-test.v
	Verbose output: log all tests as they are run.

	-test.run pattern
	Run only those tests matching the regular expression.

	-test.bench pattern
	Run benchmarks matching the regular expression.
	By default, no benchmarks run.

	-test.cpuprofile cpu.out
	Write a CPU profile to the specified file before exiting.

	-test.memprofile mem.out
	Write a memory profile to the specified file when all tests
	are complete.

	-test.memprofilerate n
	Enable more precise (and expensive) memory profiles by setting
	runtime.MemProfileRate. See 'godoc runtime MemProfileRate'.
	To profile all memory allocations, use -test.memprofilerate=1
	and set the environment variable GOGC=off to disable the
	garbage collector, provided the test can run in the available
	memory without garbage collection.

	-test.parallel n
	Allow parallel execution of test functions that call t.Parallel.
	The value of this flag is the maximum number of tests to run
	simultaneously; by default, it is set to the value of GOMAXPROCS.

	-test.short
	Tell long-running tests to shorten their run time.
	It is off by default but set during all.bash so that installing
	the Go tree can run a sanity check but not spend time running
	exhaustive tests.

	-test.timeout n
	If a test runs longer than n seconds, panic.

	-test.benchtime n
	Run enough iterations of each benchmark to take n seconds.
	The default is 1 second.

	-test.cpu 1,2,4
	Specify a list of GOMAXPROCS values for which the tests or
	benchmarks should be executed. The default is the current value
	of GOMAXPROCS.

	For convenience, each of these -test.X flags of the test binary is
	also available as the flag -X in 'go test' itself. Flags not listed
	here are passed through unaltered. For instance, the command

	go test -x -v -cpuprofile=prof.out -dir=testdata -update -file x_test.go

	will compile the test binary using x_test.go and then run it as

	test.out -test.v -test.cpuprofile=prof.out -dir=testdata -update
	`,
	}

	var helpTestfunc = &Command{
	UsageLine: "testfunc",
	Short: "description of testing functions",
	Long: `
	The 'go test' command expects to find test, benchmark, and example functions
	in the "*_test.go" files corresponding to the package under test.

	A test function is one named TestXXX (where XXX is any alphanumeric string
	not starting with a lower case letter) and should have the signature,

	func TestXXX(t *testing.T) { ... }

	A benchmark function is one named BenchmarkXXX and should have the signature,

	func BenchmarkXXX(b *testing.B) { ... }

	An example function is similar to a test function but, instead of using *testing.T
	to report success or failure, prints output to os.Stdout and os.Stderr.
	That output is compared against the function's doc comment.
	An example without a doc comment is compiled but not executed.

	Godoc displays the body of ExampleXXX to demonstrate the use
	of the function, constant, or variable XXX. An example of a method M with
	receiver type T or *T is named ExampleT_M. There may be multiple examples
	for a given function, constant, or variable, distinguished by a trailing _xxx,
	where xxx is a suffix not beginning with an upper case letter.

	Here is an example of an example:

	// The output of this example function.
	func ExamplePrintln() {
	Println("The output of this example function.")
	}

	See the documentation of the testing package for more information.
	`,
	}

	// TODO(rsc): Rethink the flag handling.
	// It might be better to do
	// go test [go-test-flags] [importpaths] [flags for test binary]
	// If there are no import paths then the two flag sections
	// run together, but we can deal with that. Right now,
	// go test -x (ok)
	// go test -x math (NOT OK)
	// go test math -x (ok)
	// which is weird, because the -x really does apply to go test, not to math.
	// It is also possible that -file can go away.
	// For now just use the gotest code.

	var (
	testC bool // -c flag
	testX bool // -x flag
	testFiles []string // -file flag(s) TODO: not respected
	testArgs []string
	)

	func runTest(cmd *Command, args []string) {
	// Determine which are the import paths
	// (leading arguments not starting with -).
	i := 0
	for i < len(args) && !strings.HasPrefix(args[i], "-") {
	i++
	}
	pkgs := packages(args[:i])
	if len(pkgs) == 0 {
	fatalf("no packages to test")
	}

	testArgs = testFlags(args[i:])
	if testC && len(pkgs) != 1 {
	fatalf("cannot use -c flag with multiple packages")
	}

	var b builder
	b.init(false, false, testX)

	var builds, runs []*action

	// Prepare build + run actions for all packages being tested.
	for _, p := range pkgs {
	buildTest, runTest, err := b.test(p)
	if err != nil {
	errorf("%s: %s", p, err)
	continue
	}
	builds = append(builds, buildTest)
	runs = append(runs, runTest)
	}

	// Build+run the tests one at a time in the order
	// specified on the command line.
	// May want to revisit when we parallelize things,
	// although probably not for benchmark runs.
	for i, a := range builds {
	if i > 0 {
	// Make build of test i depend on
	// completing the run of test i-1.
	a.deps = append(a.deps, runs[i-1])
	}
	}

	allRuns := &action{deps: runs}
	b.do(allRuns)
	}

	func (b builder) test(p Package) (buildAction, runAction *action, err error) {
	if len(p.info.TestGoFiles)+len(p.info.XTestGoFiles) == 0 {
	build := &action{p: p}
	run := &action{f: (builder).notest, p: p, deps: []action{build}}
	return build, run, nil
	}

	// Build Package structs describing:
	// ptest - package + test files
	// pxtest - package of external test files
	// pmain - test.out binary
	var ptest, pxtest, pmain *Package

	// go/build does not distinguish the dependencies used
	// by the TestGoFiles from the dependencies used by the
	// XTestGoFiles, so we build one list and use it for both
	// ptest and pxtest. No harm done.
	var imports []*Package
	for _, path := range p.info.TestImports {
	p1, err := loadPackage(path)
	if err != nil {
	return nil, nil, err
	}
	imports = append(imports, p1)
	}

	// The ptest package needs to be importable under the
	// same import path that p has, but we cannot put it in
	// the usual place in the temporary tree, because then
	// other tests will see it as the real package.
	// Instead we make a _test directory under the import path
	// and then repeat the import path there. We tell the
	// compiler and linker to look in that _test directory first.
	//
	// That is, if the package under test is unicode/utf8,
	// then the normal place to write the package archive is
	// $WORK/unicode/utf8.a, but we write the test package archive to
	// $WORK/unicode/utf8/_test/unicode/utf8.a.
	// We write the external test package archive to
	// $WORK/unicode/utf8/_test/unicode/utf8_test.a.
	testDir := filepath.Join(b.work, filepath.FromSlash(p.ImportPath+"/_test"))
	ptestObj := filepath.Join(testDir, filepath.FromSlash(p.ImportPath+".a"))
	pxtestObj := filepath.Join(testDir, filepath.FromSlash(p.ImportPath+"_test.a"))

	// Create the directory for the .a files.
	ptestDir, _ := filepath.Split(ptestObj)
	if err := b.mkdir(ptestDir); err != nil {
	return nil, nil, err
	}
	if err := writeTestmain(filepath.Join(testDir, "_testmain.go"), p); err != nil {
	return nil, nil, err
	}

	// Test package.
	if len(p.info.TestGoFiles) > 0 {
	ptest = new(Package)
	ptest = p
	ptest.GoFiles = nil
	ptest.GoFiles = append(ptest.GoFiles, p.GoFiles...)
	ptest.GoFiles = append(ptest.GoFiles, p.info.TestGoFiles...)
	ptest.target = ""
	ptest.Imports = append(append([]string{}, p.info.Imports...), p.info.TestImports...)
	ptest.imports = append(append([]*Package{}, p.imports...), imports...)
	ptest.pkgdir = testDir
	a := b.action(modeBuild, modeBuild, ptest)
	a.objdir = testDir + string(filepath.Separator)
	a.objpkg = ptestObj
	a.target = ptestObj
	a.link = false
	} else {
	ptest = p
	}

	// External test package.
	if len(p.info.XTestGoFiles) > 0 {
	pxtest = &Package{
	Name: p.Name + "_test",
	ImportPath: p.ImportPath + "_test",
	Dir: p.Dir,
	GoFiles: p.info.XTestGoFiles,
	Imports: p.info.TestImports,
	t: p.t,
	info: &build.DirInfo{},
	imports: imports,
	pkgdir: testDir,
	}
	pxtest.imports = append(pxtest.imports, ptest)
	a := b.action(modeBuild, modeBuild, pxtest)
	a.objdir = testDir + string(filepath.Separator)
	a.objpkg = pxtestObj
	a.target = pxtestObj
	}

	// Action for building test.out.
	pmain = &Package{
	Name: "main",
	Dir: testDir,
	GoFiles: []string{"_testmain.go"},
	t: p.t,
	info: &build.DirInfo{},
	imports: []*Package{ptest},
	}
	if pxtest != nil {
	pmain.imports = append(pmain.imports, pxtest)
	}
	a := b.action(modeBuild, modeBuild, pmain)
	a.objdir = testDir + string(filepath.Separator)
	a.objpkg = filepath.Join(testDir, "main.a")
	a.target = filepath.Join(testDir, "test.out") + b.exe
	pmainAction := a

	if testC {
	// -c flag: create action to copy binary to ./test.out.
	runAction = &action{
	f: (*builder).install,
	deps: []*action{pmainAction},
	p: pmain,
	target: "test.out" + b.exe,
	}
	} else {
	// run test
	runAction = &action{
	f: (*builder).runTest,
	deps: []*action{pmainAction},
	p: p,
	ignoreFail: true,
	}
	}

	return pmainAction, runAction, nil
	}

	var pass = []byte("\nPASS\n")

	// runTest is the action for running a test binary.
	func (b builder) runTest(a action) error {
	args := []string{a.deps[0].target}
	args = append(args, testArgs...)

	if b.nflag \|\| b.xflag {
	b.showcmd("", "%s", strings.Join(args, " "))
	if b.nflag {
	return nil
	}
	}

	if a.failed {
	// We were unable to build the binary.
	a.failed = false
	fmt.Printf("FAIL\t%s [build failed]\n", a.p.ImportPath)
	exitStatus = 1
	return nil
	}

	cmd := exec.Command(args[0], args[1:]...)
	cmd.Dir = a.p.Dir
	out, err := cmd.CombinedOutput()
	if err == nil && (bytes.Equal(out, pass[1:]) \|\| bytes.HasSuffix(out, pass)) {
	fmt.Printf("ok \t%s\n", a.p.ImportPath)
	return nil
	}

	fmt.Printf("FAIL\t%s\n", a.p.ImportPath)
	exitStatus = 1
	if len(out) > 0 {
	os.Stdout.Write(out)
	// assume printing the test binary's exit status is superfluous
	} else {
	fmt.Printf("%s\n", err)
	}
	return nil
	}

	// notest is the action for testing a package with no test files.
	func (b builder) notest(a action) error {
	fmt.Printf("? \t%s [no test files]\n", a.p.ImportPath)
	return nil
	}

	// isTest tells whether name looks like a test (or benchmark, according to prefix).
	// It is a Test (say) if there is a character after Test that is not a lower-case letter.
	// We don't want TesticularCancer.
	func isTest(name, prefix string) bool {
	if !strings.HasPrefix(name, prefix) {
	return false
	}
	if len(name) == len(prefix) { // "Test" is ok
	return true
	}
	rune, _ := utf8.DecodeRuneInString(name[len(prefix):])
	return !unicode.IsLower(rune)
	}

	// writeTestmain writes the _testmain.go file for package p to
	// the file named out.
	func writeTestmain(out string, p *Package) error {
	t := &testFuncs{
	Package: p,
	Info: p.info,
	}
	for _, file := range p.info.TestGoFiles {
	if err := t.load(filepath.Join(p.Dir, file), "_test", &t.NeedTest); err != nil {
	return err
	}
	}
	for _, file := range p.info.XTestGoFiles {
	if err := t.load(filepath.Join(p.Dir, file), "_xtest", &t.NeedXtest); err != nil {
	return err
	}
	}

	f, err := os.Create(out)
	if err != nil {
	return err
	}
	defer f.Close()

	if err := testmainTmpl.Execute(f, t); err != nil {
	return err
	}

	return nil
	}

	type testFuncs struct {
	Tests []testFunc
	Benchmarks []testFunc
	Examples []testFunc
	Package *Package
	Info *build.DirInfo
	NeedTest bool
	NeedXtest bool
	}

	type testFunc struct {
	Package string // imported package name (_test or _xtest)
	Name string // function name
	Output string // output, for examples
	}

	var testFileSet = token.NewFileSet()

	func (t testFuncs) load(filename, pkg string, seen bool) error {
	f, err := parser.ParseFile(testFileSet, filename, nil, parser.ParseComments)
	if err != nil {
	return err
	}
	for _, d := range f.Decls {
	n, ok := d.(*ast.FuncDecl)
	if !ok {
	continue
	}
	if n.Recv != nil {
	continue
	}
	name := n.Name.String()
	switch {
	case isTest(name, "Test"):
	t.Tests = append(t.Tests, testFunc{pkg, name, ""})
	*seen = true
	case isTest(name, "Benchmark"):
	t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, ""})
	*seen = true
	case isTest(name, "Example"):
	output := doc.CommentText(n.Doc)
	if output == "" {
	// Don't run examples with no output.
	continue
	}
	t.Examples = append(t.Examples, testFunc{pkg, name, output})
	*seen = true
	}
	}

	return nil
	}

	var testmainTmpl = template.Must(template.New("main").Parse(`
	package main

	import (
	"regexp"
	"testing"

	{{if .NeedTest}}
	_test {{.Package.ImportPath \| printf "%q"}}
	{{end}}
	{{if .NeedXtest}}
	_xtest {{.Package.ImportPath \| printf "%s_test" \| printf "%q"}}
	{{end}}
	)

	var tests = []testing.InternalTest{
	{{range .Tests}}
	{"{{.Name}}", {{.Package}}.{{.Name}}},
	{{end}}
	}

	var benchmarks = []testing.InternalBenchmark{
	{{range .Benchmarks}}
	{"{{.Name}}", {{.Package}}.{{.Name}}},
	{{end}}
	}

	var examples = []testing.InternalExample{
	{{range .Examples}}
	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output \| printf "%q"}}},
	{{end}}
	}

	var matchPat string
	var matchRe *regexp.Regexp

	func matchString(pat, str string) (result bool, err error) {
	if matchRe == nil \|\| matchPat != pat {
	matchPat = pat
	matchRe, err = regexp.Compile(matchPat)
	if err != nil {
	return
	}
	}
	return matchRe.MatchString(str), nil
	}

	func main() {
	testing.Main(matchString, tests, benchmarks, examples)
	}

	`))