// Copyright 2016 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// TODO(jba): test that OnError is getting called appropriately.

package logging_test

import (
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"log"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	cinternal "cloud.google.com/go/internal"
	"cloud.google.com/go/internal/testutil"
	"cloud.google.com/go/internal/uid"
	"cloud.google.com/go/logging"
	ltesting "cloud.google.com/go/logging/internal/testing"
	"cloud.google.com/go/logging/logadmin"
	gax "github.com/googleapis/gax-go/v2"
	"golang.org/x/oauth2"
	"google.golang.org/api/iterator"
	"google.golang.org/api/option"
	mrpb "google.golang.org/genproto/googleapis/api/monitoredres"
	logpb "google.golang.org/genproto/googleapis/logging/v2"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

const testLogIDPrefix = "GO-LOGGING-CLIENT/TEST-LOG"

var (
	client        *logging.Client
	aclient       *logadmin.Client
	testProjectID string
	testLogID     string
	testFilter    string
	errorc        chan error
	ctx           context.Context

	// Adjust the fields of a FullEntry received from the production service
	// before comparing it with the expected result. We can't correctly
	// compare certain fields, like times or server-generated IDs.
	clean func(*logging.Entry)

	// Create a new client with the given project ID.
	newClients func(ctx context.Context, projectID string) (*logging.Client, *logadmin.Client)

	uids = uid.NewSpace(testLogIDPrefix, nil)

	// If true, this test is using the production service, not a fake.
	integrationTest bool
)

func testNow() time.Time {
	return time.Unix(1000, 0)
}

func TestMain(m *testing.M) {
	flag.Parse() // needed for testing.Short()
	ctx = context.Background()
	testProjectID = testutil.ProjID()
	errorc = make(chan error, 100)
	if testProjectID == "" || testing.Short() {
		integrationTest = false
		if testProjectID != "" {
			log.Print("Integration tests skipped in short mode (using fake instead)")
		}
		testProjectID = ltesting.ValidProjectID
		clean = func(e *logging.Entry) {
			// Remove the insert ID for consistency with the integration test.
			e.InsertID = ""
		}

		addr, err := ltesting.NewServer()
		if err != nil {
			log.Fatalf("creating fake server: %v", err)
		}
		logging.SetNow(testNow)

		newClients = func(ctx context.Context, parent string) (*logging.Client, *logadmin.Client) {
			conn, err := grpc.Dial(addr, grpc.WithInsecure())
			if err != nil {
				log.Fatalf("dialing %q: %v", addr, err)
			}
			c, err := logging.NewClient(ctx, parent, option.WithGRPCConn(conn))
			if err != nil {
				log.Fatalf("creating client for fake at %q: %v", addr, err)
			}
			ac, err := logadmin.NewClient(ctx, parent, option.WithGRPCConn(conn))
			if err != nil {
				log.Fatalf("creating client for fake at %q: %v", addr, err)
			}
			return c, ac
		}

	} else {
		integrationTest = true
		clean = func(e *logging.Entry) {
			// We cannot compare timestamps, so set them to the test time.
			// Also, remove the insert ID added by the service.
			e.Timestamp = testNow().UTC()
			e.InsertID = ""
		}
		ts := testutil.TokenSource(ctx, logging.AdminScope)
		if ts == nil {
			log.Fatal("The project key must be set. See CONTRIBUTING.md for details")
		}
		log.Printf("running integration tests with project %s", testProjectID)
		newClients = func(ctx context.Context, parent string) (*logging.Client, *logadmin.Client) {
			c, err := logging.NewClient(ctx, parent, option.WithTokenSource(ts))
			if err != nil {
				log.Fatalf("creating prod client: %v", err)
			}
			ac, err := logadmin.NewClient(ctx, parent, option.WithTokenSource(ts))
			if err != nil {
				log.Fatalf("creating prod client: %v", err)
			}
			return c, ac
		}

	}
	client, aclient = newClients(ctx, testProjectID)
	client.OnError = func(e error) { errorc <- e }

	exit := m.Run()
	os.Exit(exit)
}

func initLogs() {
	testLogID = uids.New()
	hourAgo := time.Now().Add(-1 * time.Hour).UTC()
	testFilter = fmt.Sprintf(`logName = "projects/%s/logs/%s" AND
timestamp >= "%s"`,
		testProjectID, strings.Replace(testLogID, "/", "%2F", -1), hourAgo.Format(time.RFC3339))
}

func TestLogSync(t *testing.T) {
	initLogs() // Generate new testLogID
	ctx := context.Background()
	lg := client.Logger(testLogID)
	err := lg.LogSync(ctx, logging.Entry{Payload: "hello"})
	if err != nil {
		t.Fatal(err)
	}
	err = lg.LogSync(ctx, logging.Entry{Payload: "goodbye"})
	if err != nil {
		t.Fatal(err)
	}
	// Allow overriding the MonitoredResource.
	err = lg.LogSync(ctx, logging.Entry{Payload: "mr", Resource: &mrpb.MonitoredResource{Type: "global"}})
	if err != nil {
		t.Fatal(err)
	}

	want := []*logging.Entry{
		entryForTesting("hello"),
		entryForTesting("goodbye"),
		entryForTesting("mr"),
	}
	var got []*logging.Entry
	ok := waitFor(func() bool {
		got, err = allTestLogEntries(ctx)
		if err != nil {
			t.Log("fetching log entries: ", err)
			return false
		}
		return len(got) == len(want)
	})
	if !ok {
		t.Fatalf("timed out; got: %d, want: %d\n", len(got), len(want))
	}
	if msg, ok := compareEntries(got, want); !ok {
		t.Error(msg)
	}
}

func TestLogAndEntries(t *testing.T) {
	initLogs() // Generate new testLogID
	ctx := context.Background()
	payloads := []string{"p1", "p2", "p3", "p4", "p5"}
	lg := client.Logger(testLogID)
	for _, p := range payloads {
		// Use the insert ID to guarantee iteration order.
		lg.Log(logging.Entry{Payload: p, InsertID: p})
	}
	if err := lg.Flush(); err != nil {
		t.Fatal(err)
	}
	var want []*logging.Entry
	for _, p := range payloads {
		want = append(want, entryForTesting(p))
	}
	var got []*logging.Entry
	ok := waitFor(func() bool {
		var err error
		got, err = allTestLogEntries(ctx)
		if err != nil {
			t.Log("fetching log entries: ", err)
			return false
		}
		return len(got) == len(want)
	})
	if !ok {
		t.Fatalf("timed out; got: %d, want: %d\n", len(got), len(want))
	}
	if msg, ok := compareEntries(got, want); !ok {
		t.Error(msg)
	}
}

func TestContextFunc(t *testing.T) {
	initLogs()
	var contextFuncCalls, cleanupCalls int32 //atomic

	lg := client.Logger(testLogID, logging.ContextFunc(func() (context.Context, func()) {
		atomic.AddInt32(&contextFuncCalls, 1)
		return context.Background(), func() { atomic.AddInt32(&cleanupCalls, 1) }
	}))
	lg.Log(logging.Entry{Payload: "p"})
	if err := lg.Flush(); err != nil {
		t.Fatal(err)
	}
	got1 := atomic.LoadInt32(&contextFuncCalls)
	got2 := atomic.LoadInt32(&cleanupCalls)
	if got1 != 1 || got1 != got2 {
		t.Errorf("got %d calls to context func, %d calls to cleanup func; want 1, 1", got1, got2)
	}
}

func TestToLogEntry(t *testing.T) {
	u := &url.URL{Scheme: "http"}
	tests := []struct {
		name      string
		in        logging.Entry
		want      logpb.LogEntry
		wantError error
	}{
		{
			name: "BlankLogEntry",
			in:   logging.Entry{},
			want: logpb.LogEntry{},
		}, {
			name: "Already set Trace",
			in:   logging.Entry{Trace: "t1"},
			want: logpb.LogEntry{Trace: "t1"},
		}, {
			name: "No X-Trace-Context header",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{URL: u, Header: http.Header{"foo": {"bar"}}},
				},
			},
			want: logpb.LogEntry{},
		}, {
			name: "X-Trace-Context header with all fields",
			in: logging.Entry{
				TraceSampled: false,
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"105445aa7843bc8bf206b120001000/000000000000004a;o=1"}},
					},
				},
			},
			want: logpb.LogEntry{
				Trace:        "projects/P/traces/105445aa7843bc8bf206b120001000",
				SpanId:       "000000000000004a",
				TraceSampled: true,
			},
		}, {
			name: "X-Trace-Context header with all fields; TraceSampled explicitly set",
			in: logging.Entry{
				TraceSampled: true,
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"105445aa7843bc8bf206b120001000/000000000000004a;o=0"}},
					},
				},
			},
			want: logpb.LogEntry{
				Trace:        "projects/P/traces/105445aa7843bc8bf206b120001000",
				SpanId:       "000000000000004a",
				TraceSampled: true,
			},
		}, {
			name: "X-Trace-Context header with all fields; TraceSampled from Header",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"105445aa7843bc8bf206b120001000/000000000000004a;o=1"}},
					},
				},
			},
			want: logpb.LogEntry{
				Trace:        "projects/P/traces/105445aa7843bc8bf206b120001000",
				SpanId:       "000000000000004a",
				TraceSampled: true,
			},
		}, {
			name: "X-Trace-Context header with blank trace",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"/0;o=1"}},
					},
				},
			},
			want: logpb.LogEntry{
				TraceSampled: true,
			},
		}, {
			name: "X-Trace-Context header with blank span",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"105445aa7843bc8bf206b120001000/;o=0"}},
					},
				},
			},
			want: logpb.LogEntry{
				Trace: "projects/P/traces/105445aa7843bc8bf206b120001000",
			},
		}, {
			name: "X-Trace-Context header with missing traceSampled aka ?o=*",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"105445aa7843bc8bf206b120001000/0"}},
					},
				},
			},
			want: logpb.LogEntry{
				Trace: "projects/P/traces/105445aa7843bc8bf206b120001000",
			},
		}, {
			name: "X-Trace-Context header with all blank fields",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {""}},
					},
				},
			},
			want: logpb.LogEntry{},
		}, {
			name: "Invalid X-Trace-Context header but already set TraceID",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					Request: &http.Request{
						URL:    u,
						Header: http.Header{"X-Cloud-Trace-Context": {"t3"}},
					},
				},
				Trace: "t4",
			},
			want: logpb.LogEntry{
				Trace: "t4",
			},
		}, {
			name: "Already set TraceID and SpanID",
			in:   logging.Entry{Trace: "t1", SpanID: "007"},
			want: logpb.LogEntry{
				Trace:  "t1",
				SpanId: "007",
			},
		}, {
			name: "Empty request produces an error",
			in: logging.Entry{
				HTTPRequest: &logging.HTTPRequest{
					RequestSize: 128,
				},
			},
			wantError: errors.New("logging: HTTPRequest must have a non-nil Request"),
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			e, err := logging.ToLogEntry(test.in, "projects/P")
			if err != nil && test.wantError == nil {
				t.Fatalf("Unexpected error: %+v: %v", test.in, err)
			}
			if err == nil && test.wantError != nil {
				t.Fatalf("Error is expected: %+v: %v", test.in, test.wantError)
			}
			if test.wantError != nil {
				return
			}
			if got := e.Trace; got != test.want.Trace {
				t.Errorf("TraceId: %+v: got %q, want %q", test.in, got, test.want.Trace)
			}
			if got := e.SpanId; got != test.want.SpanId {
				t.Errorf("SpanId: %+v: got %q, want %q", test.in, got, test.want.SpanId)
			}
			if got := e.TraceSampled; got != test.want.TraceSampled {
				t.Errorf("TraceSampled: %+v: got %t, want %t", test.in, got, test.want.TraceSampled)
			}
		})
	}
}

// compareEntries compares most fields list of Entries against expected. compareEntries does not compare:
//   - HTTPRequest
//   - Operation
//   - Resource
//   - SourceLocation
func compareEntries(got, want []*logging.Entry) (string, bool) {
	if len(got) != len(want) {
		return fmt.Sprintf("got %d entries, want %d", len(got), len(want)), false
	}
	for i := range got {
		if !compareEntry(got[i], want[i]) {
			return fmt.Sprintf("#%d:\ngot  %+v\nwant %+v", i, got[i], want[i]), false
		}
	}
	return "", true
}

func compareEntry(got, want *logging.Entry) bool {
	if got.Timestamp.Unix() != want.Timestamp.Unix() {
		return false
	}

	if got.Severity != want.Severity {
		return false
	}

	if !ltesting.PayloadEqual(got.Payload, want.Payload) {
		return false
	}
	if !testutil.Equal(got.Labels, want.Labels) {
		return false
	}

	if got.InsertID != want.InsertID {
		return false
	}

	if got.LogName != want.LogName {
		return false
	}

	return true
}

func entryForTesting(payload interface{}) *logging.Entry {
	return &logging.Entry{
		Timestamp: testNow().UTC(),
		Payload:   payload,
		LogName:   "projects/" + testProjectID + "/logs/" + testLogID,
		Resource:  &mrpb.MonitoredResource{Type: "global", Labels: map[string]string{"project_id": testProjectID}},
	}
}

// allTestLogEntries should be called sparingly. It takes ~10s to get logs, even with indexed filters.
func allTestLogEntries(ctx context.Context) ([]*logging.Entry, error) {
	return allEntries(ctx, aclient, testFilter)
}

func allEntries(ctx context.Context, aclient *logadmin.Client, filter string) ([]*logging.Entry, error) {
	var es []*logging.Entry
	it := aclient.Entries(ctx, logadmin.Filter(filter))
	for {
		e, err := cleanNext(it)
		switch err {
		case nil:
			es = append(es, e)
		case iterator.Done:
			return es, nil
		default:
			return nil, err
		}
	}
}

func cleanNext(it *logadmin.EntryIterator) (*logging.Entry, error) {
	e, err := it.Next()
	if err != nil {
		return nil, err
	}
	clean(e)
	return e, nil
}

func TestStandardLogger(t *testing.T) {
	initLogs() // Generate new testLogID
	ctx := context.Background()
	lg := client.Logger(testLogID)
	slg := lg.StandardLogger(logging.Info)

	if slg != lg.StandardLogger(logging.Info) {
		t.Error("There should be only one standard logger at each severity.")
	}
	if slg == lg.StandardLogger(logging.Debug) {
		t.Error("There should be a different standard logger for each severity.")
	}

	slg.Print("info")
	if err := lg.Flush(); err != nil {
		t.Fatal(err)
	}
	var got []*logging.Entry
	ok := waitFor(func() bool {
		var err error
		got, err = allTestLogEntries(ctx)
		if err != nil {
			t.Log("fetching log entries: ", err)
			return false
		}
		return len(got) == 1
	})
	if !ok {
		t.Fatalf("timed out; got: %d, want: %d\n", len(got), 1)
	}
	if len(got) != 1 {
		t.Fatalf("expected non-nil request with one entry; got:\n%+v", got)
	}
	if got, want := got[0].Payload.(string), "info\n"; got != want {
		t.Errorf("payload: got %q, want %q", got, want)
	}
	if got, want := logging.Severity(got[0].Severity), logging.Info; got != want {
		t.Errorf("severity: got %s, want %s", got, want)
	}
}

func TestSeverity(t *testing.T) {
	if got, want := logging.Info.String(), "Info"; got != want {
		t.Errorf("got %q, want %q", got, want)
	}
	if got, want := logging.Severity(-99).String(), "-99"; got != want {
		t.Errorf("got %q, want %q", got, want)
	}
}

func TestParseSeverity(t *testing.T) {
	for _, test := range []struct {
		in   string
		want logging.Severity
	}{
		{"", logging.Default},
		{"whatever", logging.Default},
		{"Default", logging.Default},
		{"ERROR", logging.Error},
		{"Error", logging.Error},
		{"error", logging.Error},
	} {
		got := logging.ParseSeverity(test.in)
		if got != test.want {
			t.Errorf("%q: got %s, want %s\n", test.in, got, test.want)
		}
	}
}

func TestErrors(t *testing.T) {
	initLogs() // Generate new testLogID
	// Drain errors already seen.
loop:
	for {
		select {
		case <-errorc:
		default:
			break loop
		}
	}
	// Try to log something that can't be JSON-marshalled.
	lg := client.Logger(testLogID)
	lg.Log(logging.Entry{Payload: func() {}})
	// Expect an error from Flush.
	err := lg.Flush()
	if err == nil {
		t.Fatal("expected error, got nil")
	}
}

type badTokenSource struct{}

func (badTokenSource) Token() (*oauth2.Token, error) {
	return &oauth2.Token{}, nil
}

func TestPing(t *testing.T) {
	// Ping twice, in case the service's InsertID logic messes with the error code.
	ctx := context.Background()
	// The global client should be valid.
	if err := client.Ping(ctx); err != nil {
		t.Errorf("project %s: got %v, expected nil", testProjectID, err)
	}
	if err := client.Ping(ctx); err != nil {
		t.Errorf("project %s, #2: got %v, expected nil", testProjectID, err)
	}
	// nonexistent project
	c, a := newClients(ctx, testProjectID+"-BAD")
	defer c.Close()
	defer a.Close()
	if err := c.Ping(ctx); err == nil {
		t.Errorf("nonexistent project: want error pinging logging api, got nil")
	}
	if err := c.Ping(ctx); err == nil {
		t.Errorf("nonexistent project, #2: want error pinging logging api, got nil")
	}

	// Bad creds. We cannot test this with the fake, since it doesn't do auth.
	if integrationTest {
		c, err := logging.NewClient(ctx, testProjectID, option.WithTokenSource(badTokenSource{}))
		if err != nil {
			t.Fatal(err)
		}
		if err := c.Ping(ctx); err == nil {
			t.Errorf("bad creds: want error pinging logging api, got nil")
		}
		if err := c.Ping(ctx); err == nil {
			t.Errorf("bad creds, #2: want error pinging logging api, got nil")
		}
		if err := c.Close(); err != nil {
			t.Fatalf("error closing client: %v", err)
		}
	}
}

func TestDeleteLog(t *testing.T) {
	ctx := context.Background()
	initLogs()
	c, a := newClients(ctx, testProjectID)
	defer c.Close()
	defer a.Close()
	lg := c.Logger(testLogID)

	if err := lg.LogSync(ctx, logging.Entry{Payload: "hello"}); err != nil {
		t.Fatal(err)
	}

	if err := aclient.DeleteLog(ctx, testLogID); err != nil {
		// Ignore NotFound. Sometimes, amazingly, DeleteLog cannot find
		// a log that is returned by Logs.
		if status.Code(err) != codes.NotFound {
			t.Fatalf("deleting %q: %v", testLogID, err)
		}
	} else {
		t.Logf("deleted log_id: %q", testLogID)
	}
}

func TestNonProjectParent(t *testing.T) {
	ctx := context.Background()
	initLogs()
	parent := "organizations/" + ltesting.ValidOrgID
	c, a := newClients(ctx, parent)
	defer c.Close()
	defer a.Close()
	lg := c.Logger(testLogID)
	err := lg.LogSync(ctx, logging.Entry{Payload: "hello"})
	if integrationTest {
		// We don't have permission to log to the organization.
		if got, want := status.Code(err), codes.PermissionDenied; got != want {
			t.Errorf("got code %s, want %s", got, want)
		}
		return
	}
	// Continue test against fake.
	if err != nil {
		t.Fatal(err)
	}
	want := []*logging.Entry{{
		Timestamp: testNow().UTC(),
		Payload:   "hello",
		LogName:   parent + "/logs/" + testLogID,
		Resource: &mrpb.MonitoredResource{
			Type:   "organization",
			Labels: map[string]string{"organization_id": ltesting.ValidOrgID},
		},
	}}
	var got []*logging.Entry
	ok := waitFor(func() bool {
		got, err = allEntries(ctx, a, fmt.Sprintf(`logName = "%s/logs/%s"`, parent,
			strings.Replace(testLogID, "/", "%2F", -1)))
		if err != nil {
			t.Log("fetching log entries: ", err)
			return false
		}
		return len(got) == len(want)
	})
	if !ok {
		t.Fatalf("timed out; got: %d, want: %d\n", len(got), len(want))
	}
	if msg, ok := compareEntries(got, want); !ok {
		t.Error(msg)
	}
}

// waitFor calls f repeatedly with exponential backoff, blocking until it returns true.
// It returns false after a while (if it times out).
func waitFor(f func() bool) bool {
	// TODO(shadams): Find a better way to deflake these tests.
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Minute)
	defer cancel()
	err := cinternal.Retry(ctx,
		gax.Backoff{Initial: time.Second, Multiplier: 2, Max: 30 * time.Second},
		func() (bool, error) { return f(), nil })
	return err == nil
}

// Interleave a lot of Log and Flush calls, to induce race conditions.
// Run this test with:
//   go test -run LogFlushRace -race -count 100
func TestLogFlushRace(t *testing.T) {
	initLogs() // Generate new testLogID
	lg := client.Logger(testLogID,
		logging.ConcurrentWriteLimit(5),  // up to 5 concurrent log writes
		logging.EntryCountThreshold(100)) // small bundle size to increase interleaving
	var wgf, wgl sync.WaitGroup
	donec := make(chan struct{})
	for i := 0; i < 10; i++ {
		wgl.Add(1)
		go func() {
			defer wgl.Done()
			for j := 0; j < 1e4; j++ {
				lg.Log(logging.Entry{Payload: "the payload"})
			}
		}()
	}
	for i := 0; i < 5; i++ {
		wgf.Add(1)
		go func() {
			defer wgf.Done()
			for {
				select {
				case <-donec:
					return
				case <-time.After(time.Duration(rand.Intn(5)) * time.Millisecond):
					if err := lg.Flush(); err != nil {
						t.Error(err)
					}
				}
			}
		}()
	}
	wgl.Wait()
	close(donec)
	wgf.Wait()
}

// Test the throughput of concurrent writers.
func BenchmarkConcurrentWrites(b *testing.B) {
	if !integrationTest {
		b.Skip("only makes sense when running against production service")
	}
	for n := 1; n <= 32; n *= 2 {
		b.Run(fmt.Sprint(n), func(b *testing.B) {
			b.StopTimer()
			lg := client.Logger(testLogID, logging.ConcurrentWriteLimit(n), logging.EntryCountThreshold(1000))
			const (
				nEntries = 1e5
				payload  = "the quick brown fox jumps over the lazy dog"
			)
			b.SetBytes(int64(nEntries * len(payload)))
			b.StartTimer()
			for i := 0; i < b.N; i++ {
				for j := 0; j < nEntries; j++ {
					lg.Log(logging.Entry{Payload: payload})
				}
				if err := lg.Flush(); err != nil {
					b.Fatal(err)
				}
			}
		})
	}
}

func TestSeverityUnmarshal(t *testing.T) {
	j := []byte(`{"logName": "test-log","severity": "ERROR","payload": "test"}`)
	var entry logging.Entry
	err := json.Unmarshal(j, &entry)
	if err != nil {
		t.Fatalf("en.Unmarshal: %v", err)
	}
	if entry.Severity != logging.Error {
		t.Fatalf("Severity: got %v, want %v", entry.Severity, logging.Error)
	}
}

func TestSeverityAsNumberUnmarshal(t *testing.T) {
	j := []byte(fmt.Sprintf(`{"logName": "test-log","severity": %d, "payload": "test"}`, logging.Info))
	var entry logging.Entry
	err := json.Unmarshal(j, &entry)
	if err != nil {
		t.Fatalf("en.Unmarshal: %v", err)
	}
	if entry.Severity != logging.Info {
		t.Fatalf("Severity: got %v, want %v", entry.Severity, logging.Info)
	}
}

func TestSeverityMarshalThenUnmarshal(t *testing.T) {
	entry := logging.Entry{Severity: logging.Warning, Payload: "test"}
	j, err := json.Marshal(entry)
	if err != nil {
		t.Fatalf("en.Marshal: %v", err)
	}

	var entryU logging.Entry

	err = json.Unmarshal(j, &entryU)
	if err != nil {
		t.Fatalf("en.Unmarshal: %v", err)
	}

	if entryU.Severity != logging.Warning {
		t.Fatalf("Severity: got %v, want %v", entryU.Severity, logging.Warning)
	}
}