func (node *MatrixSelector) String() string {
	vecSelector := &VectorSelector{
		Name:          node.Name,
		LabelMatchers: node.LabelMatchers,
	}
	offset := ""
	if node.Offset != time.Duration(0) {
		offset = fmt.Sprintf(" OFFSET %s", model.Duration(node.Offset))
	}
	return fmt.Sprintf("%s[%s]%s", vecSelector.String(), model.Duration(node.Range), offset)
}

func TestNewHTTPCACert(t *testing.T) {
	server := httptest.NewUnstartedServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				w.Header().Set("Content-Type", `text/plain; version=0.0.4`)
				w.Write([]byte{})
			},
		),
	)
	server.TLS = newTLSConfig(t)
	server.StartTLS()
	defer server.Close()

	cfg := &config.ScrapeConfig{
		ScrapeTimeout: model.Duration(1 * time.Second),
		TLSConfig: config.TLSConfig{
			CAFile: "testdata/ca.cer",
		},
	}
	c, err := newHTTPClient(cfg)
	if err != nil {
		t.Fatal(err)
	}
	_, err = c.Get(server.URL)
	if err != nil {
		t.Fatal(err)
	}
}

func TestMarathonSDRunAndStop(t *testing.T) {
	var (
		refreshInterval = model.Duration(time.Millisecond * 10)
		conf            = config.MarathonSDConfig{Servers: testServers, RefreshInterval: refreshInterval}
		ch              = make(chan []*config.TargetGroup)
	)
	md, err := NewDiscovery(&conf)
	if err != nil {
		t.Fatalf("%s", err)
	}
	md.appsClient = func(client *http.Client, url string) (*AppList, error) {
		return marathonTestAppList(marathonValidLabel, 1), nil
	}
	ctx, cancel := context.WithCancel(context.Background())

	go func() {
		for {
			select {
			case _, ok := <-ch:
				if !ok {
					return
				}
				cancel()
			case <-time.After(md.refreshInterval * 3):
				cancel()
				t.Fatalf("Update took too long.")
			}
		}
	}()

	md.Run(ctx, ch)
}

func TestNewHTTPBasicAuth(t *testing.T) {
	server := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				username, password, ok := r.BasicAuth()
				if !(ok && username == "user" && password == "password123") {
					t.Fatalf("Basic authorization header was not set correctly: expected '%v:%v', got '%v:%v'", "user", "password123", username, password)
				}
			},
		),
	)
	defer server.Close()

	cfg := &config.ScrapeConfig{
		ScrapeTimeout: model.Duration(1 * time.Second),
		BasicAuth: &config.BasicAuth{
			Username: "user",
			Password: "password123",
		},
	}
	c, err := newHTTPClient(cfg)
	if err != nil {
		t.Fatal(err)
	}
	_, err = c.Get(server.URL)
	if err != nil {
		t.Fatal(err)
	}
}

func TestNewHTTPWithBadServerName(t *testing.T) {
	server := httptest.NewUnstartedServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				w.Header().Set("Content-Type", `text/plain; version=0.0.4`)
				w.Write([]byte{})
			},
		),
	)
	server.TLS = newTLSConfig("servername", t)
	server.StartTLS()
	defer server.Close()

	cfg := &config.ScrapeConfig{
		ScrapeTimeout: model.Duration(1 * time.Second),
		TLSConfig: config.TLSConfig{
			CAFile:     caCertPath,
			ServerName: "badname",
		},
	}
	c, err := NewHTTPClient(cfg)
	if err != nil {
		t.Fatal(err)
	}
	_, err = c.Get(server.URL)
	if err == nil {
		t.Fatal("Expected error, got nil.")
	}
}

func newTestTarget(targetURL string, deadline time.Duration, baseLabels model.LabelSet) *Target {
	cfg := &config.ScrapeConfig{
		ScrapeTimeout: model.Duration(deadline),
	}
	c, _ := newHTTPClient(cfg)
	t := &Target{
		url: &url.URL{
			Scheme: "http",
			Host:   strings.TrimLeft(targetURL, "http://"),
			Path:   "/metrics",
		},
		status:          &TargetStatus{},
		scrapeInterval:  1 * time.Millisecond,
		httpClient:      c,
		scraperStopping: make(chan struct{}),
		scraperStopped:  make(chan struct{}),
	}
	t.baseLabels = model.LabelSet{
		model.InstanceLabel: model.LabelValue(t.InstanceIdentifier()),
	}
	for baseLabel, baseValue := range baseLabels {
		t.baseLabels[baseLabel] = baseValue
	}
	return t
}

func TestNewHTTPBearerTokenFile(t *testing.T) {
	server := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				expected := "Bearer 12345"
				received := r.Header.Get("Authorization")
				if expected != received {
					t.Fatalf("Authorization header was not set correctly: expected '%v', got '%v'", expected, received)
				}
			},
		),
	)
	defer server.Close()

	cfg := &config.ScrapeConfig{
		ScrapeTimeout:   model.Duration(1 * time.Second),
		BearerTokenFile: "testdata/bearertoken.txt",
	}
	c, err := newHTTPClient(cfg)
	if err != nil {
		t.Fatal(err)
	}
	_, err = c.Get(server.URL)
	if err != nil {
		t.Fatal(err)
	}
}

func TestNewHTTPClientCert(t *testing.T) {
	server := httptest.NewUnstartedServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				w.Header().Set("Content-Type", `text/plain; version=0.0.4`)
				w.Write([]byte{})
			},
		),
	)
	tlsConfig := newTLSConfig(t)
	tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert
	tlsConfig.ClientCAs = tlsConfig.RootCAs
	tlsConfig.BuildNameToCertificate()
	server.TLS = tlsConfig
	server.StartTLS()
	defer server.Close()

	cfg := &config.ScrapeConfig{
		ScrapeTimeout: model.Duration(1 * time.Second),
		TLSConfig: config.TLSConfig{
			CAFile:   "testdata/ca.cer",
			CertFile: "testdata/client.cer",
			KeyFile:  "testdata/client.key",
		},
	}
	c, err := newHTTPClient(cfg)
	if err != nil {
		t.Fatal(err)
	}
	_, err = c.Get(server.URL)
	if err != nil {
		t.Fatal(err)
	}
}

func TestURLParams(t *testing.T) {
	server := httptest.NewServer(
		http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				w.Header().Set("Content-Type", `text/plain; version=0.0.4`)
				w.Write([]byte{})
				r.ParseForm()
				if r.Form["foo"][0] != "bar" {
					t.Fatalf("URL parameter 'foo' had unexpected first value '%v'", r.Form["foo"][0])
				}
				if r.Form["foo"][1] != "baz" {
					t.Fatalf("URL parameter 'foo' had unexpected second value '%v'", r.Form["foo"][1])
				}
			},
		),
	)
	defer server.Close()
	serverURL, err := url.Parse(server.URL)
	if err != nil {
		t.Fatal(err)
	}

	target, err := NewTarget(
		&config.ScrapeConfig{
			JobName:        "test_job1",
			ScrapeInterval: model.Duration(1 * time.Minute),
			ScrapeTimeout:  model.Duration(1 * time.Second),
			Scheme:         serverURL.Scheme,
			Params: url.Values{
				"foo": []string{"bar", "baz"},
			},
		},
		model.LabelSet{
			model.SchemeLabel:  model.LabelValue(serverURL.Scheme),
			model.AddressLabel: model.LabelValue(serverURL.Host),
			"__param_foo":      "bar",
		},
		nil,
	)
	if err != nil {
		t.Fatal(err)
	}
	app := &collectResultAppender{}
	if err = target.scrape(app); err != nil {
		t.Fatal(err)
	}
}

func (r *AlertingRule) String() string {
	s := fmt.Sprintf("ALERT %s", r.name)
	s += fmt.Sprintf("\n\tIF %s", r.vector)
	if r.holdDuration > 0 {
		s += fmt.Sprintf("\n\tFOR %s", model.Duration(r.holdDuration))
	}
	if len(r.labels) > 0 {
		s += fmt.Sprintf("\n\tLABELS %s", r.labels)
	}
	if len(r.annotations) > 0 {
		s += fmt.Sprintf("\n\tANNOTATIONS %s", r.annotations)
	}
	return s
}

func TestNewTargetWithBadTLSConfig(t *testing.T) {
	cfg := &config.ScrapeConfig{
		ScrapeTimeout: model.Duration(1 * time.Second),
		TLSConfig: config.TLSConfig{
			CAFile:   "testdata/nonexistent_ca.cer",
			CertFile: "testdata/nonexistent_client.cer",
			KeyFile:  "testdata/nonexistent_client.key",
		},
	}
	_, err := NewTarget(cfg, nil, nil)
	if err == nil {
		t.Fatalf("Expected error, got nil.")
	}
}

func newTestTarget(targetURL string, deadline time.Duration, labels model.LabelSet) *Target {
	labels = labels.Clone()
	labels[model.SchemeLabel] = "http"
	labels[model.AddressLabel] = model.LabelValue(strings.TrimLeft(targetURL, "http://"))
	labels[model.MetricsPathLabel] = "/metrics"

	t := &Target{
		scrapeConfig: &config.ScrapeConfig{
			ScrapeInterval: model.Duration(time.Millisecond),
			ScrapeTimeout:  model.Duration(deadline),
		},
		labels:          labels,
		status:          &TargetStatus{},
		scraperStopping: make(chan struct{}),
		scraperStopped:  make(chan struct{}),
	}

	var err error
	if t.httpClient, err = t.client(); err != nil {
		panic(err)
	}

	return t
}

// HTMLSnippet returns an HTML snippet representing this alerting rule. The
// resulting snippet is expected to be presented in a <pre> element, so that
// line breaks and other returned whitespace is respected.
func (r *AlertingRule) HTMLSnippet(pathPrefix string) html_template.HTML {
	alertMetric := model.Metric{
		model.MetricNameLabel: alertMetricName,
		alertNameLabel:        model.LabelValue(r.name),
	}
	s := fmt.Sprintf("ALERT <a href=%q>%s</a>", pathPrefix+strutil.GraphLinkForExpression(alertMetric.String()), r.name)
	s += fmt.Sprintf("\n  IF <a href=%q>%s</a>", pathPrefix+strutil.GraphLinkForExpression(r.vector.String()), r.vector)
	if r.holdDuration > 0 {
		s += fmt.Sprintf("\n  FOR %s", model.Duration(r.holdDuration))
	}
	if len(r.labels) > 0 {
		s += fmt.Sprintf("\n  LABELS %s", r.labels)
	}
	if len(r.annotations) > 0 {
		s += fmt.Sprintf("\n  ANNOTATIONS %s", r.annotations)
	}
	return html_template.HTML(s)
}

		return nil, err
	}
	resolveFilepaths(filepath.Dir(filename), cfg)
	return cfg, nil
}

// The defaults applied before parsing the respective config sections.
var (
	// DefaultConfig is the default top-level configuration.
	DefaultConfig = Config{
		GlobalConfig: DefaultGlobalConfig,
	}

	// DefaultGlobalConfig is the default global configuration.
	DefaultGlobalConfig = GlobalConfig{
		ScrapeInterval:     model.Duration(1 * time.Minute),
		ScrapeTimeout:      model.Duration(10 * time.Second),
		EvaluationInterval: model.Duration(1 * time.Minute),
	}

	// DefaultScrapeConfig is the default scrape configuration.
	DefaultScrapeConfig = ScrapeConfig{
		// ScrapeTimeout and ScrapeInterval default to the
		// configured globals.
		MetricsPath: "/metrics",
		Scheme:      "http",
		HonorLabels: false,
	}

	// DefaultRelabelConfig is the default Relabel configuration.
	DefaultRelabelConfig = RelabelConfig{

func TestTargetManagerConfigUpdate(t *testing.T) {
	testJob1 := &config.ScrapeConfig{
		JobName:        "test_job1",
		ScrapeInterval: model.Duration(1 * time.Minute),
		Params: url.Values{
			"testParam": []string{"paramValue", "secondValue"},
		},
		TargetGroups: []*config.TargetGroup{{
			Targets: []model.LabelSet{
				{model.AddressLabel: "example.org:80"},
				{model.AddressLabel: "example.com"},
			},
		}},
		RelabelConfigs: []*config.RelabelConfig{
			{
				// Copy out the URL parameter.
				SourceLabels: model.LabelNames{"__param_testParam"},
				Regex:        config.MustNewRegexp("(.*)"),
				TargetLabel:  "testParam",
				Replacement:  "$1",
				Action:       config.RelabelReplace,
			},
			{
				// The port number is added after relabeling, so
				// this relabel rule should have no effect.
				SourceLabels: model.LabelNames{model.AddressLabel},
				Regex:        config.MustNewRegexp("example.com:80"),
				Action:       config.RelabelDrop,
			},
		},
	}
	testJob2 := &config.ScrapeConfig{
		JobName:        "test_job2",
		ScrapeInterval: model.Duration(1 * time.Minute),
		TargetGroups: []*config.TargetGroup{
			{
				Targets: []model.LabelSet{
					{model.AddressLabel: "example.org:8080"},
					{model.AddressLabel: "example.com:8081"},
				},
				Labels: model.LabelSet{
					"foo":  "bar",
					"boom": "box",
				},
			},
			{
				Targets: []model.LabelSet{
					{model.AddressLabel: "test.com:1234"},
				},
			},
			{
				Targets: []model.LabelSet{
					{model.AddressLabel: "test.com:1235"},
				},
				Labels: model.LabelSet{"instance": "fixed"},
			},
		},
		RelabelConfigs: []*config.RelabelConfig{
			{
				SourceLabels: model.LabelNames{model.AddressLabel},
				Regex:        config.MustNewRegexp(`test\.(.*?):(.*)`),
				Replacement:  "foo.${1}:${2}",
				TargetLabel:  model.AddressLabel,
				Action:       config.RelabelReplace,
			},
			{
				// Add a new label for example.* targets.
				SourceLabels: model.LabelNames{model.AddressLabel, "boom", "foo"},
				Regex:        config.MustNewRegexp("example.*?-b([a-z-]+)r"),
				TargetLabel:  "new",
				Replacement:  "$1",
				Separator:    "-",
				Action:       config.RelabelReplace,
			},
			{
				// Drop an existing label.
				SourceLabels: model.LabelNames{"boom"},
				Regex:        config.MustNewRegexp(".*"),
				TargetLabel:  "boom",
				Replacement:  "",
				Action:       config.RelabelReplace,
			},
		},
	}
	// Test that targets without host:port addresses are dropped.
	testJob3 := &config.ScrapeConfig{
		JobName:        "test_job1",
		ScrapeInterval: model.Duration(1 * time.Minute),
		TargetGroups: []*config.TargetGroup{{
			Targets: []model.LabelSet{
				{model.AddressLabel: "example.net:80"},
			},
		}},
		RelabelConfigs: []*config.RelabelConfig{
			{
				SourceLabels: model.LabelNames{model.AddressLabel},
				Regex:        config.MustNewRegexp("(.*)"),
				TargetLabel:  "__address__",
				Replacement:  "http://$1",
				Action:       config.RelabelReplace,
//.........这里部分代码省略.........

import (
	"encoding/json"
	"io/ioutil"
	"net/url"
	"reflect"
	"strings"
	"testing"
	"time"

	"github.com/prometheus/common/model"
	"gopkg.in/yaml.v2"
)

var expectedConf = &Config{
	GlobalConfig: GlobalConfig{
		ScrapeInterval:     model.Duration(15 * time.Second),
		ScrapeTimeout:      DefaultGlobalConfig.ScrapeTimeout,
		EvaluationInterval: model.Duration(30 * time.Second),

		ExternalLabels: model.LabelSet{
			"monitor": "codelab",
			"foo":     "bar",
		},
	},

	RuleFiles: []string{
		"testdata/first.rules",
		"/absolute/second.rules",
		"testdata/my/*.rules",
	},

func TestTargetManagerChan(t *testing.T) {
	testJob1 := &config.ScrapeConfig{
		JobName:        "test_job1",
		ScrapeInterval: model.Duration(1 * time.Minute),
		TargetGroups: []*config.TargetGroup{{
			Targets: []model.LabelSet{
				{model.AddressLabel: "example.org:80"},
				{model.AddressLabel: "example.com:80"},
			},
		}},
	}
	prov1 := &fakeTargetProvider{
		sources: []string{"src1", "src2"},
		update:  make(chan *config.TargetGroup),
	}

	targetManager := &TargetManager{
		sampleAppender: nopAppender{},
		providers: map[*config.ScrapeConfig][]TargetProvider{
			testJob1: {prov1},
		},
		targets: make(map[string][]*Target),
	}
	go targetManager.Run()
	defer targetManager.Stop()

	sequence := []struct {
		tgroup   *config.TargetGroup
		expected map[string][]model.LabelSet
	}{
		{
			tgroup: &config.TargetGroup{
				Source: "src1",
				Targets: []model.LabelSet{
					{model.AddressLabel: "test-1:1234"},
					{model.AddressLabel: "test-2:1234", "label": "set"},
					{model.AddressLabel: "test-3:1234"},
				},
			},
			expected: map[string][]model.LabelSet{
				"src1": {
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-1:1234"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-2:1234", "label": "set"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-3:1234"},
				},
			},
		}, {
			tgroup: &config.TargetGroup{
				Source: "src2",
				Targets: []model.LabelSet{
					{model.AddressLabel: "test-1:1235"},
					{model.AddressLabel: "test-2:1235"},
					{model.AddressLabel: "test-3:1235"},
				},
				Labels: model.LabelSet{"group": "label"},
			},
			expected: map[string][]model.LabelSet{
				"src1": {
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-1:1234"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-2:1234", "label": "set"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-3:1234"},
				},
				"src2": {
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-1:1235", "group": "label"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-2:1235", "group": "label"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-3:1235", "group": "label"},
				},
			},
		}, {
			tgroup: &config.TargetGroup{
				Source:  "src2",
				Targets: []model.LabelSet{},
			},
			expected: map[string][]model.LabelSet{
				"src1": {
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-1:1234"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-2:1234", "label": "set"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-3:1234"},
				},
			},
		}, {
			tgroup: &config.TargetGroup{
				Source: "src1",
				Targets: []model.LabelSet{
					{model.AddressLabel: "test-1:1234", "added": "label"},
					{model.AddressLabel: "test-3:1234"},
					{model.AddressLabel: "test-4:1234", "fancy": "label"},
				},
			},
			expected: map[string][]model.LabelSet{
				"src1": {
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-1:1234", "added": "label"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-3:1234"},
					{model.JobLabel: "test_job1", model.InstanceLabel: "test-4:1234", "fancy": "label"},
				},
			},
		},
	}

	for i, step := range sequence {
//.........这里部分代码省略.........

func TestScrapePoolReload(t *testing.T) {
	var mtx sync.Mutex
	numTargets := 20

	stopped := map[uint64]bool{}

	reloadCfg := &config.ScrapeConfig{
		ScrapeInterval: model.Duration(3 * time.Second),
		ScrapeTimeout:  model.Duration(2 * time.Second),
	}
	// On starting to run, new loops created on reload check whether their preceeding
	// equivalents have been stopped.
	newLoop := func(ctx context.Context, s scraper, app, reportApp storage.SampleAppender) loop {
		l := &testLoop{}
		l.startFunc = func(interval, timeout time.Duration, errc chan<- error) {
			if interval != 3*time.Second {
				t.Errorf("Expected scrape interval %d but got %d", 3*time.Second, interval)
			}
			if timeout != 2*time.Second {
				t.Errorf("Expected scrape timeout %d but got %d", 2*time.Second, timeout)
			}
			mtx.Lock()
			if !stopped[s.(*targetScraper).hash()] {
				t.Errorf("Scrape loop for %v not stopped yet", s.(*targetScraper))
			}
			mtx.Unlock()
		}
		return l
	}
	sp := &scrapePool{
		targets: map[uint64]*Target{},
		loops:   map[uint64]loop{},
		newLoop: newLoop,
	}

	// Reloading a scrape pool with a new scrape configuration must stop all scrape
	// loops and start new ones. A new loop must not be started before the preceeding
	// one terminated.

	for i := 0; i < numTargets; i++ {
		t := &Target{
			labels: model.LabelSet{
				model.AddressLabel: model.LabelValue(fmt.Sprintf("example.com:%d", i)),
			},
		}
		l := &testLoop{}
		l.stopFunc = func() {
			time.Sleep(time.Duration(i*20) * time.Millisecond)

			mtx.Lock()
			stopped[t.hash()] = true
			mtx.Unlock()
		}

		sp.targets[t.hash()] = t
		sp.loops[t.hash()] = l
	}
	done := make(chan struct{})

	beforeTargets := map[uint64]*Target{}
	for h, t := range sp.targets {
		beforeTargets[h] = t
	}

	reloadTime := time.Now()

	go func() {
		sp.reload(reloadCfg)
		close(done)
	}()

	select {
	case <-time.After(5 * time.Second):
		t.Fatalf("scrapeLoop.reload() did not return as expected")
	case <-done:
		// This should have taken at least as long as the last target slept.
		if time.Since(reloadTime) < time.Duration(numTargets*20)*time.Millisecond {
			t.Fatalf("scrapeLoop.stop() exited before all targets stopped")
		}
	}

	mtx.Lock()
	if len(stopped) != numTargets {
		t.Fatalf("Expected 20 stopped loops, got %d", len(stopped))
	}
	mtx.Unlock()

	if !reflect.DeepEqual(sp.targets, beforeTargets) {
		t.Fatalf("Reloading affected target states unexpectedly")
	}
	if len(sp.loops) != numTargets {
		t.Fatalf("Expected %d loops after reload but got %d", numTargets, len(sp.loops))
	}
}

// references a receiver not in the given map.
func checkReceiver(r *Route, receivers map[string]struct{}) error {
	if _, ok := receivers[r.Receiver]; !ok {
		return fmt.Errorf("Undefined receiver %q used in route", r.Receiver)
	}
	for _, sr := range r.Routes {
		if err := checkReceiver(sr, receivers); err != nil {
			return err
		}
	}
	return nil
}

// DefaultGlobalConfig provides global default values.
var DefaultGlobalConfig = GlobalConfig{
	ResolveTimeout: model.Duration(5 * time.Minute),

	PagerdutyURL:    "https://events.pagerduty.com/generic/2010-04-15/create_event.json",
	HipchatURL:      "https://api.hipchat.com/",
	OpsGenieAPIHost: "https://api.opsgenie.com/",
}

// GlobalConfig defines configuration parameters that are valid globally
// unless overwritten.
type GlobalConfig struct {
	// ResolveTimeout is the time after which an alert is declared resolved
	// if it has not been updated.
	ResolveTimeout model.Duration `yaml:"resolve_timeout"`

	SMTPFrom         string `yaml:"smtp_from"`
	SMTPSmarthost    string `yaml:"smtp_smarthost"`

func testFileSD(t *testing.T, ext string) {
	// As interval refreshing is more of a fallback, we only want to test
	// whether file watches work as expected.
	var conf config.FileSDConfig
	conf.Files = []string{"fixtures/_*" + ext}
	conf.RefreshInterval = model.Duration(1 * time.Hour)

	var (
		fsd         = NewDiscovery(&conf)
		ch          = make(chan []*config.TargetGroup)
		ctx, cancel = context.WithCancel(context.Background())
	)
	go fsd.Run(ctx, ch)

	select {
	case <-time.After(25 * time.Millisecond):
		// Expected.
	case tgs := <-ch:
		t.Fatalf("Unexpected target groups in file discovery: %s", tgs)
	}

	newf, err := os.Create("fixtures/_test" + ext)
	if err != nil {
		t.Fatal(err)
	}
	defer newf.Close()

	f, err := os.Open("fixtures/target_groups" + ext)
	if err != nil {
		t.Fatal(err)
	}
	defer f.Close()

	_, err = io.Copy(newf, f)
	if err != nil {
		t.Fatal(err)
	}
	newf.Close()

	timeout := time.After(15 * time.Second)
	// The files contain two target groups.
retry:
	for {
		select {
		case <-timeout:
			t.Fatalf("Expected new target group but got none")
		case tgs := <-ch:
			if len(tgs) != 2 {
				continue retry // Potentially a partial write, just retry.
			}
			tg := tgs[0]

			if _, ok := tg.Labels["foo"]; !ok {
				t.Fatalf("Label not parsed")
			}
			if tg.String() != fmt.Sprintf("fixtures/_test%s:0", ext) {
				t.Fatalf("Unexpected target group %s", tg)
			}

			tg = tgs[1]
			if tg.String() != fmt.Sprintf("fixtures/_test%s:1", ext) {
				t.Fatalf("Unexpected target groups %s", tg)
			}
			break retry
		}
	}

	// Based on unknown circumstances, sometimes fsnotify will trigger more events in
	// some runs (which might be empty, chains of different operations etc.).
	// We have to drain those (as the target manager would) to avoid deadlocking and must
	// not try to make sense of it all...
	drained := make(chan struct{})
	go func() {
	Loop:
		for {
			select {
			case tgs := <-ch:
				// Below we will change the file to a bad syntax. Previously extracted target
				// groups must not be deleted via sending an empty target group.
				if len(tgs[0].Targets) == 0 {
					t.Errorf("Unexpected empty target groups received: %s", tgs)
				}
			case <-time.After(500 * time.Millisecond):
				break Loop
			}
		}
		close(drained)
	}()

	newf, err = os.Create("fixtures/_test.new")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove(newf.Name())

	if _, err := newf.Write([]byte("]gibberish\n][")); err != nil {
		t.Fatal(err)
	}
	newf.Close()

//.........这里部分代码省略.........